Process Industries

Background: Fire and explosion in process industries can have catastrophic consequences. The frequency of these accidents has led safety experts to underscore the importance of conducting thorough risk analysis studies to implement effective control measures. Materials and Methods: A tank gas leak was initially selected as a scenario for probable explosion risk assessment. The bowtie technique was utilized to analyze the potential causes and consequences of the selected incident. A fuzzy logic approach was used to quantify the probability of essential events, and the Bayesian network (BN) was employed for dynamic risk analysis. Results: Using the bowtie method, 24 fundamental causes were identified for tank gas leaks (main scenario). Moreover, 4 safety barriers against the prevention of the selected scenario were identified, and evaluation of the success and failure of these safety barriers led to the identification of 5 potential consequences. According to the BN and fuzzy analysis, the inappropriate installation was the most influential event, with a near miss identified as the most likely consequence of the central event. Conclusion: The results demonstrate that applying fuzzy logic and BNs could solve the uncertainty and static nature of traditional quantitative risk analysis studies.

Special issue of the journal on loss prevention in the process for the world conference on Chemical Engineering in 2017 in Barcelona, Spain According to the Declaration of Barcelona on occasion of the 10th World Congress of Chemical Engineering held between 1 October and October 5, 2017 in Barcelona, Spain, the promotion of safety, like the conservation and care of global resources, health, and the environment, is one of the four key-points to improve the quality of life, foster employment, advance economic and social development and protect the planet through sustainable development. The Declaration of Barcelona signed by the President of the "World Council of Chemical Engineering" and the presidents of its members, "European Federation of Chemical Engineering", "Inter-American Confederation for Chemical Engineering" and "Asia Pacific Confederation of Chemical Engineering" together with the president of the "European Society of Biochemical Engineering Sciences", the Congress Chair and the Scientific & Technical Program Chair, is the roadmap for Chemical Engineers to be followed in the next years. It is very important that the declaration focus its attention on the promotion of safety because it reflects by one side the attention that all chemical engineers pay to design safe processes and by other that, it is something that never could be set aside, that never should stop to consider. Despite all efforts made on regulations, best practices and management systems, accidents still occur. Why? May be, because they are as an addition of many small miss functions; or because they are the * Corresponding author.

Improving the performance of internal combustion engines (ICE), together with lowering emissions, are the main targets for specialists in the automotive field. One option for increasing engine efficiency is creating a considerable amount of boost for the inlet combustion air by means of supercharging. In addition to common turbochargers, an alternative solution that has interested researchers for almost a century is the pressure wave supercharger (PWS). This paper is, at first, a complimentary tribute to most of the researchers that studied, experimented with and improved PW supercharging technology from the 50′s to the present. Second, this review emphasizes the performance achieved by ICEs when using PW supercharging, highlighting the limits of these main parameters in different operating conditions, based on the main reported results in the literature. It also provides an overview of PW supercharging technology, with its main advantages and disadvantages and suggests some technic...

The Pressure Wave technology has proved real potential in improving performance and efficiency of thermodynamic systems. Its working principle is based on the transfer of energy between two fluids that are in direct contact for a very short period of time. This technology was implemented in many various applications, including: pressure wave superchargers for internal combustion engines, wave rotor constant volume combustors, novel generation of rotary thermal separators, wave rotor refrigerators, ultra-micro gas turbines, heat exchangers cleaning devices, etc. This paper is a theoretical analysis of the evolution of the pressures along the wave rotor channels for the exhaust gases and for the fresh air. Furthermore, a simulation of the phenomenon at the contact of the two fluids is provided in order to show the interaction of the high energy fluid with the low energy fluid. The theoretical analysis was made using COMSOL Multiphysics software. The study results were represented grap...

Ignitability and the ignition delay time of a combustible mixture in a long combustion chamber, ignited by a hot combustion torch jet generated in a pre-chamber was investigated experimentally in relation to application as a viable igniter method for wave rotor combustors. Methane-air, ethylene-air, and propane-air in varying equivalence ratios were investigated as the combustible mixture in the combustion chamber. The effects of variation in the torch jet fuel, initial equivalence ratio in the pre-chamber, and nozzle geometry on the ignitability and the ignition delay time of combustible mixtures were observed and analyzed. The single-channel wave-rotor combustion rig at Combustion and Propulsion Research Laboratory at the Purdue School of Engineering and Technology at Indiana University-Purdue University, Indianapolis was used for this study. High-speed video imaging techniques to observe the ignition and flame propagation in the combustion chamber and fast-response pressure trans...

Lean manufacturing has fundamentally changed the way business leaders think about the production of manufactured goods and services. Over the past three decades, firms have dedicated considerable resources to reducing production setup times, shrinking inventories, and organizing work into cellular flows. Discrete parts manufacturing has benefited from production planning schemes that smooth production and levelload the plant to reduce idle time and overtime. But in the process industries, where production occurs 24 hours a day, seven days a week, what does it mean to level-load the production facility? In those industries, capacity stabilization is defined as creating production cycles that are predictable, and level-loading consists of stabilizing manufacturing lead times. In this article, we describe the differences between what we call inventory-centric versus capacity-centric modes of production and inventory control, and we present data collected from a large chemical plant ope...

In the process industries, specialized equipment and production processes often necessitate the manufacture of products in a predetermined sequence to minimize changeover time and to simplify scheduling complexity; these types of schedules are referred to as pure rotation schedules, or product wheels, where the circumference of the wheel is the production cycle length. In these industries changeover times between the production of individual products can consume considerable time as well as raw materials and it is therefore often desirable to stabilize the production cycles in order to minimize unplanned changeovers as well as quote accurate lead times to customers. Materials requirements planning (MRP) systems are often used to plan and coordinate production and supply resources with demand in these environments. Central to the effectiveness of the MRP system is the dependability of the lead time parameters. In this paper, we introduce an optimization model to determine safety stock levels that minimize long run expected costs where a stable, cyclic schedule is used. Our model may be used strategically to assess inventory investment requirements as a function of capacity investment, product mix, production technology, demand volatility, and customer service levels. It may be used tactically to optimize item-level planning parameters such as lot size, safety stock and lead time in an MRP system and to support sales and operations planning (S&OP) processes where knowing the future costs associated with current decisions is highly desirable.

Pressure gain combustion (PGC) is widely considered to improve gas turbine thermal efficiency substantially. However, there is no consensus on the modelling in gas turbine performance simulation. Even though it remains the main tool for design studies, the steady-state 0D representation has difficulties in modelling the inherently intermittent behaviour of pressure gain combustion. Selecting the optimal gas turbine design is therefore difficult as common PGC models tend to under-or overestimate performance. In this paper, an algebraic combustor model is inferred from published CFD data and varied to have an optimistic and pessimistic representation. These models among others will be used in an optimisation to identify the best gas turbine design with respect to thermal efficiency. The consideration of the secondary air system and blade metal temperatures ensure a realistic case study. At the end of this paper, sensitivity studies shed light on cycle design at uncertain combustor performance. The selected PGC models achieve an improvement in thermal efficiency between 3.8-6.6 percentage points compared to conventional isobaric combustion. However, this is less than half the 13.3 percentage points gain promised by ideal isochoric combustion.

Within the Collaborative Research Center 1029 new combustion technologies are examined. They might increase the efficiency of modern gas turbines. Especially the Pulsed Detonation Combustion is promissing, though the rising pressure challenges the turbine cooling and hot gas sealing. The current work examines the impact of an unsteady combustion to the turbine sealing cavity, which prevents hot gas ingestion into the inner machine. Sealing flow is ensured by relatively cold secondary air blowing radially through the rotor-stator-wheel space. The interaction between the sealing flow and the main gas flow however causes aerodynamic losses. These losses as well as the secondary compressor air should be kept at a minimum in order to increase the efficiency of the whole engine.

Technical paper by:
Kelvin Fu, Aaron J. Knobloch, Bryan A. Cooley, David C. Walther, Carlos Fernandez-Pello, Dorian Liepmann (University of California, Berkeley),
+ Kenji Miyaska (Fukui University, Japan)

2001, 6 pages

> Content
  » Abstract  1
  » Nomenclature  1
  » Introduction  1
  » Quenching experiments  2
  » Rotary engine design + scaling issues  4
  » Conclusions  6
  » Acknowledgments  6
  » References  6

A research program is currently underway with the purpose of developing a MEMS-sized rotary (Wankel-type) internal combustion micro-engine, which would use liquid hydrocarbon as fuel and would be capable of delivering power on the order of milli-watts. The most significant issue in sustaining combustion in an engine of this size is the increased heat losses due to the high surface-to-volume ratio,

german keywords: Wankelmotor / Kreiskolbenmotor
English Keywords: Wankel Engine / Wankel Rotary Engine / Rotary Piston Engine / Rotary Combustion Engine

The current concerns of mankind on reducing the disastrous effects of global climate warming have led to measures that involve improving the performance of internal combustion engines (ICE). Supercharging is one of the methods of increasing efficiency and thus optimizing ICE’s energy management. The pressure wave superchargers (PWS) proved to be an economic solution with a simple geometry and fast operating response. The researchers’ efforts to develop the pressure wave devices, encountered a rather slow progress during more than a century since the first pressure exchanger was proposed, mainly caused by the meticulous calculation and simulation of the complex phenomena occurring inside the rotor channels. Currently, progress in computerized programs has facilitated modeling and understanding of these processes. Continuous incentives for achieving energy efficiency together with replacing the older technology with new and innovative one have stimulated lately new interest in wave ro...

The precise and accurate measurement of flow rate in the batch flow of the solid particles is of primary importance in many process industries for the improvement of the efficiency of the system. Many techniques developed for the measurement of mass flow rate. The capacitive sensors has a significance of being non-invasive, higher accuracy and low cost for mass flow measurement despite the fact that many factors adversely affect the performance- including non-uniform flow, multiphase flow, temperature, pressure, and moisture in the solid particles. This paper covers preliminary investigations of the offline estimation of mass flow concentration based upon the calibration of capacitance electrodes to quantify the mass of dielectric as a function of capacitance variation between the electrodes.

This paper reports upon recently completed work which designed, assembled, and successfully demonstrated the fundamental operation of a flight-scale Pulse Detonation Engine (PDE) device which incorporated the essential components of a viable airbreathing PDE propulsion system. A prototype flightscale Rotary-Valved Multiple-combustor Pulse Detonation Engine (RVMPDE) was designed, constructed, and successfully operated during an aggressive 18 month effort supported by the US Air Force. This prototype PDE-based propulsion system is a descendant from earlier sub-scale proof-of-concept Rotary-Valved Single-combustor PDE (RVSPDE) and RVMPDE devices (Hinkey et al., 1997) and was intended to demonstrate that a flight-scale RVMPDE could operate at high firing frequencies, produce thrust levels consistent with predictions, operate consistently for a significant duration, and demonstrate the RVMPDE concept of utilizing multiple combustors which are periodically isolated from the inlet manifold via a rotary valve. The prototype RVMPDE device was installed at the Naval Postgraduate School (NFS) Combustion Laboratory and successfully tested over a six month period. Results from the testing program demonstrated that the RVMPDE concept is fundamentally viable as an air breathing propulsion system. Desired thrust levels and combustor cycle rates were demonstrated during engine operations of significant duration. Reliable and consistent detonative combustion of the gaseous hydrocarbon fuel/air mixture was attained under a variety of operating conditions without experiencing pre-ignition of the fuel/air mixture. A variety of thrust levels were achieved during a single experiment demonstrating that the RVMPDE can be easily throttled without suffering a serious degradation in propulsive efficiency.

Conventional gas turbine engines burn fuel in a steady state combustor at constant pressure, and the pressure rise is obtained by the compressor driven by the turbine. In the Pressure Gain Combustion cycle, the combustion process is at constant volume, allowing an increase of the pressure without the need of the compressor. The process is not steady, and some difficulties arise to study it, in particular when one tries to join this unsteady process with a steady system, like a conventional gas turbine engine. In this work some characteristics of PGC system are studied, focusing on the possibility to raise the thermal efficiency of the whole system. Through a numerical program a thermal analysis of the system is performed, computing the main performance and efficiency.

1,2,3,4Student, SRM Institute of Science and Technology, Chennai, India 5Assistant Professor, SRM Institute of Science and Technology, Chennai, India -------------------------------------------------------------------------***-----------------------------------------------------------------------Abstract—Using a pressure wave supercharger (PWS) is an effective way of increasing the performance of the engine. In this paper, based on the specifications of the diesel engine, a pressure wave supercharger is designed suitably to improve the performance of the engine. The analysis of the supercharger has also been carried out to know about the temperature, pressure and velocity characteristics of the supercharger. Based on the results from the analysis, a number of modifications have been designed in this paper which would help increase the effectiveness of the device, when coupled to an engine.

It is a known fact that machined impellers result in improved compressor performance compared to cast impellers of the same design. The performance improvements can be attributed to better surface finish, more accurate geometric definition (tighter dimensional tolerances), well defined edges, and the lack of blade tip fillet on shrouded impellers. In addition, it has been observed through experimental investigations that the construction method of the impellers has an impact on performance. For flank-milled machined impellers, a hub and shroud blade profile is connected by pre-determined straight-line-elements (SLE) - which would correspond to a tool path - to generate the blade surface according to the design intent of the compressor engineer. For cast impellers, the method of connecting hub and shroud blade profile points leads to an arbitrary surface definition and is dependent upon a designer's interpretation of blade profile data and/or the solid model, as well as the CAD s...

The wave rotor (pressure exchanger) is a device working based on a relatively simple idea of operation, but is challenging in its technical realization and difficult to simulate numerically. It has been common practice to create and use specialized codes for simulating the wave rotor operation. The current work presents an attempt of developing 2D and 3D models of radial and axial wave rotors using the commercial software package FLUENT. In this study geometrical models are used for the device casing and rotor cells. The application of carefully chosen initial and boundary conditions enabled the realization of relative motion of the rotor model. The vast information about the unsteady processes occurring during simulation are visualized. It occurs that such type of models are useful for the final test of devices, after the geometry was optimized by the use of specialized but much simpler 1D codes.

Conventional gas turbine engines burn fuel in a steady state combustor at constant pressure, and the pressure rise is obtained by the compressor driven by the turbine. In the Pressure Gain Combustion cycle, the combustion process is at constant volume, allowing an increase of the pressure without the need of the compressor. The process is not steady, and some difficulties arise to study it, in particular when one tries to join this unsteady process with a steady system, like a conventional gas turbine engine. In this work some characteristics of PGC system are studied, focusing on the possibility to raise the thermal efficiency of the whole system. Through a numerical program a thermal analysis of the system is performed, computing the main performance and efficiency.

The main objective of the following paper is to identify and elaborate the parameters that have a significant impact on the operational characteristics of the Pressure Wave Supercharger also known as Comprex. This type of supercharger can transfer some of the ...

Quantification of Risk Reduction Due to the Installation of Different Lightning Protection Solutions for Large Atmospheric Storage Tanks Amos Necci*, Giacomo Antonioni, Valerio Cozzani, Alberto Borghetti, Carlo Alberto Nucci a Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, DICAM, Alma Mater Studiorum Università di Bologna, via Terracini n.28, 40131 Bologna, Italy Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione «Guglielmo Marconi», DEI, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy amos.necci2@unibo.it

We describe how a generic multi-period optimization-based decision support system can be used for strategic and operational planning in a company whose processes can be described in terms of five fundamental elements: Materials, Facilities, Activities, Times and Storage-Areas. We discuss the issues of interface design, data reporting and updating, and production and profit planning. We also compare the performance of two different types of database structure with respect to optimization.

The complete process of iron angles processing; machining and coating by Kalpataru Power Transmission Ltd. has been studied in detail. The different phases of production of the iron/steel angles include automation, CNC machines, Robo arms, overhead cranes and other mechanical equipments. After the straightening, shearing, punching, stamping, heating & bending operations are performed upon the different sections; each set of parts follow a sequence of processes. Once the sections are done with the machining processes, they follow the hot dip galvanization process. Surface Fluxing is the primary stage; followed by Steel Galvanizing and finally dichromate quenching. All the sections are arranged in their respective jigs. These structures or frames are handled by the overhead cranes and dipped in various tubs and lifted from them. Initially, the sections perform hot caustic degreasing followed by Hydrochloric acid pickling. Now these sections are rinsed in water and then soaked in a hot...

The dynamic behavior of a wave rotor topped turboshaft engine is examined using a numerical simulation. The simulation utilizes an explicit, onedimensional, multi-passage, CFD based wave rotor code in combination with an implicit, one-dimensional, component level dynamic engine simulation code. Transient responses to rapid fuel flow rate changes and compressor inlet pressure changes are simulated and compared with those of a similarly sized, untopped, turboshaft engine. Results indicate that the wave rotor topped engine responds in a stable, and rapid manner. Furthermore, during certain transient operations, the wave rotor actually tends to enhance engine stability. In particular, there is no tendency toward surge in the compressor of the wave rotor topped engine during rapid acceleration. In fact, the compressor actually moves slightly away from the surge line during this transient. This behavior is precisely the opposite to that of an untopped engine. The simulation is described. Issues associated with integrating CFD and component level codes are discussed. Results from several transient simulations are presented and discussed.

The reduction of fuel consumption in gas turbines, along with the achievement of high levels of performance, remains one of the main goals of the engine's designer. Addition of a heat exchanger (regenerator) is a common method adopted primarily in ground power units where engine's weight and size is not an issue. Moreover, wave rotor technology has shown very promising results in terms of performance enhancement when applied to gas turbines. In this article, detailed calculations are performed for one and two-shaft regenerated gas turbine engines topped with wave rotors built for industrial applications. Having identified the proper placement of the wave rotor in such engines, thermodynamic cycle analysis is implemented, illustrating performance benefits in terms of specific work and specific fuel consumption,

In this paper, an alternative micro-gas turbine is proposed, where the traditional compressor-turbine arrangement is replaced by an axial, throughflow wave rotor. The investigated wave rotor features symmetrically cambered wall profiles and angled port arrangement for shaft power extraction and uses shock and rarefaction waves for pressure exchange and to achieve gas compression and expansion within a single device. A validated quasi-one-dimensional model that solves the laminar Navier-Stokes equations using a two-step Richtmyer scheme with minmod flux limiter is employed to characterise and examine microgas turbine behaviour. The model accounts for wall heat transfer, flow leakage, wall friction and inviscid blade forces. In addition, modified boundary conditions consider finite passage opening effects and a simple steady-flow combustor model is defined that links the high pressure in-and outlet ports. The model is used to conduct a parametric study to investigate the effects of leakage gap, heat release rate, exhaust backpressure, as well as profile camber on gas turbine performance with a focus on generated combustor compression and expansion efficiency, shaft power and system efficiency. The implications of combustor pressure loss as well as effects of a potential recuperator are discussed as well. The results identify axial leakage and combustor pressure loss as primary drivers for enhanced performance. Finally, the results reinforce the capacity of wave rotors to compress and expand gas efficiently, while thermal efficiency remains below 10 percent. Variables ṁ Mass flow rate [kg/s] Q Rate of heat flow [W] F Flux vector S Source term vector U State vector A Cross-sectional area [m 2 ] a Speed of sound [m/s] C Absolute velocity [m/s] c p Specific heat capacity at const. pressure [J/(kg•K)] c v Specific heat capacity at const. volume [J/(kg•K)] C D Discharge coefficient [-] D Diameter [m] e Specific internal energy [J/kg] f Friction factor [-] H Channel height [m] h Specific enthalpy [J/kg] htc Convective heat transfer coefficient [W/(m 2 •K)]

This paper presents a method of modeling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at the component and engine levels. Using this approach, a performance model of a geared turbofan with a contra-rotating core (CRC) is created. This configuration was investigated in the context of the European program “NEW Aero-Engine Core Concepts” (NEWAC). The core consists of a seven-stage compressor and a two-stage turbine without interstage stat...

Within the Collaborative Research Center 1029 new combustion technologies are examined. They might increase the efficiency of modern gas turbines. Especially the Pulsed Detonation Combustion is promissing, though the rising pressure challenges the turbine cooling and hot gas sealing. The current work examines the impact of an unsteady combustion to the turbine sealing cavity, which prevents hot gas ingestion into the inner machine. Sealing flow is ensured by relatively cold secondary air blowing radially through the rotor-stator-wheel space. The interaction between the sealing flow and the main gas flow however causes aerodynamic losses. These losses as well as the secondary compressor air should be kept at a minimum in order to increase the efficiency of the whole engine. The experiments were carried out at the HotAcoustic-Testrig (HAT) wind tunnel at the TU Berlin. The HAT provides the possibility of steady or unsteady flow conditions, with a controlled high pressure and / or high...

The TDR-helicopter concept is a helicopter configuration with no mechanical transmission, using coaxial rotors driven by a Ljungström turbine. This configuration offers reduced helicopter complexity and weight. Three TDRhelicopter cycles are proposed and examined thermodynamically. The piston engine cycle, using Avgas and diesel, and the turboshaft engine cycle exhibit design cycle specific fuel consumptions that are competitive with conventional helicopters, even though being limited by the Ljungström turbine bearing temperature. However, the turboshaft engine cycle is less attractive because of the need for heat exchangers and the loss of the exhaust gas mass flow. The turbofan cycle does not suffer from this problem and offers the potential to outperform the conventional helicopter, while offering propulsive force in addition.

A parametric investigation has been made of thrust augmentation of a 1 inch diameter pulsed detonation tube by ejectors. A set of ejectors was used which permitted variation of the ejector length, diameter, and nose radius, according to a statistical design ...

In this paper, a dynamic combustor model for inclusion into a one-dimensional full gas turbine engine simulation model, with high numerical accuracy is developed. Effects of dominant parameters, such as frequency and amplitude of the inlet air and fuel mass flow rate fluctuations, on outlet temperature of the combustion chamber, are investigated. The main goal of this research is to analyze the response of the gas turbine combustor to dynamic events that occur in the compressor. In the present work, for modeling combustion, the equations of chemical equilibrium (a second-law concept) are developed and applied to combustion-product mixtures. Thus the heat released from combustion is computed and used as a source term in the energy equation. Ignition effects either would be considered with a time lag equation as a source term in the energy equation. The combustor flammability limits are determined by using available experimental data for various gases and also Le Chatelier’s law. Sour...

Detonation combustion based engines are more efficient compared to conventional deflagration based engines. Pulse detonation engine is the new concept in propulsion technology for future propulsion system. In this contrast, an ejector was used to modify the detonation wave propagation structure in pulse detonation engine combustor. In this paper k-ε turbulence model was used for detonation wave shock pattern simulation in PDE with ejectors at Ansys 14 Fluent platform. The unsteady Euler equation was used to simulate the physics of detonation wave initiation in detonation tube. The computational simulations predicted the detonation wave flow field structure, combustion wave interactions and maximum thrust augmentation in supersonic condition with ejectors at time step of 0.034s. The ejector enhances the detonation wave velocity which reaches up to 2226 m/s in detonation tube at same time step, which is near about C-J velocity. Further the time averaged detonation wave pressure, tempe...

Within the Collaborative Research Center 1029 new combustion technologies are examined. They might increase the efficiency of modern gas turbines. Especially the Pulsed Detonation Combustion is promissing, though the rising pressure challenges the turbine cooling and hot gas sealing. The current work examines the impact of an unsteady combustion to the turbine sealing cavity, which prevents hot gas ingestion into the inner machine. Sealing flow is ensured by relatively cold secondary air blowing radially through the rotor-stator-wheel space. The interaction between the sealing flow and the main gas flow however causes aerodynamic losses. These losses as well as the secondary compressor air should be kept at a minimum in order to increase the efficiency of the whole engine. The experiments were carried out at the HotAcoustic-Testrig (HAT) wind tunnel at the TU Berlin. The HAT provides the possibility of steady or unsteady flow conditions, with a controlled high pressure and / or high...

lor filtering the simulation results in the same manner as the experimental data. Funding for this work was provided by the NASA High-Performance Computing and Communications (HPCC) Program. This report contains preliminary findings, subject to rev _sion as analysis proceed ;.

Analysis of the uncertainty to have engineering solution of gas-dynamic and hydrodynamic problems is based on the comparison the prospective engineering solution with experimental result. ln this paper, the mathematical model to estimate heat t1ux along gas-dynamic channel wall and the solution sequence are shown. Statistical informahon and generalizing experimental characteristics about gas- and hydro-dynamic channels were applied to the mathematical model. As the results, it is possible to draw a conclusion that models of the integrated approach, using the averaged statistical data of generalizing characteristics for a turbulent t1ow, without consideration of the turbulent mechanism (characteristic pulsations), can predict a nominal operating regime for gas-dynamic and hydrodynamic systems. The probable deviation of operating regime for newly designed the gas-dynamic channel can achieve 20% from a regime predicted on a basis l-D or 3-D modelling irrespective of a kind of used models.

Power generation in gas turbines is facing three main challenges today: • Low pollution prescribed by legal requirements. • High efficiency to obtain low operating cost and low CO2 emissions. • High specific power output to obtain low product and installation cost. Unfortunately, some of these requirements are contradictory: high efficiency and specific power force the development towards higher temperatures and pressures which increase NO emissions and intensify the cooling and material strength problems. A breakthrough can be achieved by applying an energy exchanger as a topping stage. Inherent advantages are the self-cooled cell-rotor which can be exposed to much higher gas temperature than a steady-flow turbine and a very short residence time at peak temperature which keeps NO emissions under control. The basic idea has been proposed long time ago. Fundamental research has now led to a new energy exchanger concept. Key issues include symmetric pressure-wave processes, partial suppression of flow separation and fluid mixing, as well as quick afterburning in premixed mode. The concept has been proven in a laboratory-scale engine with very promising results. The application of an energy exchanger as a topping stage onto existing gas turbines would increase the efficiency by 17% (relative) and the power by 25%. Since the temperature level in the turbine remains unchanged, the performance improvement can also be fully utilized in combined cycle applications. This process indicates great potentials for developing advanced gas turbine systems as well as for retrofitting existing ones.

The design and adjustment of modern gas turbine engines significantly rely on the use of numerical research methods. This paper reports a method devised for calculating the thermogasdynamic parameters and characteristics of a turboshaft gas turbine engine. The special feature of a given method is a two-dimensional blade-by-blade description of the compressor in the engine system. Underlying the calculation method is a nonlinear mathematical model that makes it possible to describe the established processes occurring in individual nodes and in the engine in general. To build a mathematical model, a modular principle was chosen, involving the construction of a system of interrelated and coordinated models of nodes and their elements. The approach used in modeling a two-dimensional flow in the compressor makes it possible to estimate by calculation a significant number of parameters that characterize its operation. With the help of the reported method, it is possible to estimate the ef...

Pressure wave machinery constitutes a promising device in a wide variety of applications such as superchargers in automobile engines and topping devices in gas turbines. A very attractive feature is the built-in exhaust gas recirculation which provides a substantial reduction in NO x emissions of the engine. The present work presents a simple numerical model based on shock tube flow, accounting for viscous and thermal losses inside the rotor of the supercharger as well as leakage losses at the extremities of the rotor. It is validated against available experimental data of shock tube flow and on a three-port wave rotor, called a pressure divider. The model is then applied on a configuration suited for automobile engine supercharging. Comparisons with experimental data show that the present method can analyse the basic flow patterns inside the rotor, providing a useful tool for pressure wave supercharger flow predictions.

Este trabajo presenta un analisis preliminar sobre los beneficios de ia implementacion de un rotor de onda en una micro-turbina convencional. Este estudio se enfoca en Ia consecucion de un punto de disefio por medio de calculos termicos para asf lograr una geometrfa adecuada, Ia cual podra ser evaluada por medio de Dinamica de Flujo Computacional CFD para determinar Ia viabilidad de Ia implementacion de este dispositive en un motor con micro-turbina a gas de 30 lb, de empuje. Palabras claves. Termodinamica, camara de combustion, rotor de onda.

We use the first and second laws of thermodynamics to analyze the behavior of an ideal jet engine. Simple analytical expressions for the thermal efficiency, the overall efficiency, and the reduced thrust are derived. We show that the thermal efficiency depends only on the compression ratio r and on the velocity of the aircraft. The other two performance measures depend also on the ratio of the temperature at the turbine to the inlet temperature in the engine, T 3 / T i. An analysis of these expressions shows that it is not possible to choose an optimal set of values of r and T 3 / T i that maximize both the overall efficiency and thrust. We study how irreversibilities in the compressor and the turbine decrease the overall efficiency of jet engines and show that this effect is more pronounced for smaller T 3 / T i .

Pressure wave machinery constitutes promising devices in various engineering propulsion applications such as superchargers in automobile engines and topping devices in gas turbines. This article presents applications of a numerical model for the flow field prediction inside wave rotors. The numerical method used consists of an approximate Roe solver that takes into account viscous and thermal losses inside the rotor as well as leakage losses at the extremities of the rotor. The model is extensively validated and then is applied on configurations suited for automobile engine supercharging and for topping devices for gas turbines. For both cases, satisfactory results are obtained by the comparison of the numerical predictions against experimental data available in the literature. It is concluded that the present method can accurately predict the basic unsteady flow patterns inside the rotor.

Pressure wave machinery constitutes a promising device in a wide variety of applications such as superchargers in automobile engines and topping devices in gas turbines. A very attractive feature is the built-in exhaust gas recirculation which provides a substantial reduction in NO x emissions of the engine. The present work presents a simple numerical model based on shock tube flow, accounting for viscous and thermal losses inside the rotor of the supercharger as well as leakage losses at the extremities of the rotor. It is validated against available experimental data of shock tube flow and on a three-port wave rotor, called a pressure divider. The model is then applied on a configuration suited for automobile engine supercharging. Comparisons with experimental data show that the present method can analyse the basic flow patterns inside the rotor, providing a useful tool for pressure wave supercharger flow predictions.

The Instituto Tecnológico de Aeronáutica (ITA) is an Engineering school maintained by the Air Force Command, Ministry of Defense. The aim of the Turbomachines Department at ITA is the human resources training for design and development of aeronautical and industrial gas turbines, necessary for the Gas Turbine Program of the Departamento de Ciência e Tecnologia Aeroespacial (DCTA). The human resources training is carried out in undergraduate and graduate courses at ITA, where topics in gas turbine and turbomachinery are taught. The gas turbine topic is taught in the undergraduate degree, in Mechanical-Aeronautical Engineering course, and focuses on gas turbines' performance for different configurations (turboshaft, turbojet and turbofan). Lecture notes containing the essential elements of the course are made available for the students, addressing the basic theory of the gas turbines required for the performance study at the design and off-design point. The technological aspects are presented and discussed during detailed studies of the actual cycle. Simple gas turbines and more sophisticated ones are studied, for both aeronautical and industrial application. Performance calculations at design and off-design point of the main engine's components and the cycle are done manually, encouraging students to develop spreadsheets. The theory is complemented with laboratory classes and technical visits, when the practicalities involving gas turbines operation and tests are presented to the students. As an activity laboratory class, the students perform disassembly-assembly of a small industrial gas turbine.

The Technological Institute of Aeronautics (ITA) is a Brazilian engineering school supported by the Command of Aeronautics, Ministry of Defense. The topic Gas Turbines taught at the Mechanical-Aeronautical Engineering undergraduate course is focused in engine performance. Handout containing the course essentials is available to the students. The handout covers the basic gas turbine theory, with emphasis on the design and off-design performance. The technological contents are presented during the detailed real cycles study. Simple gas turbines and the more sophisticated engines for aeronautical and industrial applications are covered. Calculations are supported by in-house developed software. Among such software are the ones for component and engine design and analysis and for flow calculation in blade passages, including multi-stage turbomachines. Theory is complemented with lab classes, when the students are presented to practical aspects involving gas turbine operation. The industrial world is presented to the students during visits to industries. The Gas Turbine undergraduate course is described, with details of the teaching process and the experience within the Turbomachines Department.

We use the first and second laws of thermodynamics to analyze the behavior of an ideal jet engine. Simple analytical expressions for the thermal efficiency, the overall efficiency, and the reduced thrust are derived. We show that the thermal efficiency depends only on the compression ratio r and on the velocity of the aircraft. The other two performance measures depend also on the ratio of the temperature at the turbine to the inlet temperature in the engine, T 3 / T i. An analysis of these expressions shows that it is not possible to choose an optimal set of values of r and T 3 / T i that maximize both the overall efficiency and thrust. We study how irreversibilities in the compressor and the turbine decrease the overall efficiency of jet engines and show that this effect is more pronounced for smaller T 3 / T i .

Pressure gain combustion (PGC) is widely considered to improve gas turbine thermal efficiency substantially. However, there is no consensus on the modelling in gas turbine performance simulation. Even though it remains the main tool for design studies, the steady-state 0D representation has difficulties in modelling the inherently intermittent behaviour of pressure gain combustion. Selecting the optimal gas turbine design is therefore difficult as common PGC models tend to under-or overestimate performance. In this paper, an algebraic combustor model is inferred from published CFD data and varied to have an optimistic and pessimistic representation. These models among others will be used in an optimisation to identify the best gas turbine design with respect to thermal efficiency. The consideration of the secondary air system and blade metal temperatures ensure a realistic case study. At the end of this paper, sensitivity studies shed light on cycle design at uncertain combustor performance. The selected PGC models achieve an improvement in thermal efficiency between 3.8-6.6 percentage points compared to conventional isobaric combustion. However, this is less than half the 13.3 percentage points gain promised by ideal isochoric combustion.

The Technological Institute of Aeronautics (ITA) is a Brazilian engineering school supported by the Command of Aeronautics, Ministry of Defense. The topic Gas Turbines taught at the Mechanical-Aeronautical Engineering undergraduate course is focused in engine performance. Handout containing the course essentials is available to the students. The handout covers the basic gas turbine theory, with emphasis on the design and off-design performance. The technological contents are presented during the detailed real cycles study. Simple gas turbines and the more sophisticated engines for aeronautical and industrial applications are covered. Calculations are supported by in-house developed software. Among such software are the ones for component and engine design and analysis and for flow calculation in blade passages, including multi-stage turbomachines. Theory is complemented with lab classes, when the students are presented to practical aspects involving gas turbine operation. The industrial world is presented to the students during visits to industries. The Gas Turbine undergraduate course is described, with details of the teaching process and the experience within the Turbomachines Department.