Mechanical failures

Ships' propulsion plant usually works in a hard environment caused by static forces and permanent dynamic loads. Basic elements of propulsion systems are rotation machines like gas turbine engines, gear boxes, propulsion shafts etc. Another loads coming from technological faults of rotation machines like misalignment, unbalancing or resonance. Exciding of tolerated values of shaft alignments or unbalancing can cause a damage of radial and thrust bearings in relative short time. Similar situation is occurred when the mode or modes of rotors natural resonances are in the range of operational speed. The paper compares three methods of calculating and recognizing modes of rotors' natural frequencies using laboratory model of rotational machine. Results of FEM modeling, modal hammers measurements and synchronous vibration measurement show that free stop-down process is an interesting area for the vibration diagnosing of rotational machines.

Vibration tests of marine gas turbine engines are performed as researches on-line and off-line types. The paper presents analyses of both methods. Results of tests were received on three types of gas turbine engines operated in the COGAG type propulsion systems. The application of periodical diagnostic procedures or on-line monitoring systems makes it possible to operate ship propulsion systems in accordance with their current technical state. In the case of ship gas turbines the hourly period of scheduled maintenance or repair surveys is presently the criterion for maintenance time determination. The Finite Element Analysis (FEA) is used for confirmation actual technical state. FEA are used successfully for a wide range of problems and it may also be used for the modelling and analysis of rotor system. Presently, the diagnostics team uses FEA and the modelling of rotordynamics in conjunction with vibration analysis for detection and identification of unbalancing. Main goal of researches was qualified of helpfulness and unequivocally results received by methods of synchronous measurement, order tracking and auto tracking. All vibration symptoms were chosen from the methodology of the diagnosing gas turbine engines operated in the Polish Navy, called BDS (Base Diagnosing System). This element of BDS is accepted and used in all ships of Polish Navy, which are powered by the COGAG power plant. Second purpose of researches was estimation of the possibility of implementation presented methods of vibration analyses of gas turbine engines fornew, modern on-line monitoring system. The proposed diagnostics method makes it possible to determine the limiting value of vibration symptoms witch, if exceeded, indicates the inadmissible axis slope value between rotated machines of gas turbine engine and, moreover , it provides an unambiguous relationship between the value of symptom of rotors unbalance and the rotors rotational speed.

The paper is devoted to the development of the refined numerical and mathematical models of rotor dynamics for high-performance turbomachines. These models consider the nonlinear regression dependencies between the radial stiffness of bearing supports and rotor speed of the shaft. As a result of the comprehensive application of the proposed approach, the algorithms of identification of the stiffness parameters of the bearing supports were proposed based on the critical frequencies of the rotor system. Additionally, the methodology for estimating the system of initial imbalances by the related displacements of the rotor axis in the correction and calculation cross-sections was improved. The proposed approaches based on the comprehensive application of the CAE software and computational intelligence systems allow conducting the modal and harmonic analysis and realizing the virtual balancing with the significant decrease of the preparatory and machine times without the loss of relative accuracy. Additionally, the developed mathematical models of free and forced oscillations of rotor systems were implemented as a program code of the operating files "Critical frequencies of the rotor" and "Forces oscillations of the rotors" within the computer algebra system that allows improving the dynamic balancing procedure in order to estimate the system of initial imbalances. The high accuracy of the proposed approach is confirmed by the verification of dynamic deflections of the rotor axis by the system of residual imbalances in accordance with the norms of vibration reliability.

The present study focuses on elucidating the fundamental reasons underlying the emergence of vibrations in steam turbines. During operation, vibrations are observed not only in the components of the machinery that undergo cyclical motion but also in those components connected to the equipment. Therefore, vibration monitoring holds great importance in identifying malfunctions in the functional operations of turbomachinery, enabling timely detection and prevention of potential accidents. Using the steam turbine unit as an example, it is noteworthy that the rotor primarily undergoes oscillatory motion, where it is essential to recognize that vibrations also manifest in bearings, housings, turbine foundations, pipelines and surrounding components. The thorough examination of vibration should encompass not only turbine rotors but also the entire turbine assembly, including the generator and all associated equipment. It is essential to conduct a comprehensive evaluation of the overall system to ensure optimal functionality. Academic research papers typically do not often assess the specific number of working hours and conditions which are leading to rotor damage, also in that sense, not determining if damage is a result of wear and tear during prolonged undesired operation. Instead, the emphasis is commonly placed on analyzing elevated levels of vibrations and investigating the associated occurrence of cracks. This paper aims to provide a comprehensive summary of the main causes of vibrations through a unified perspective on the various conclusions available, regarding the diverse causes behind these common and complex vibration occurrences.

The usage of industrial steam turbines in different industrial branches (chemistry, petrochemistry, refineries, sugar and ethanol plants, etc.) for a generator drive for electricity generation or a mechanical drive for compressors, blowers and pumps, is characterized by the need for high flexibility of operation. High flexibility includes numerous start-ups, shutdowns and power changes during the useful life. Changes in power and steam mass flow lead to changes of the working fluid state in the single turbine stages, and thus their aerodynamic and thermodynamic characteristics. During these transient working regimes in steam turbine rotors, large space and time-dependent temperature gradients appear, which can result in high non-stationary temperature stresses, i.e. increased local stress concentrations, what has a negative impact on the useful life of the rotor. In the worst case they can cause fracture of the turbine rotor. Today, for the determination of thermal stressed state of the steam turbine parts the user softwares based on numerical methods are used. In this paper the results of numerical modelling and calculations of non-stationary temperature fields and related stresses in the rotor of industrial steam turbine of 35 MW power during transient operating regime (a cold startup) will be presented. The results of the calculations serve for estimation of the transient regime impact on the stresses of the rotor, as well as on its entire useful life.

The present study focuses on elucidating the fundamental reasons underlying the emergence of vibrations in steam turbines. During operation, vibrations are observed not only in the components of the machinery that undergo cyclical motion but also in those components connected to the equipment. Therefore, vibration monitoring holds great importance in identifying malfunctions in the functional operations of turbomachinery, enabling timely detection and prevention of potential accidents. Using the steam turbine unit as an example, it is noteworthy that the rotor primarily undergoes oscillatory motion, where it is essential to recognize that vibrations also manifest in bearings, housings, turbine foundations, pipelines and surrounding components. The thorough examination of vibration should encompass not only turbine rotors but also the entire turbine assembly, including the generator and all associated equipment. It is essential to conduct a comprehensive evaluation of the overall system to ensure optimal functionality. Academic research papers typically do not often assess the specific number of working hours and conditions which are leading to rotor damage, also in that sense, not determining if damage is a result of wear and tear during prolonged undesired operation. Instead, the emphasis is commonly placed on analyzing elevated levels of vibrations and investigating the associated occurrence of cracks. This paper aims to provide a comprehensive summary of the main causes of vibrations through a unified perspective on the various conclusions available, regarding the diverse causes behind these common and complex vibration occurrences.

Key words: Steam turbine vibration, vibration causes, vibration emergence

The objective of our work is the association of vibratory diagnosis knowledge with an acoustic part including frequential and spatial criteria for the identification of noise sources in rotating machinery. To control parameters for this difficult problem, one proceeds by stages and with confrontation of theoretical and experimental methods. This paper presents the theoretical modelling of a rotor on bearings system, with a simulation of several defects such as misalignment, imbalance and defective bearings. Pressure field calculations are performed with the help of an effective method based on modelling a structure by a set of point sources placed on the radiating surface.

The objective of our work is the association of vibratory diagnosis knowledge with an acoustic part including frequential and spatial criteria for the identification of noise sources in rotating machinery. To control parameters for this difficult problem, one proceeds by stages and with confrontation of theoretical and experimental methods. This paper presents the theoretical modelling of a rotor on bearings system, with a simulation of several defects such as misalignment, imbalance and defective bearings. Pressure field calculations are performed with the help of an effective method based on modelling a structure by a set of point sources placed on the radiating surface.

The interactions between rotor-stator submerged in incompressible fluid flows are strong nonlinear phenomena that have wide applications in scientific and engineering disciplines. This paper presents vibration analysis of a vertical oscillating rotor-rub system interacted in incompressible flow regimes. The governing equation of the coupled lateral and torsional vibrations of a rotor-rub system and the inviscid fluid forces action are firstly established based on Energy Principle and Euler method for the incompressible fluid. The unsteady 5-Degree-of-Freedom system of rotorstator-fluid motion is simulated by means of an appropriate solver. In the analysis it was found througth the severity of the fault detected that the presence of inviscid fluid gives strong softening and fluctuating interferences components in the response when the rotating system is involved in rotor-stator contact. Further, the responses displayed a generally softening nonlinearity on torsional deflection of the rotor. The results reveal that, the inviscid fluid had a significant attenuation on the orbit of the shaft in comparison to a standard orbit of the rotor. The obtained results indicate that the fluid-rotor interaction considerably reduce the dynamic vibration response of the faulted rotor system.

This article analyses the main characteristics of marine power plants, which include internal combustion engines (ICE) and gas turbine engines (GTE). At the same time, gas turbines are considered in comparison with aircraft engines. The study considers the possibility of using the acoustic emission (AE) method to evaluate the fatigue resistance of critical elements of ICE and GTE, based on the valve block in the ICE and turbine rotor blades. AE criteria for determining the growth of fatigue cracks are analysed, a method for evaluating individual durability and a method for calculating crack length are proposed.

Turbo machines develop faults in the rotating blades during operation in undesirable conditions. Such faults in the rotating blades are fatigue cracks, mechanical looseness, imbalance, misalignment, etc. Therefore, it is crucial that the blade faults should be detected and diagnosed in order to minimize the severe damage of such machines. In this paper, vibration analysis of the rotating blades is conducted using an experimental laboratory setup in order to develop a methodology to detect faults in the rotating blades. The faults considered for the study include cracks and mechanical looseness for which dynamic responses are recorded using a laser vibrometer. Analysis has been carried out by comparing the frequency response function spectrums of the fault blade with those of the healthy blade related to the resonance frequency. The Internet of Things and wireless sensor networks are implemented to transmit the measured data to the cloud platform. A support vector machine algorithm i...

it is well known that old design high-power genera ting machines were on duty for more than 35-40 years and will successfully continu e operation after proper renovations and overhauls. this paper considers vibrational charact e istics of the old continuously operated 110 mw turbounit with steam turbines and electric gener ator rotating system running at nominal speed of 3000 rpm. vibration and technological para meters were systematically monitored in the course of 5 years after installation of condition m onitoring and diagnostics system, which is based on measurements of rotor relative vibration d isplacement. it is demonstrated that application of optimized vibration monitoring and d iagnostic system and several vibration data formats is effective in evaluation of overhaul qual ity through vibration severity of rotor system and identification of causes of these vibrations. t he research focus in the reported research work is placed on inspection of mechanical effect of hor izont...

Be it in land, air or sea; shaft coupling or flexible joint remains a precarious constituent in any vehicular system. In arrears to its substantial expediency, this paper imparts a one-off flexible joint design predominantly dedicated to drive the main rotor shaft of a single-seat helicopter. An inimitable experiment is conceived and piloted by constructing a dedicated test rig which is capable of assessing the flexible joint at different rotational speeds providing a conduit to comprehend its functionality. Comparative data accumulated through both with and without the implementation of the flexible joint revealed that the coupling unremittingly assists is reducing vibration at higher speeds accompanied by common phenomenon of resonance at certain rpm. Nevertheless, the prototype flexible joint is believed to have substantiated its significance through perpetual power transmission including improved vibrational stability.

Alexander Lifson is currently employed by Chandler Evans Corpora­ tion as a Section Engineer. In his present position, he is responsible for directing analytical research activities in the area of aircraft fuel pump performance. Prior to joining Chandler Evans, he worked for Southwest Research Institute in the areas of acoustics, rotordynamics, compressor flow simulation, fluid me­ chanics, and vibration/stress analysis of machine parts and piping components. B efore joining Southwest Research Institute, Mr. Lifson was employed by Exxon Research and Engineering Company, where he was responsible for performing rotordynamic studies, for simulating compressor operation, and for the acceptance of mechanical and performance tests of compressor trains. Mr. Lifson received his B . S. degrees in Mechanical Engineer­ ing and Mathematics from Leningrad Polytechnic Institute (1978), and his M. S. degree in Mechanical Engineering from MIT (l981) .

This paper studies the detection of twisted blade in a multi stages rotor system. Experimental study was undertaken to simulate twisted blade conditions in a three stages rotor system. The feasibility of vibration analysis as the technique to detect twisted blade based on the rotor operating frequency and its blade passing frequency was investigated in this study. Experimental results show that twisted blade can be easily detected by looking into the pattern of the vibration spectrum and its individual peaks.

Intralogistic systems consist of several mechanical components which undergo wear during operation and can fail. To avoid failure critical components will be replaced in planned intervals (preventive maintenance). By contrast, in case of maintenance with condition monitoring such components are monitored by non-destructive testing and not replaced while no critical state is reached. The aim of present work is to find suitable sensors and calibrate them. For this, components are mechanical tested with a servohydraulic test equipment until failure based on pre-determined use and load profiles.

This paper presents the occurrence of torsional vibrations of mechanical systems and instruments for measuring and analyzing natural frequencies and modal forms of torsional vibrations, maximum angular deflections and their relationship for certain rotational speeds and characteristic damage frequencies. Traditional but modern measurement and analysis methods and procedures are shown to help detect increased torsional stresses to prevent expected system failures.

Strength consideration of concrete with ages has influence sourcing for suitable materials, which can be added to concrete in small quantities without leaving adverse effect on the properties of fresh and hardened concrete. This project examines the possib ility of using limestone as an additive, replacing fine aggregate in small quantity in concrete production. The experiment includes si eve analysis which gives a well graded fine aggregate, slump test, compression test, and water absorption rate. The slump result gives a less workable concrete on the addition of limestone in concrete while the water absorption rate of concrete increases on the addition of limestone in concrete mix. The strength attained after 7 and 28 curing days shows that , limestone can be added to concrete in 5% to 10% replacement of sharp sand, in which there is tendency to achieve higher strength with ag

Autonomous intersection management (AIM) is a new intersection control protocol that exploits the capabilities of autonomous vehicles to control traffic at intersections in a way better than traffic signals and stop signs. A key assumption of this protocol is that vehicles can always follow their trajectories. But mechanical failures can occur in real life, causing vehicles to deviate from their trajectories. A previous approach for handling mechanical failure was to prevent vehicles from entering the intersection after the failure. However, this approach cannot prevent collisions among vehicles already in the intersection or too close to stop because (1) the lack of coordination among vehicles can cause collisions during the execution of evasive actions; and (2) the intersection may not have enough room for evasive actions. In this paper, we propose a preemptive approach that pre-computes evasion plans for several common types of mechanical failures before vehicles enter an intersection. This preemptive approach is necessary because there are situations in which vehicles cannot evade without pre-allocation of space for evasion. We present a modified AIM protocol and demonstrate the effectiveness of evasion plan execution on a miniature autonomous intersection testbed.

MGT-70(3) gas turbine is the recent upgraded version of MGT-70 gas turbine family introduced by MAPNA Turbine Engineering & Manufacturing Co. (TUGA). Due to the vast upgrade regards to its predecessor engine, MGT-70(3) required to be tested extensively in order to examine the functionality of the engine as well as verification of the CFD calculations. Therefore, a detailed component test designed and implemented. A set of large number of sensors, both in quantity and type, utilized in almost all stages of turbine, compressor and combustion chamber. Testing both the static and dynamic behaviour of the engine was favourable. Thermocouples and pressure sensors have been used for static measurements while 5-Hole Probes and strain gauges for dynamic behaviors. A BTT/BTC measuring system is also installed on some stages for BTT/BTC measurements. The results demonstrated that all performance targets have been met and even exceeded in some indexes.

This paper studies the detection of twisted blade in a multi stages rotor system. Experimental study was undertaken to simulate twisted blade conditions in a three stages rotor system. The feasibility of vibration analysis as the technique to detect twisted blade based on the rotor operating frequency and its blade passing frequency was investigated in this study. Experimental results show that twisted blade can be easily detected by looking into the pattern of the vibration spectrum and its individual peaks.

This paper presents an analysis of nonsynchronous rotor blade vibrations in the last stage of an LP steam turbine at various condenser pressures. The nonlinear least squares Levenberg–Marquardt method is used in a tip-timing analysis to determine nonsynchronous multimode rotor blade vibrations, which is a novelty. This is done with two sensors in the casing and a once-per-revolution sensor. The accuracy of the nonlinear least squares Levenberg–Marquardt multimode method is compared with the one-mode linear method. The algorithm is verified by comparing it with one-mode tip-timing methods for synchronous and nonsynchronous vibrations. The analysis shows that the rotor blades vibrate simultaneously with two modes in non-nominal conditions, which is also a novelty. The rotor frequencies are unchanged, although the blade vibration amplitudes vary, depending on the pressure in the condenser. Flutter does not appear in the last stage for the various condenser pressures and powers that wer...

This paper provides a critical and analytical assay in the process vicinity of an Organic Rankine Cycle (ORC) resulting in a representation of a controlling model named as Spiral Model as the best approach to implement for an efficient Plant Management (PM) and Risk Mitigation Planning (RMP), focusing on the robust and elegant energy production. There have been so many predictive and sensing process models presented for a gist and substantial control of the ORC plant in recent years but the proposed Spiral Predictive Model (SPM), eliminating all the limitation of all previously implemented models, provides the robustness by performing all the roles in increments; e.g. in the changing controllers, complex time-frequency characteristics, fault detectors for turbines against disruptions and the multi-switching techniques needs to be cascaded ahead of time with predictive and detective techniques. The proposed model optimizes the performance of ORC by response tracking and recursive correction which relegates the errors and sudden disturbance in the process flow. Fast response and recursive correction nicely handles Demand Response (DR) and parameters variations at different working modules which ultimately provide the dynamic performance capability. This study will be elaborating efficient model design and implementation to conjure up a well-designed working flow in an ORC plant.

A turbomachine is a fundamental engineering apparatus meant to transfer energy between a rotor and a fluid. Turbomachines are the core of power generation in many engineering applications such as electric power generation plants, aerospace, marine power, automotive etc. Their relevance makes them both mission critical and safety critical in many fields. To foster reliability and safety, then, continuous monitoring of the rotor is more than desirable. One promising monitoring technique is, with no doubt, the Blade Tip-Timing, which, being simple and non-invasive, can be easily implemented on many different rotors. Blade Tip-Timing is based on the recording of the time of arrival of the blades passing in front of a probe located at a fixed angular position. The non-contact nature of the measurement prevents influences on the measured vibration, that can be recovered for all the blades simultaneously, possibly even online. In this regard, a novel algorithm is presented in this paper fo...

The vibration phenomena which occur in rotary machines, such as power plants, can result in catastrophic consequences. Any failure in any power plant section can result in extended downtime and high repair expenses. Vibration is one of the most common causes of power plant failure. The above-mentioned issues can be avoided using high-accuracy vibration detection and prediction technologies. Therefore, further research into the primary causes of vibration on Combined Cycle Power Plants (CCPPs) can help improve the present vibration evaluation methodologies for power plants. This paper aims to survey some of the most commonly reported factors that can induce vibration in the gas turbine of CCPP. Therefore, this paper aims at reviewing the unbalancing and misalignment, contact among rotating and stationary components (rubbing), steam flow fluctuations, the rotor critical speed, and shorted-turns, which are some of the most common destructive vibrations in this industry. Furthermore, some of the most used well-known technologies for vibration monitoring and evaluation in the gas turbine of CCPPs are described, such as proximity probes, laser Doppler vibrometer, eddy current sensor, and accelerometer, which can be used to create a maintenance time schedule for the gas turbine of CCPPs and also, it helps to reduce maintenance time and power generation costs.

This paper describes two steam turbine governor valve failures in the same installation, the troubleshooting that determined the root cause, and the new valve designed to prevent similar failures. The original governor valve design had been used successfully for many years in large multistage, multivalve steam turbines, but apparently was not reliable at the high steam pressures employed today. Mechanical analyses, flow analyses, and testing showed that the failures were caused by flow-induced instability in the valve. Candidate valves with more stable flow fields were designed and tested. The final design combined features of two other, more typical designs, and showed good flow stability throughout the lift range. This new “hybrid” valve has since been applied successfully

En la presente investigación se realiza la explicación de la metodología aplicada a la determinación de la presión máxima de compresión de un motor de combustión interna alternativo de encendido provocado (MEP), el cual se basa en un estudio que parte de la caracterización de las curvas del consumo de amperaje del motor de arranque. Se aplica un protocolo de adquisición de datos y su posterior análisis estadístico. Los valores estadísticos de la señal como energía, promedio, desviación estándar, varianza, kurtosis, asimetría, máximo, mínimo y factor de cresta son seleccionados en función al mayor aporte de información para la caracterización del experimento; estos valores generan bases de datos las cuales son aplicadas para la creación y entrenamiento de una red neuronal artificial recurrente (RNAR) en la cual se obtiene un error absoluto menor al 2 %. En una primera instancia se aplica la metodología de pruebas en un motor ensamblado en un banco didáctico y luego se procede a la ap...

This research explains the methodology for the creation of a diagnostic system applied to the detection of mechanical failures in vehicles with gasoline engines through artificial neural networks. The system is based on the study of the intake phase of the Otto cycle, which is recorded through the physical implementation of a MAP sensor (Manifold Absolute Pressure). A strict sampling protocol and its corresponding
statistical analysis are applied. Statistical values of the MAP sensor signal such as, area, energy, entropy, maximum, mean, minimum, power and RMS, were selected according to the greater amount of information
and significant difference. The data were obtained with the application of 3 statistical methods (ANOVA, correlation matrix and Random Forest) to create a database that allows the training of a neural network feed-forward backpropagation, with which a classification error of 1.89 e−11 was achieved. The validation of the diagnostic system was carried out by the generating supervised failures in different engines
with provoked ignition.

En la presente investigación se explica la metodología para la creación de un sistema de diagnóstico aplicado a la detección de fallas mecánicas en vehículos con motores a gasolina mediante redes neuronales artificiales, el sistema se basa en el estudio de la fase de admisión del ciclo Otto, el cual es registrado a través de la implementación física de un sensor MAP (Manifold Absolute Pressure). Se emplea un estricto protocolo de muestreo y su correspondiente análisis estadístico. Los valores estadísticos de la señal del sensor MAP: área, energía, entropía, máximo, media, mínimo, potencia y RMS se seleccionaron en función al mayor aporte de información y diferencia significativa. Los datos se obtuvieron con la aplicación de 3 métodos estadísticos (ANOVA, matriz de correlación y Random Forest) para tener una base de datos que permita el entrenamiento de una red neuronal feedforward backpropagation, con la cual se obtiene un error de clasificación de 1.89e−11. La validación del sistema de diagnóstico se llevó a cabo mediante la provocación de fallas supervisadas en diferentes motores de encendido provocado.

En la presente investigación se realiza la explicación
de la metodología aplicada a la determinación de
la presión máxima de compresión de un motor de
combustión interna alternativo de encendido provocado
(MEP), el cual se basa en un estudio que parte
de la caracterización de las curvas del consumo de
amperaje del motor de arranque. Se aplica un protocolo
de adquisición de datos y su posterior análisis
estadístico. Los valores estadísticos de la señal como
energía, promedio, desviación estándar, varianza, kurtosis,
asimetría, máximo, mínimo y factor de cresta
son seleccionados en función al mayor aporte de información
para la caracterización del experimento; estos
valores generan bases de datos las cuales son aplicadas
para la creación y entrenamiento de una red neuronal
artificial recurrente (RNAR) en la cual se obtiene un
error absoluto menor al 2 %. En una primera instancia
se aplica la metodología de pruebas en un motor
ensamblado en un banco didáctico y luego se procede
a la aplicación del método en motores aplicados en
vehículos.

A failure in the bottom sheet of a bucket conveyor (KZBQ.AUMUND)
during service was investigated. Sheets are
coupled to the chain throught a screw connection; they
operate in variable load scenarios causing fatigue. A
chemical and microstructural analysis was made showing
that sheet was built in steel with 0.15 % of Carbone without
alloying elements that contribute to the refined grain and
resistance increase. Strength calculation, used to
determinate safety factor, consider load system and type
material. Results concluded that geometry and thickness
value do not provide an adequate fatigue resistance
coefficient.

The existence of unsteady states of rotary machines is a common problem. It occurs mainly during the machine start-up and is caused by “passing through” the critical velocity, which activates large scale object vibrations. Moreover, rotary machines vibrations problems are caused by faults such as unbalance, misalignment, bearing defects and others. The paper presents the results of tests of sample centrifugal fans vibrations, both in steady and unsteady states. The recorded time traces of non-stationary vibrations were analyzed with the STFT spectrum. This method allowed to identify main parameters influencing the level of vibrations during the start-up and regular operation of the machine. The tests were performed on four machines, which enabled an additional comparison of operational parameters of the whole flow system.