Rotating Machinery

Isolated areas in Brazil are usually served by diesel based electricity supply. The diesel fuel is usually transported by river to these isolated communities. During dry, wet seasons and inundations the transport is very risky and not usually safe. As a result the communities have to manage without electricity. To guarantee access of these communities to reliable electricity supply, better strategies have to be implemented based on renewable energy sources available in the area. The hydrokinetic technology is among the promising technologies since it is relatively cheap, easy to manufacture, reliable and suitable for most of the Amazon areas. In this paper the authors propose a cheap hydrokinetic turbine system whose blades are easy to design, manufacture, and needs simple transmission systems. In this work CFD and RANS (Reynolds Average Navier Stokes) equations were used to characterize and develop a methodology for numerical simulation of a vertical axis hydrokinetic turbine. In t...

In this study, the Plücker coordinates representation is used to formulate the ruled surface and the molecular path for pumping speed performance evaluation of a molecular vacuum pump. The ruled surface represented by the Pliicker coordinates is used to develop a criterion for when gas molecules hit the pump surface wall. The criterion is applied to analyze the flow rate of a new developed vacuum pump in transition regimes by using the DSMC (Direct Simulation Monte Carlo) method. When a molecule flies in a neutral electrical field its path is a straight line. If the molecular path and the generators of a ruled surface are both represented by the Pliicker coordinates, the position of the molecular hit on the wall can be verified by the reciprocal condition of the lines. The Plücker coordinates representation is quite convenient in the DSMC method for this three-dimensional molecular flow simulation.

's Thesis : Loss Sources and Magnitudes Breakdown in an Axial Low Pressure Compressor Blade Row[BR]-Internship (linked to master's thesis) Auteur : Crutzen, Gilles Promoteur(s) : Hillewaert, Koen Faculté : Faculté des Sciences appliquées Diplôme : Master en ingénieur civil en aérospatiale, à finalité spécialisée en "aerospace engineering"

W pracy oszacowano efekty zastosowania w KSE (Krajowym Systemie Elektroenergetycznym) magazynów bateryjnych o pojemności 17 GWh, oraz oszacowano pojemność wymaganą dla likwidacji segmentu JWCD (Jednostek Wytwórczych Centralnie Dysponowanych) oraz wymaganą dla całkowitej likwidacji źródeł sterowalnych. The paper estimates the effects of using battery storage with a capacity of 17 GWh in the National Power System (KSE), and estimates the capacity required for the liquidation of the JWCD (Centrally Dispatched Generating Units) segment and the capacity required for the complete liquidation of controllable sources.

Based on experimental observations on a set of twenty 700 MW hydrogenerators, compiled from several technical reports issued over the last three decades and collected from the reprocessing of the vibration signals recorded during the last commissioning tests, this paper shows that the accurate determination of the journal bearings operating conditions may be a difficult task. It shows that the outsize bearing brackets of large hydrogenerators are subject to substantial dimensional changes caused by external agents, like the generator electromagnetic field and the bearing cooling water temperature. It also shows that the shaft eccentricity of a journal bearing of a healthy large hydrogenerator, operating in steady-state condition, may experience unpredictable, sudden, and significant changes without apparent reasons. Some of these phenomena are reproduced in ordinary commissioning tests or may be noticed even during normal operation, while others are rarely observed or are only detec...

Streszczenie angielskie: The numerical investigations of a flow in the model turbine are presented. The clocking phenomena in the two-stage turbine with low-aspect and highly loaded blade rows are studied. The quasi-unsteady simulations by means of the frozen rotor approach were conducted for several circumferential relative positions of stators. The optimum clocking position was predicted on the basis of the estimated turbine efficiency. The effects of clocking on wake interactions and blade loading variations are presented and ...

Streszczenie angielskie: The paper describes the experimental and numerical investigations of stator clocking effects on performance of a two-stage impulse turbine with low-aspect ratio airfoils. The data present the clocking effect that can be observed both for local flow patterns and external characteristics for the entire turbine in terms of efficiency. Finding an optimal relative circumferential position of stators in a multistage axial turbine has been the subject of extensive investigations in the last decade.

The PG45 DC motor is a drive system used on sediment detection boat. To achieve the desired stability and speed, it is necessary to apply a control system to the sediment detection boat drive system. Control systems need to be tuned to ensure that they function properly and are responsive to changes. In order to complement the previous research, further research was carried out focusing on determining the PID control parameters on the angular speed of the PG45 DC Motor using Simulink. The PG45 DC motor works based on the Arduino programming algorithm that has been designed so that it can rotate at a predetermined speed. This research modeled the sediment detection ship system on Simulink with a similarity rate of 94.09%. The results of this study indicate that the tuning method used, namely trial and error, produces good control on the sediment detection ship system model that has been assembled in Simulink with the value of Kp = 100; Ki = 5; Kd = 15 obtained the value of rise time = 0.2474 seconds and settling time = 0.4104 seconds and overshoot = 0.2175%%.

Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) program plays a key part in helping NASA maintain this important role. The NASA STI Program operates under the auspices of the Agency Chief Information Officer. It collects, organizes, provides for archiving, and disseminates NASA's STI. The NASA STI program provides access to the NASA Aeronautics and Space Database and its public interface, the NASA Technical Reports Server, thus providing one of the largest collections of aeronautical and space science STI in the world. Results are published in both non-NASA channels and by NASA in the NASA STI Report Series, which includes the following report types: The 2006 NASA Seal/Secondary Air System workshop covered the following topics: (i) Overview of NASA's new Exploration Initiative program aimed at exploring the Moon, Mars, and beyond; (ii) Overview of NASA's new fundamental aeronautics technology project; (iii) Overview of NASA Glenn Research Center's seal project aimed at developing advanced seals for NASA's turbomachinery, space, and reentry vehicle needs; (iv) Reviews of NASA prime contractor, vendor, and university advanced sealing concepts including tip clearance control, test results, experimental facilities, and numerical predictions; and (v) Reviews of material development programs relevant to advanced seals development. NASA's fundamental aeronautics project is developing advanced technologies for subsonic rotary and fixed-wing aircraft and supersonic and hypersonic aircraft. Turbine engine studies have shown that reducing high-pressure turbine (HPT) blade tip clearances will reduce fuel burn, lower emissions, retain exhaust gas temperature margin, and increase range for subsonic aircraft. General Electric presented an approach for a fast-acting thermal active clearance control system. NASA Glenn researchers presented efforts underway to develop new Active Clearance Control (ACC) kinematic systems, actuators, control methods, and sensors. Test results were shown for a new NASA Glenn active clearance control test rig used to evaluate a fast-acting ACC concept incorporating seals and control methods. Vibro-meter presented an overview of their microwave blade tip sensor development efforts. Microwave tip sensors show promise of operation in the extreme gas temperatures (>2000 °F) present in the HPT location. The workshop also covered several programs NASA is funding to develop technologies for the Exploration Initiative and advanced reusable space vehicle technologies. NASA plans on developing a Low Impact Docking System (LIDS) that would become the Agency's standard for docking and berthing for the Exploration Initiative. Seal technical challenges (including space environments, temperature variation, and seal-on-seal operation) as well as plans to develop the necessary "androgynous" seal technologies were reviewed. Future reentry and other hypersonic vehicles pose a variety of challenges including high temperature, resiliency at operating temperature to accommodate gap changes during operation, and durability to meet mission requirements. Researchers also reviewed seal technologies employed by the Apollo command module that serve as an excellent basis for seals for NASA's new Crew Exploration Vehicle (CEV).

The 2005 NASA Seal/Secondary Air System workshop covered the following topics: (i) Overview of NASA's new Exploration Initiative program aimed at exploring the Moon, Mars, and beyond; (ii) Overview of the NASA-sponsored Propulsion 21 project; (iii) Overview of NASA Glenn Research Center's seal project aimed at developing advanced seals for NASA's turbomachinery, space, and reentry vehicle needs; (iv) Reviews of NASA prime contractor, vendor, and university advanced sealing concepts including tip clearance control, test results, experimental facilities, and numerical predictions; and (v) Reviews of material development programs relevant to advanced seals development. NASA's Propulsion 21 project is developing advanced turbine engine technologies aimed at reducing fuel burn, emissions, and noise through a consortium of Ohio organizations. Development of advanced clearance control techniques is a subelement of the Propulsion 21 project. Turbine engine studies have shown that reducing high-pressure turbine (HPT) blade tip clearances will reduce fuel burn, lower emissions, retain exhaust gas temperature margin, and increase range. GE presented an approach for a fast-acting thermal active clearance control (ACC) system. NASA Glenn researchers presented efforts underway to develop new ACC kinematic systems, actuators, control methods, and sensors. Test results were shown for a new NASA Glenn active clearance control test rig used to evaluate a fast-acting ACC concept incorporating seals and control methods. Radatech presented an overview of their microwave blade tip sensor development efforts. Microwave tip sensors show promise of operation in the extreme gas temperatures (>2000 °F) present in the HPT location. The workshop also covered several programs NASA is funding to develop technologies for the Exploration Initiative and advanced reusable space vehicle technologies. NASA plans on developing an advanced docking and berthing system that would permit any vehicle to dock to any on-orbit station or vehicle. Seal technical challenges (including space environments, temperature variation, and seal-on-seal operation) as well as plans to develop the necessary "androgynous" seal technologies were reviewed. Future reentry and other hypersonic vehicles pose a variety of challenges including high-temperature, resiliency at operating temperature to accommodate gap changes during operation, and durability to meet mission requirements. Researchers also reviewed tests completed for the shuttle main landing-gear door seals.

FSD = Full Scale Demonstration Flight demonstration of multiple day, unrefueled flight using a hydrogen/air fuel cell power system. Demonstrate through integrated ground tests, a constant volume combustor in an engine system, & a UAV/small transport aircraft fuel cell-based power system. Flight demonstration of a UAV/small transport aircraft fuel cell-based power system with lower operational costs & improved performance. Perform a ground demonstration of an integrated alternative-fueled engine-power system for a small transport aircraft. Vehicle Systems Strategic Focus -Supporting Projects New Aircraft Energy Sources and Management Discover new energy sources and intelligent energy management techniques directed towards zero emissions and enable new vehicle concepts for public mobility and new science missions. LEAP Flight demonstration of a UAV fuel cell-based power system providing extremely long duration flights. Demonstrate through integrated ground tests, a constant volume combustor in an engine system, and a UAV/small transport aircraft fuel cell-based power generation system.

Wheel aerodynamics of passenger cars has recently been under close investigation due to its influence on the aerodynamic forces on the vehicle. In modern wind-tunnels the wheel rotation can be resembled close to reality, while, in their CFD development process, car manufactures rely on simplified models for considering rotating wheels. In this paper, model-scale generic and production wheels are investigated experimentally, in respect of the influence of geometry, camber and a brake disc. The data is used to assess the accuracy of CFD simulations using open-source software and their applicability in a manufacturer's CFD process.

Approximately 25% of the aerodynamic drag of passenger vehicles is contributed by the wheels. Small features in the tire geometry and the contact area between tire and ground can induce flow separation. Thus, the wheel wake features complex flow phenomena. To understand the appearing flow phenomena, a correct geometry representation of the rotating tire in CFD is essential. The model has to cover the rotating tread, the deformation due to weight and centrifugal forces. Realistic detailed and/or deformed tires are investigated with OpenFOAM® employing a hybrid approach to study the influence of geometrical features on the flow field and coefficients.

Approximately 25% of the aerodynamic drag of passenger vehicles is contributed by the wheels. Small features in the tire geometry and the contact area between tire and ground can induce flow separation. Thus, the wheel wake features complex flow phenomena. To understand the appearing flow phenomena, a correct geometry representation of the rotating tire in CFD is essential. The model has to cover the rotating tread, the deformation due to weight and centrifugal forces. Realistic detailed and/or deformed tires are investigated with OpenFOAM® employing a hybrid approach to study the influence of geometrical features on the flow field and coefficients.

Naval architecture and ocean engineering deal with design and operation of a large variety of structures for use at sea. Striving for cost effective and safe designs has resulted in development of sophisticated methods for predicting the behaviour of these structures. The core disciplines have been oceanography, hydrodynamics, dynamics, structural mechanics, and material science, but recently we have also seen an increasing use of cybernetics and information technology. Applied mathematics is the common tool we have when applying the basic disciplines on our practical problems. This special issue attracted a large interest, mainly from academic institutions dealing with marine, civil and mechanical engineering, but also applied mathematics. More than 50 papers were submitted, and 22 of these were accepted for publication. The largest group of accepted papers deals with marine hydrodynamics. Various aspects of ocean wave theories are discussed in five papers. Key words to describe the content are shallow water, tsunamis, modulation instabilities of wave systems, numerical wave tank, and use of particle finite element models. Two papers deal with sloshing in tanks and discussions of rigid body motions of floating bodies are found in two papers. Hydroelasticity means that dynamic simulations require an integrated calculation of elastic deformations and hydrodynamic forces. Three papers fall into this category. Dynamic response of marine structures is another important discipline in marine technology, and six papers are found in this category. Collision between ships and other types of elastic structures is analysed in two papers. Flexible risers and umbilicals represent

An experimental investigation has been conducted to characterize the influence of leading edge roughness and Reynolds number on compressor cascade profile loss. Tests have been conducted in a low-speed linear compressor cascade at Reynolds numbers between 210,000 and 640,000. Blade loading and loss have been measured with pressure taps and pneumatic probes. In addition, a two-component laser-doppler velocimeter (LDV) has been used to measure the boundary layer velocity profiles and turbulence levels at various chordwise locations near the blade suction surface. The “smooth” blade has a centerline-averaged roughness (Ra) of 0.62 μm. The “rough” blade is roughened by covering the leading edge of the “smooth” blade, including 2% of the pressure side and 2% of the suction side, with a 100 μm-thick tape with a roughness Ra of 4.97 μm. At Reynolds numbers ranging from 210,000 to 380,000, the leading edge roughness decreases loss slightly. At Reynolds number of 210,000, the leading edge ro...

An experimental investigation has been conducted to characterize the influence of Reynolds number and surface roughness magnitude and location on compressor cascade performance. Flow field surveys have been conducted in a low-speed, linear compressor cascade. Pressure, velocity, and loss have been measured via a five-hole probe, pitot probe, and pressure taps on the blades. Four different roughness magnitudes, Ra values of 0.38 μm (polished), 1.70 μm (baseline), 2.03 μm (rough 1), and 2.89 μm (rough 2), have been tested. Furthermore, various roughness locations have been examined. In addition to the as manufactured (baseline) and entirely rough blade cases, blades with roughness covering the leading edge, pressure side, and 5%, 20%, 35%, 50%, and 100% of suction side from the leading edge have been studied. All of the tests have been carried out for Reynolds numbers ranging from 300,000 to 640,000. For Reynolds numbers under 500,000, the tested roughnesses do not significantly degra...

A unique experimental investigation of cavitation signatures in an automotive torque converter under stall conditions is reported. A quantitative criterion is proposed for predicting early and advanced cavitation in terms of suitable nondimensional pump speeds. The dimensionless pump speed that marks early cavitation is obtained by relating this parameter to the appearance of charge-pressure–dependent pressure fluctuations in the differential pressure transducer readings. The differential pressure transducers were mounted at well-defined locations in the pump passage of a torque converter. The data were transmitted by a wireless telemetry system mounted on the pump housing. Data were received and processed by a ground-based data acquisition system. Automatic transmission fluid exhibited cavitation for charge pressures of 70–130 psi and pump speeds of 1000– 2250 rpm. Advanced cavitation was marked by operating conditions that exhibited a 2% or more torque degradation from the convert...

This paper presents the application of optimization method developed by Hashimoto to design oil lubricated thrust bearings for 2.5 inch form factor hard disk drives (HDD). The designing involves optimization of groove geometry and dimensions. Calculations are carried out to maximize the dynamic stiffness of the thrust bearing spindle motor. Static and dynamic characteristics of the modeled thrust bearing are calculated using the divergence formulation method. Results show that, by using the proposed optimization method, dynamic stiffness values can be well improved with the bearing geometries not being fixed to conventional grooves.

In this research, numerical optimization of the rear part of a gas turbine, consisting of a single-stage axial turbine, is carried out. Automated aerodynamic shape optimization is performed by coupling a CFD flow simulation code with the genetic algorithm. An effective multipoint optimization method to improve efficiency and/or pressure ratio of the axial turbine is performed. Some variations of optimization parameters such as lean and sweep angels of stator and rotor blades are accomplished. Furthermore, during the optimization process, three-dimensional and turbulent flow field is numerically investigated using a compressible Navier-Stokes solver. The gas turbine experimental investigations are used for choosing optimization points, specifying the boundary conditions and validation of the simulations. Two operating speeds of the gas turbine are selected for the optimization. Using verified numerical simulation models and the genetic algorithm, the effects of stator and rotor lean and sweep angles on the turbine performance are studied. The present optimization method successfully obtains a result that improves 1.31 and 1.17 % in the turbine stage total-to-total efficiency in its design and off-design speeds, respectively. The modified turbine mass parameter at choke condition increases 2.40 %.

In this research, numerical optimization of the rear part of a gas turbine, consisting of a single stage axial turbine is carried out. Automated aerodynamic shape optimization is performed by coupling a CFD flow simulation code with the Genetic Algorithm. An effective multi-point optimization method to improve efficiency and/or pressure ratio of the axial turbine is performed. Some variations of optimization parameters such as lean and sweep angels of stator and rotor blades are accomplished. Furthermore, during the optimization process, three-dimensional and turbulent flow field is numerically investigated using a compressible Navier-Stokes solver. The gas turbine experimental investigations are used for choosing optimization points, specifying the boundary conditions and validation of the simulations. Two operating speeds of the gas turbine are selected for the optimization. Using verified numerical simulation models and the genetic algorithm, the effects of stator and rotor lean ...

This paper presents an experimental investigation of turbulent flow inside square-sectioned channels connected with a square-ended bend using particle image velocimetry (PIV). Aluminium porous foam blocks of aspect ratio of 1.5 with 0.93 porosity and pore density per cm of 2, are attached to two opposite walls of the straight section normal to the turn axis, in a staggered manner. The spacing ratio of the blocks (S /D) is 1; whereas the height ratio (h/D) is 0.6. Water is used as the working fluid at Reynolds number of 36,000. The duct is either stationary or rotates orthogonally about an axis normal to that of the turn at a rotation number of 0.32. Results show the serpentine manner of the flow in the upstream and downstream channels due to the presence of the porous blocks. While in the straight sections there is no flow separation downstream of each block, turbulence levels are raised by the blocks' presence. Within the bend, in contrast to the case with a smooth upstream section, a single vortex dominates the flow. For the first time, the effects of orthogonal rotation are also highlighted. While rotation does not change the overall flow character, it does force more fluid through the blocks on the duct trailing (pressure) side.

This paper presents an experimental investigation of turbulent flow inside squaresectioned channels connected with a square-ended bend using particle image velocimetry (PIV). Aluminium porous foam blocks of aspect ratio of 1.5 with 0.93 porosity and pore density per cm of 2, are attached to two opposite walls of the straight section normal to the turn axis, in a staggered manner. The spacing ratio of the blocks (S/D) is 1; whereas the height ratio (h/D) is 0.6. Water is used as the working fluid at Reynolds number of 36,000. The duct is either stationary or rotates orthogonally about an axis normal to that of the turn at a rotation number of 0.32. Results show the serpentine manner of the flow in the upstream and downstream channels due to the presence of the porous blocks. While in the straight sections there is no flow separation downstream of each block, turbulence levels are raised by the blocks’ presence. Within the bend, in contrast to the case with a smooth upstream section, ...

Due to increased demands for improved fuel economy of passenger cars, low-end and part-load performance is of key importance for the design of automotive turbocharger turbines. In an automotive drive cycle, a turbine which can extract more energy at high pressure ratios and lower rotational speeds is desirable. In the literature it is typically found that radial turbines provide peak efficiency at speed ratios of 0.7, but at high pressure ratios and low rotational speeds the blade speed ratio will be low and the rotor will experience high values of positive incidence at the inlet. Based on fundamental considerations, it is shown that mixed flow turbines offer substantial advantages for such applications. Moreover, to prove these considerations an experimental assessment of mixed flow turbine efficiency and optimal blade speed ratio is presented. This has been achieved using a new semi-unsteady measurement approach. Finally, evidence of the benefits of mixed flow turbine behaviour in...

For numerical simulations of cavitating flows, many physical models are currently used. One approach is the void fraction transport equation-based model including source terms for vaporization and condensation processes. Various source terms have been proposed by different researchers. However, they have been tested only in different flow configurations, which make direct comparisons between the results difficult. A comparative study, based on the expression of the source terms as a function of the pressure, is presented in the present paper. This analytical approach demonstrates a large resemblance between the models, and it also clarifies the influence of the model parameters on the vaporization and condensation terms and, therefore, on the cavity shape and behavior. Some of the models were also tested using a 2D CFD code in configurations of cavitation on two-dimensional foil sections. Void fraction distributions and frequency of the cavity oscillations were compared to existing ...

Rotating shafts have a vast application in various industries especially in the aerospace industry such as engines, compressors and turbines. The researchers have performed considerable efforts on the rotating shafts' dynamic behavior because of their sensitivity to the rotor specifications and different parameters such as supports. In this paper by employing a pipe elbow element, an especial finite element formulation is derived to investigate dynamic behavior of rotating shaft in the presence of support clearance. The proposed element consists of four nodes with twenty-four degrees of freedom, which also accounts for the shear and gyroscopic effects. Within a finite element analysis framework, the focus of the paper is proposing a formulation to account for the dynamic behavior of a rotating shaft with much less number of elements. The element is implemented in a finite element code and then is used to model and analyze some rotating shaft examples. In order to verify the developed formulation, results are compared with those obtained from other schemes reported in the literature.

Rotating shafts have a vast application in various industries especially in the aerospace industry such as engines, compressors and turbines. The researchers have performed considerable efforts on the rotating shafts’ dynamic behavior because of their sensitivity to the rotor specifications and different parameters such as supports. In this paper by employing a pipe elbow element, an especial finite element formulation is derived to investigate dynamic behavior of rotating shaft in the presence of support clearance. The proposed element consists of four nodes with twenty-four degrees of freedom, which also accounts for the shear and gyroscopic effects. Within a finite element analysis framework, the focus of the paper is proposing a formulation to account for the dynamic behavior of a rotating shaft with much less number of elements. The element is implemented in a finite element code and then is used to model and analyze some rotating shaft examples. In order to verify the develope...

Geometric and material dispersions of bladed disks imply some mistuning effects, which result in both the loss of cyclic symmetry properties and a vibratory response amplification in areas of high modal density. These conditions complicate the prediction of vibratory behavior, causing high modal density and extreme sensitivity to mistuning. A non-intrusive spectral stochastic method has been developed to predict the vibratory behavior of a mistuned stator vane. To apply this method to an industrial model, a Karhunen-Loève expansion and a double modal synthesis method have been combined with the stochastic method. The complete method was first tested on a simple academic model and then on an industrial stator vane sector.

In the active magnetic bearings (AMBs) supported rotating machinery, touchdown bearings are considered as safety devices to support the rotor in the deficiency of electromagnetic field. Generally, the industrial AMB machines do not have force sensors for touchdown bearings and the system is only equipped with the position sensors to monitor the rotor displacement that disables the opportunity to measure the forces during dropdown events that might be destructive for the safe operation of the rotor system. This study explores the relative severity of dropdowns that are evaluated from a computational rotor model using the rotor displacement data recorded from the position sensors installed in the machine as an input. The model for double-row angular contact ball bearing type touchdown bearings is integrated with the rotor model. The simulation model is verified by comparing the simulated rotor orbits against measured orbits at four different dropdowns. The Fast Fourier transform (FFT) is used to observe the studied dropdown events in frequency domain revealing from the rotor response the following details: harmonics of the operation speed, rub-impact frequencies, pendulum motion of the rotor and the first two bending frequencies of the rotor settled on the touchdown bearings. The critical speed map also verifies the bending frequencies and identified support properties. The model-based approach can be used to evaluate and compare a single dropdown event with respect to previous events providing an insight for decision making whether touchdown bearing should be replaced.

This paper presents unsteady pressure and heat transfer measurements made on a high pressure turbine stage at DERA Pyestock, and compares them with numerical simulations made using the 2D unsteady code UNSFLO. The aim of the work was to evaluate the performance of the code, and to use the predictions to allow a fuller interpretation of the flow physics than could have been achieved from the measurements alone. The unsteady heat transfer and pressure fluctuations around the mid height section of the rotor blade have been examined in detail. Agreement between measured and predicted pressure fluctuations on the rotor was excellent. Interaction with the ngv potential field dominated the pressure surface, while the suction surface showed pressure waves moving forward over the blade, possibly as a result of shock/wake interaction.

This paper presents the application of optimization method developed by Hashimoto to design oil lubricated thrust bearings for 2.5 inch form factor hard disk drives (HDD). The designing involves optimization of groove geometry and dimensions. Calculations are carried out to maximize the dynamic stiffness of the thrust bearing spindle motor. Static and dynamic characteristics of the modeled thrust bearing are calculated using the divergence formulation method. Results show that, by using the proposed optimization method, dynamic stiffness values can be well improved with the bearing geometries not being fixed to conventional grooves.

The present study aims to combine the fields modal analysis and signal processing and to show the use of Frequency Response Function (FRF), as a vibration transfer path, in enhancing reliability and abilities of the next generation vibration-based rolling bearing condition monitoring (CM) systems in complex mechanical systems. In line with this purpose, the hereby-presented paper employs an appropriate numerical model, that is, Multibody Simulation (MBS) of a vehicle's drivetrain as a manner for numerical modal and structural analyses. For this, first, the principles of vibration-based bearing fault detection are reviewed and presented. Following that, a summary of MBS modelling and validating strategies are given. Then, the validated MBS model is used as a case study for further investigations. The results can confirm existence of challenges in fault detection of rolling bearings, in particular in complex mechanical systems. In further discussions, the capability of FRFs in fault localization and determination of ideal sensor positions is discussed in some detail. Finally, concluding remarks and suggestions for future works are summarized.

his presentation outlines the strategic importance of Maintenance Data Collection and the application of Reliability Centered Maintenance (RCM) at the Port of Fujairah. It begins with an overview of the evolution of maintenance practices from reactive to proactive approaches, emphasizing metrics such as MTBF, MTTR, and equipment availability. The core of the document details comprehensive methodologies for collecting and managing maintenance-related data—spanning design, operational, and maintenance history—across all system levels.

The presentation introduces structured procedures for failure data collection, including categorization by lifecycle stages (infant mortality, normal operation, wear-out) and the use of primary/secondary failure indicators. It stresses the need for system-level analysis over mere component replacement. Detailed case studies from mechanical and electrical maintenance incidents illustrate the application of failure mode analysis, the use of diagnostic tools, and structured problem-solving.

The document concludes with recommended practices for documentation, reporting, and root cause analysis, supported by international standards such as ISO 55000 and API 580/581. These practices aim to improve equipment reliability, enhance maintenance planning, and support long-term asset integrity.

curvature ratio of the cavity ⁄ , radial and tangential velocity components , dimensionless radial and tangential velocities Ω ⁄ , Ω ⁄ axial distance from the wall of the rotor inside the cavity dimensionless axial distance from the wall of the rotor inside the cavity ⁄ λ dimensionless geometrical parameter ⁄ Ω angular speed of the rotor ρ density of air kinematic viscosity of air

Rotors supported by cylindrical hydrodynamic journal bearings usually face rotational speed limitations due to the unstable motion caused by oil whip effect. An active magnetic bearing is utilized as auxiliary component to suppress oil whip and reduce unbalance lateral vibration amplitude at critical speed. Three distinct control methods are considered for the actuation force (dynamic H ∞ , μ synthesis, and polynomially parameter-dependent static H ∞ ), which must be designed to perform in a situation with varying parameters and uncertainties. These techniques are tested in scenarios with collocated and noncollocated feedback (emulating a magnetic actuator with magnetic flux sensors). The different resultant performances are successfully compared with each other numerically and experimentally.

This thesis presents the development and application of linear and non-linear sensitivity analysis techniques for determining the revised modal properties in a structural modification analysis using analytical or experimentally-derived modal data. Since the quality of experimentally-derived modal models is dependent on the accuracy and the reliability of measurement and structural identification techniques, the associated methods for frequency response function (FRF) measurement and structural identification are also presented. (noisy data) MAC values for the modified eigenvectors between the lst-order sensitivity analysis and the exact solution for the mass modification at point 6 MAC values for the modified eigenvectors between the Rayleigh quotient iteration and the exact solution for the mass modification at point 6 MAC values for the modified eigenvectors between the 1 St-order sensitivity analysis and the exact solution for the stiffness modification between points 3 and 4 MAC values for the modified eigenvectors between the Rayleigh quotient iteration and the exact solution for the stiffness modification between points 3 and 4 Comparison between the modal properties obtained from the proposed technique and the exact solution Case 1 : Added mass at node 4 Comparison between the modal properties obtained from the proposed technique and the exact solution Case 2 : The width of the diagonal bar was reduced by a factor of 40% and three 0.15kg masses were attached to nodes 4, 10 and 17 respectively. Comparison between the modal properties obtained from the proposed technique and the exact solution Case 2 : The width of the diagonal bar was reduced by a factor of 40% and three 0.15kg masses were attached to nodes 4, 10 and 17 respectively. (18 modes of the original system have been used) 156 156 172 174 ;.

The reluctance synchronous motor performance highly depends on its saliency ratio. Therefore an accurate analytical calculation of the motor's saliency is quite a necessity within the designing procedure. In this paper an analytical method to calculate the main motor inductances and its saliency ratio is applied to a segmented rotor reluctance synchronous motor. The results obtained for two motor variants, compared with the ones obtained via a 2-D FEM computation and via tests, stand by to prove the proposed technique accuracy.

Artykuł publikowany w 2020 stał się dziś szczególnie aktualny w związku z tym, że przybywa źródeł energii odnawialnej, które wytwarzają prąd zależnie od pogody. Główne źródło trudności, którą omawiam, wiąże się z faktem, że zarówno ilość produkowanej energii, jak i jej zużycie stale się zmieniają. Ideałem jest sytuacja, gdy produkujemy tyle energii, ile w danym momencie klienci wykorzystają. Ale ten ideał bardzo trudno osiągnąć, bo mimo naukowych metod prognozowania zapotrzebowania na energię (sam się tym zajmowałem przy użyciu sieci neuronowych)-rzeczywistość często rozmija się z oczekiwaniami. Szczególnie trudna sytuacja powstaje, gdy potrzeby przewyższą produkcję. Trzeba wtedy wyłączać niektórych odbiorców, co jest nieprzyjemne i wiąże się ze stratami ekonomicznymi. Dlatego energii produkuje się zawsze trochę więcej, niż przewidywane zapotrzebowanie. Ale jeśli klienci tej nadwyżki energii nie kupią-to pojawia się problem. W przypadku innych towarów można nadmiar zmagazynować i sprzedać w momencie, gdy ponownie popyt przewyższy podaż. W przypadku energii elektrycznej magazynowanie jest bardzo trudne.

The study of dynamic behavior of rotating parts have significant role to the operating mechanism and failure associated with vibration. Shaft and runner are the main component of water turbines which are subjected to highly difficult working conditions. When rotors are operating at high speeds centrifugal actions cause to increase intensity of vibration. During the manufacturing and installation dynamics analysis is necessary. This research work was focused on modeling of Pelton turbine unit; which cover dynamic behavior of overhung rigid runner on circular flexible shaft, which was supported by rigid bearings on one end and enable to determine the natural frequency of the system by using different models. The unit was modeled as discrete and continuous systems. Simplified Jeffcott rotor model and Rayleigh’s energy method: effective mass models were used for the discrete system models. The model for continuous system was developed by calculating the kinetic and potential energy of t...

This 74-in-diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil-film bearings and was directdriven by a 3000-hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system. Although the blowers showed very satisfactory vibration levels during test runs at the manufacturer's plant, the vibration levels in situ had always been higher than was desirable. After several months of monitoring showed ever increasing vibration levels, one of the blowers was shut down in order to diagnose and resolve the problem. Several steps were taken to diagnose the problem: (1) The rotor was removed and the shop balance was checked and corrected. (2) The bearing support movement due to thermal expansion was measured. Then the shafts were misaligned in the cold condition in order to achieve near-perfect shaft alignment during normal operation. (3) The expected shaft vibration at the bearings was determined using lateral rotor dynamics analysis, including critical speed mapping. (4) A heavy sleeve was added to the blower shaft to increase the radial load on the drive-end bearing. (5) The metal disk type of coupling was replaced by a gear coupling. (6) The finite element and impact of the bearing support pedestal were tested to determine the stiffness of the bearing support. (7) The shaft movement was measured during a coast-down. (8) Tilting-pad bearings were evaluated as a possible replace-

This 74-in-diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil-film bearings and was directdriven by a 3000-hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system.Although the blowers showed very satisfactory vibration levels during test runs at the manufacturer's plant, the vibration levels in situ had always been higher than was desirable. After several months of monitoring showed ever increasing vibration levels, one of the blowers was shut down in order to diagnose and resolve the problem.Several steps were taken to diagnose the problem: (1) The rotor was removed and the shop balance was checked and corrected. (2) The bearing support movement due to thermal expansion was measured. Then th...

We examine the dynamics of a healthy rotor and a rotor with a transverse crack, which opens and closes due to its self weight. Using discrete wavelet transform, we perform a multiresolution analysis of the measured vibration signal from each of these rotors. In particular, the measured vibration signal is decomposed into eight frequency bands, and the rms amplitude values of the healthy and cracked rotors are compared in the three lowest-frequency bands. The results indicate that the rms vibration amplitudes for the cracked rotor are larger than those of the healthy rotor in each of these three frequency bands. In the case of externally applied harmonic force excitation to the rotor, the rms values of the vibration amplitude of the cracked rotor are also found to be larger than those of a healthy rotor in the three lowest-frequency bands. Furthermore, the difference in the rms values between the healthy and cracked rotors in each of the three lowest-frequency bands is more pronounced in the presence of external excitation than that with no excitation. The obtained results suggest that the present multiresolution approach can be used effectively to detect the presence of a crack in a rotor.

We examine the dynamics of a healthy rotor and a rotor with a transverse crack, which opens and closes due to its self weight. Using discrete wavelet transform, we perform a multiresolution analysis of the measured vibration signal from each of these rotors. In particular, the measured vibration signal is decomposed into eight frequency bands, and the rms amplitude values of the healthy and cracked rotors are compared in the three lowest-frequency bands. The results indicate that the rms vibration amplitudes for the cracked rotor are larger than those of the healthy rotor in each of these three frequency bands. In the case of externally applied harmonic force excitation to the rotor, the rms values of the vibration amplitude of the cracked rotor are also found to be larger than those of a healthy rotor in the three lowest-frequency bands. Furthermore, the difference in the rms values between the healthy and cracked rotors in each of the three lowest-frequency bands is more pronounced in the presence of external excitation than that with no excitation. The obtained results suggest that the present multiresolution approach can be used effectively to detect the presence of a crack in a rotor.

Achard turbine is one kind of vertical axis water turbine that can use to low head water current. Achard turbine can use to river flow or irrigation canal. This is will make an additional function of river and irrigation canal to be a renewable energy resource. The experiment use three blades NACA 0020 Achard turbine in the irrigation canal at Belitang District, West Ogan Komering Ulu. The flow current is 0.55 m/s, 0.61 m/s, and 0.71 m/s. The result shows increasing of CP and CT by increasing of flow current. Maximum CP is 0.1797 at flow current 0.71 m/s. Maximum CT is 0.206 at flow current 0.71 m/s.

Achard turbine is one kind of vertical axis water turbine that can use to low head water current. Achard turbine can use to river flow or irrigation canal. This is will make an additional function of river and irrigation canal to be a renewable energy resource. The experiment use three blades NACA 0020 Achard turbine in the irrigation canal at Belitang District, West Ogan Komering Ulu. The flow current is 0.55 m/s, 0.61 m/s, and 0.71 m/s. The result shows increasing of C P and C T by increasing of flow current. Maximum CP is 0.1797 at flow current 0.71 m/s. Maximum C T is 0.206 at flow current 0.71 m/s.

This paper aims to experimentally investigate the non-uniform velocity field on the suction elbow outlet of the large pumps. The suction elbow has a threedimensional symmetrical shape that induces non-uniform hydrodynamic field at the impeller inlet. The velocity field is measured using LDV system in order to be quantified the non-uniformities generated at the impeller inlet. A large variation of the circumferential velocity component induces a significant modification of the absolute angle flow in front of the impeller over each full rotation. Therefore, strong unwanted effects are generated in the impeller. The conclusions are drawn in the last section.

This paper presents a multiobjective optimization procedure for a two-blade impeller in a sewage pump with a
stationary front shroud. The optimization variables were the wrap angles on the front and back shroud, while the
meridional cross-section and volute remained constant. The objective was to maximize efficiency, head, and free
passage (e.g., minimizing blockage) while minimizing vibrations by reducing radial forces. A full factorial design with
five levels was used for CFD (computational fluid dynamics) calculations. After selecting the optimal design, the results
of initial and optimized impeller were validated experimentally. Numerical and experimental results demonstrated
good agreement. The optimized impeller showed improvements: head increased by 38,4%, efficiency by 9,5%, and
free passage by 8,3%. While CFD calculations predicted a reduction in averaged radial forces, vibration
measurements on volute indicated an increase for the optimized impeller by 46,1%. This discrepancy suggests that
radial forces may not be the primary factor influencing vibrations in this specific pump configuration. The findings of
this study contribute to the development of more efficient and reliable sewage pumps.

This paper deals with the maintenance technique for industrial machinery using the artificial neural network so-called self-organizing map (SOM). The aim of this work is to develop intelligent maintenance system for machinery based on an alternative way, namely, thermal images instead of vibration signals. SOM is selected due to its simplicity and is categorized as an unsupervised algorithm. Following the SOM training, machine fault diagnostics is performed by using the pattern recognition technique of machine conditions. The data used in this work are thermal images and vibration signals, which were acquired from machine fault simulator (MFS). It is a reliable tool and is able to simulate several conditions of faulty machine such as unbalance, misalignment, looseness, and rolling element bearing faults (outer race, inner race, ball, and cage defects). Data acquisition were conducted simultaneously by infrared thermography camera and vibration sensors installed in the MFS. The exper...

-Vlll -* Magnitude of the pressure fluctuations. * Magnitude of the fluctuating lift . * Difference in the pressure fluctuations caused by full and partial blades. * Dependence of the magnitude of the pressure fluctuations on the radial gap between the impeller blades and the diffuser vanes. It was found that: * The largest pressure fluctuations, of the same magnitude as the total pressure rise across the pump, occurred on the vane suction side close to the leading edge. * The pressure fluctuations were largest for maximum flow. * The pressure fluctuations were larger on the suction than on the pressure side. * Increasing the radial gap between impeller blades and diffuser vanes from 1.5% to 4.5% resulted in a significant decrease, especially of the large pressure fluctuations on the front half on the suction side.

This paper describes an investigation of rotor/stator interaction in centrifugal pumps with radial diffusers. Steady and unsteady diffuser vane pressure measurements were made for two impellers, one half of the double suction pump of the High Pressure Oxygen Turbopump (HPOTP) of the Space Shuttle Main Engine (SSME) and a two-dimensional impeller. Unsteady impeller blade pressure measurements were made for a second two-dimensional impeller with blade number and geometry identical to the two-dimensional impeller used for the diffuser vane pressure measurements. The experiments were conducted with different flow coefficients and different radial gaps between the blade trailing edge and the diffuser vane leading edge (5% and 8% of the impeller discharge radius for the two-dimensional impellers, and 1.5% and 4.5% for the impeller of the HPOTP). The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. On the diffuser vanes, the largest pressure fluctuations were observed on the suction side of the vane near the leading edge, whereas on the impeller blades the largest fluctuations occurred at the blade trailing edge. The resulting lift on the diffuser vane was computed from the pressure measurements; the magnitude of the fluctuating lift was found to be larger than the steady lift.