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Viewing 1 to 30 of 979
2014-09-16
Technical Paper
2014-01-2133
Darcy Allison, Edward Alyanak
Abstract For the design process of the class of aircraft known as an efficient supersonic air vehicle, particular attention must be paid to the propulsion system design as a whole including installation effects integrated into a vehicle performance model. The propulsion system assumed for the efficient supersonic air vehicle considered in this paper is a three-stream variable cycle engine. A computational model has been built with the Numerical Propulsion System Simulation (NPSS) software to analyze this engine. This engine model was based on the generic adaptive turbine engine model developed at the turbine engines division of the US Air Force Research Laboratory. Along with this variable cycle NPSS model, a three-ramp external compression inlet model meant for conceptual design has been developed. This model will be used to capture inlet installation effects, including those attributable to angle of attack changes at supersonic Mach numbers. These models have been integrated into the Service ORiented Computing EnviRonment (SORCER), which enables parallel execution of the installed NPSS model to rapidly evaluate a full flight envelope.
2014-09-16
Technical Paper
2014-01-2230
Ruiqiang Lu
Abstract With the development of many new technologies in aircraft manufacturing area and the increasing competition of the global market, aircraft manufacturing enterprises have to reduce their production time and increase the cost-efficiency, with the consideration of high speed response to the changes inside enterprises or in the environment. Production scheduling is a significant process in manufacturing, especially for complicated part or component processing. This paper proposes an agent based multi-objective optimization approach for production scheduling based on Genetic Algorithms. It aims to minimize the total production cost and simultaneously reducing the emission released during production, and the delivery time and equipment constraints are satisfied as well. The new approach is tested in a virtual plant for turbine blade manufacturing. Experimental results show that a group of Pareto optimal solutions are obtained, which can be provided to the decision maker of the manufacturer to select according to different actual conditions.
2014-09-16
Technical Paper
2014-01-2141
Christine Ross, Michael Armstrong, Mark Blackwelder, Catherine Jones, Patrick Norman, Steven Fletcher
Abstract The Turboelectric Distributed Propulsion (TeDP) concept uses gas turbine engines as prime movers for generators whose electrical power is used to drive motors and propulsors. For this NASA N3-X study, the motors, generators, and DC transmission lines are superconducting, and the power electronics and circuit breakers are cryogenic to maximize efficiency and increase power density of all associated components. Some of the protection challenges of a superconducting DC network are discussed such as low natural damping, superconducting and quenched states, and fast fault response time. For a given TeDP electrical system architecture with fixed power ratings, solid-state circuit breakers combined with superconducting fault-current limiters are examined with current-source control to limit and interrupt the fault current. To estimate the protection system weight and losses, scalable models of cryogenic bidirectional current-source converters, cryogenic bidirectional IGBT solid-state circuit breakers (CBs), and resistive-type superconducting fault current limiters (SFCLs) are developed to assess how the weight and losses of these components vary as a function of nominal voltage and current and fault current ratings.
2014-06-30
Technical Paper
2014-01-2066
Ennes Sarradj, Thomas Geyer, Christoph Jobusch, Sebastian Kießling, Alexander Neefe
Abstract The development of energy-efficient and lightweight vehicles is a major challenge for researchers and engineers in the automotive industry, with one solution being the use of micro gas turbines in serial hybrid vehicles. Among other advantages, the use of a micro gas turbine instead of a reciprocating engine enables a high reliability and low emissions. What makes the concept of using a gas turbine even more interesting are its special NVH characteristics, which are quite different from those of a reciprocating engine. Besides the fact that a gas turbine in general produces less noise and vibration than a diesel engine of the same power, the characteristic noise spectrum is also very different. In this paper, the noise characteristics of a micro gas turbine are compared to those typical for a common reciprocating engine and the sources of the noise are considered. The data that form the basis for these analyses were obtained using measurements on a 70 kW micro gas turbine that is designed to be used in a serial hybrid concept for buses.
2014-04-01
Technical Paper
2014-01-1873
Andrew Haughton, Andy Dickinson
Abstract This paper describes the design and development steps taken to realise a functioning Turbo-generator Integrated Gas Energy Recovery System (TIGERS®). The main areas covered focus on simulation, machine design, control system development and validation. The mechanical design for this application is particularly challenging for a number of reasons. The turbine is capable of rotating the shaft at speeds greater than its critical rotating limit. Rolling element grease filled bearings are used to allow application flexibility; these have an operating temperature limit of 200°C. The exhaust gas can reach temperatures greater than 900°C in spark ignition applications, whereas the turbine upper functional limit is 850°C. The power electronics are integrally mounted in the machine and have a maximum thermal operating limit of 120°C. Considering that TIGERS is expected to harvest energy from the exhaust gas it is essential that it not only survives in this harsh environment, but it must also produce work with no adverse impact on vehicle performance or fuel efficiency.
2013-12-20
Technical Paper
2013-01-9004
Matthew Spencer, Timothy Shepherd, Richard Greenwood, Mark Simmons
In the development of a more accurate laboratory scale method, the ability to replicate the thermal oxidative degradation mechanisms seen in gas turbine lubricants, is an essential requirement. This work describes an investigation into the influence of key reaction parameters and the equipment set up upon extent and mechanism of oil degradation. The air flow rate through the equipment was found to be critical to both degradation rate and extent of volatilization loss from the system. As these volatile species can participate in further reactions, it is important that the extent to which they are allowed to leave the test system is matched, where possible, to the conditions in the gas turbine. The presence of metal specimens was shown to have a small influence on the rate of degradation of the lubricant. Loss of metal from the copper and silver specimens due to the mild corrosive effect of the lubricant was seen. The Total Acid Number and viscosity of a series of oil samples from two service gas turbines are discussed.
2013-09-17
Technical Paper
2013-01-2187
Greg Kilchenstein, F. Matthew Juarez, Matthew Moseley, Jonathan Cheverie, Marcio Duffles, Jonathan Acker
Small media ingestion has been known to cause erosion and result in corrosion to compressor components of gas turbine engines. Compressor degradation negatively impacts fuel consumption, engine performance, reliability, and maintenance costs. Power losses in the compressor section are often unrecoverable without increasing fuel consumption; therefore, protecting the compressor from excessive erosion/corrosion may extend the life of an engine, and reduce fuel, maintenance costs, and emissions. A study was conducted to investigate the effect of a new compressor blade and vane erosion/corrosion resistant coating on two Rolls-Royce T56-A7-B engines. The study included a comprehensive sand ingestion test that compared the performance and hardware condition of uncoated and coated compressor airfoils before, during, and after sand ingestion of 135 pounds of sand mixture. As part of the objective, the benefits of a new erosion/corrosion resistant compressor airfoil coating were quantified in regards to fuel efficiency, engine-time-on-wing (ETOW), emissions, fuel costs, maintenance, and engine readiness.
2013-09-17
Technical Paper
2013-01-2130
Edwin Corporan, Matthew DeWitt, Christopher Klingshirn
Measurement of turbine engine particulate matter (PM) requires diligent handling of the sample to maintain integrity and minimize any alteration due to sampling or transport artifacts. PM sample dilution at the probe tip is a common and widely used technique to condition the sample in order to reduce PM losses and potentially “freeze” chemical reactions that may occur throughout the sampling train to the instruments. Diluting the PM sample at a location downstream in the sample line is preferred by engine manufacturers as probes used for gas emissions can be used for PM; however, implications on PM characteristics and comparisons against probe-tip dilution are unknown. The present study compares the characteristics of turbine engine PM diluted at the probe tip and at a location downstream in the sampling train. Downstream dilution was accomplished by injecting nitrogen through a commercial ejector (operated both as a diluter and pump) and a through simple concentric tube arrangement. The tests were conducted using the exhaust of a T63 turboshaft engine as the source of PM.
2013-09-17
Technical Paper
2013-01-2120
Patrick Morelle, norbert kill, Flavio d'Ambrosio
The paper presents first a description of the methods used for the analysis of global dynamics of rotating systems like jet engines but also auxiliary power units. Different methodologies are described so to model rotating parts using beam, but also Fourier multi-harmonic, three dimensional models or to take into account cyclic symmetry and multistage cyclic symmetry concepts. Advantages and disadvantages of the different model types are discussed and compared. The coupling of the rotating parts with casings and stators is then discussed both in the inertial frame and in the rotating frame. The effect on global dynamics of bearing and other linking devices is taken into account for different type of analysis from critical speed analysis, to harmonic and transient analysis. The effect of gears and gear boxes coupling different rotors (like it is the case for auxiliary power units in a jet engine) is then discussed and appropriate methods described so to model this coupling effect. Finally, the question of the simulation of bearings with clearances is discussed and a new formulation proposed for the harmonic analysis of such situation.
2013-09-17
Technical Paper
2013-01-2145
Jonathan L. Geisheimer, David Kwapisz, Thomas Holst, Michael Hafner
Blade tip clearance is a key design parameter for gas turbine designers. This parameter is often measured during engine testing and development phases as part of design validation but has yet to be utilized during normal engine fleet operation. Although blade tip clearance measurements are often mentioned for fleet operation in the context of active clearance control, the use of blade tip clearance measurements can provide an additional benefit for engine health monitoring. This paper explores the use of blade tip clearance sensors for engine condition monitoring of hot section blades. Blade tip clearance, especially in the first stage turbine, has an impact on exhaust gas temperature. The use of tip clearance measurements can provide supplementary information to traditional EGT measurements by providing a direct measurement of wear on the blade tips. In addition, blade creep and cracking can be measured and tracked if the sensors are able to provide clearance values of individual blades.
2012-10-22
Technical Paper
2012-01-2168
Rebekah Lee Puterbaugh, Jeffrey Brown, Ryan Battelle
Recent turbine engine numerical modeling developments have significantly improved the capability to accomplish integrated system-level analyses of aircraft thermal, power, propulsion, and vehicle systems. Combining desired aircraft performance with thermal management challenges of modern aircraft, which include increased heat loads from components such as avionics and more-electric accessories, as well as maintaining engine components at specified operating temperatures, demands we look for solutions that maximize heat sink capacity while minimizing adverse impacts on engine and aircraft performance. Development of optimized aircraft thermal management architectures requires the capability to directly analyze the impact of thermal management components, such as heat exchangers, on engine performance. This paper presents a process to evaluate the impact of heat exchanger design and performance characteristics (e.g., volume and pressure drops) on engine performance. As we are only concerned with sensitivity to the presence of heat exchangers, there has been no effort to optimize the heat exchanger design or the turbine engine flows to improve thermal or engine performance.
2012-10-22
Technical Paper
2012-01-2096
Chris Hickenbottom, Kyusung Kim, Onder Uluyol
This paper discusses recent improvements made by Honeywell's Condition-Based Maintenance (CBM) Center of Excellence (COE) to Mechanical Health Management (MHM) algorithms. The Honeywell approach fuses Condition Indicators (CIs) from vibration monitoring and oil debris monitoring. This paper focuses on using MHM algorithms for monitoring gas turbine engines. First an overview is given that explains the general MHM approach, and then specific examples of how the algorithms are being refined are presented. One of the improvements discussed involves how to detect a fault earlier in the fault progression, while continuing to avoid false alarms. The second improvement discussed is how to make end of life thresholds more robust: rather than relying solely on the cumulative mass of oil debris, the end of life indication is supplemented with indicators that consider the rate of debris generation. Another improvement discussed is an approach for allowing rapid modifications to the logic that fuses vibration and oil debris indicators.
2012-10-22
Technical Paper
2012-01-2095
Kirby J. Keller, Jeanne Maggiore, Robab Safa-Bakhsh, William Rhoden, Michael Walz
The Sensory Prognostics and Management Systems (SPMS) program sponsored by the Federal Aviation Administration and Boeing developed and evaluated designs to integrate advanced diagnostic and prognostic (i.e., Integrated Vehicle Health Management (IVHM) or Health Management (HM)) capabilities onto commercial airplanes. The objective of the program was to propose an advanced HM system appropriate for legacy and new aircraft and examine the technical requirements and their ramifications on the current infrastructure and regulatory guidance. The program approach was to determine the attractive and feasible HM applications, the technologies that are required to cost effectively implement these applications, the technical and certification challenges, and the system level and business consequences of such a system. The scope of the SPMS program included consideration of data collection and communication from the continuous monitoring of aircraft systems, observation of current system states, and processing of this data to support proper maintenance and repair actions.
2012-10-22
Technical Paper
2012-01-2155
Bernard L. Koff
The remarkable evolution of the gas turbine engine has made the world much smaller and provided power for worldwide use. I often think of growing up in a farm environment, being fascinated with machinery and then having the opportunity to take part in the design and development of the world's most complex product. I worked with brilliant engineers and experienced the transition from slide rules and “hand calculation” methods to computers and more precise finite element modeling. Perhaps this story will present insight for current and future design engineers who create the manufactured products used by mankind.
2012-10-20
Technical Paper
2012-01-2245
Mohammad Ahmadi Bidakhvidi, Dean Vucinic, Steve Vanlanduit
The flapping flight is advantageous for its superior maneuverability and much more aerodynamically efficiency for the small size UAV when compared to the conventional steady-state aerodynamics solution. Especially, it is appropriate for the Micro-air-vehicle (MAV) propulsion system, where the flapping wings can generate the required thrust. This paper investigated such solution, based on the piezoelectric patches, which are attached to the flexible plates, in combination with an appropriate amplification mechanisms. The numerical and experimental flow analyses have been carried out for the piezoelectric flapping plate, in order to characterize the fluid structure interaction induced by the swinging movement of the oscillating plate. The time-resolved Particle Image Velocimetry (PIV) measurements were conducted on a piezoelectric flapping wing with finite span operating at 84.8 Hz in air in order to validate the numerical simulations, and the comparison showed good matching, as reported in this paper.
2011-10-18
Technical Paper
2011-01-2511
Douglas F R Silva, Joao Barbosa, Alberto Adade Filho
The current pressure for fuel burn savings and increasing performance in the commercial aerospace market demands highly complex engine control systems to optimize fuel consumption throughout the engine operating envelope, as well as meet the regulatory requirements in terms of safety and performance. These conflicting objectives normally lead to trade-off solutions that are difficult to precisely estimate. Therefore some decisions to characterize the engine controller still reside on experience from previous designs and, as a result, add subjectivity and increase the potential for wrong parameter selection. This paper proposes an algorithmic approach to design a turbojet engine controller in a multivariable, two-degree-of-freedom configuration, obtaining H-infinity robust stabilization. It introduces an optimized loop shaping design procedure, with the use of a Genetic Algorithm (GA), to further improve the control system performance, as well as bring the experience applied by controller designers and engineers to an automated process, when setting the parameters to shape the frequency response of the engine control loops.
2011-10-18
Technical Paper
2011-01-2496
Bhupendra Khandelwal, Liu Bao, Karamveer Singh Kumar, Vishal Sethi, Riti Singh
Significant development in the gas turbine technology has brought about an increase in the performance requirements for modern engines. This has generated a significant interest in researching into implementation of novel technologies for various engine components, which will allow for the design of engines to match the new performance requirements. One such technology is the use of hybrid diffusers in gas turbine combustors against conventional combustors like dump diffusers. The hybrid diffuser concept has been around for a while and has the potential of giving a greater performance than conventional diffusers. However, due to limited information available in the public domain, not much has been fully understood about the mechanism of the hybrid diffuser concept. Much of the previous work done on hybrid diffusers are done on designs having a vortex chamber bleed, based on the belief that vortex chambers helps to stabilize the flow separation. However, this paper takes looks into the proposition that the primary mechanism of a hybrid diffuser is the air bleed rather than the vortex chamber itself.
2011-06-13
Technical Paper
2011-38-0026
Ryan D. May, Ten-Huei Guo, Joseph P. Veres, Philip C. E. Jorgenson
Ice buildup in the compressor section of a commercial aircraft gas turbine engine can cause a number of engine failures. One of these failure modes is known as engine rollback: an uncommanded decrease in thrust accompanied by a decrease in fan speed and an increase in turbine temperature. This paper describes the development of a model which simulates the system level impact of engine icing using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). When an ice blockage is added to C-MAPSS40k, the control system responds in a manner similar to that of an actual engine, and, in cases with severe blockage, an engine rollback is observed. Using this capability to simulate engine rollback, a proof-of-concept detection scheme is developed and tested using only typical engine sensors. This paper concludes that the engine control system's limit protection is the proximate cause of iced engine rollback and that the controller can detect the buildup of ice particles in the compressor section.
2011-06-13
Technical Paper
2011-38-0017
Harold E. Addy, Jr., Joseph P. Veres
Ice accretions that have formed inside gas turbine engines as a result of flight in clouds of high concentrations of ice crystals in the atmosphere have recently been identified as an aviation safety hazard. NASA's Aviation Safety Program (AvSP) has made plans to conduct research in this area to address the hazard. This paper gives an overview of NASA's engine ice-crystal icing research project plans. Included are the rationale, approach, and details of various aspects of NASA's research.
2011-06-13
Technical Paper
2011-38-0080
Chuck Califf, Anabel Rodriguez, Eduardo Lemini, Chiong Tan
The study of Supercooled Large Droplets (SLD) has received greater attention in the Aviation industry since the ATR-72 accident in 1994, which was attributed to SLD. This type of icing cloud usually consists of droplets of up to a millimeter in diameter and mean volumetric diameter (MVD) greater than 40 microns1. The analyses of the ice accretion process with SLD have focused mainly on the wing and stabilizers, particularly on the leading edges where accretion can occur beyond the ice protected areas. There are several numerical and empirical models to predict the mass and shapes of ice accreted from SLD, but there are few published papers that focus on SLD accretion within aircraft turbofan engines2, 3, 4, 5, 6, 7, 8, 9. SLD droplets have higher inertia than conventional icing droplets, which leads to their trajectories being less influenced by the aerodynamic forces. However, large droplets are more likely to breakup than smaller droplets when subjected to highly shear flows. In addition, SLD tends to splash on impact resulting in smaller droplets in the process.
2011-06-13
Technical Paper
2011-38-0099
James MacLeod, John Jastremski
The Global Aerospace Centre for Icing and Environmental Research (GLACIER) facility has been constructed in Thompson, Manitoba, Canada. This project involves the construction and operation of a facility which will provide icing certification tests for large gas turbine engines, as well as performance, endurance and other gas turbine engine qualification testing. MDS Aero Support, in partnership with the National Research Council of Canada (NRC), Pratt and Whitney Canada, and Rolls Royce Canada, has developed a globally unique outdoor engine test and certification facility. The prime purpose of this facility is for icing certification of aviation gas turbine engines, initially for Rolls-Royce and Pratt & Whitney, two of the three largest gas turbine manufacturers in the world. The facility will provide the aviation industry with the required environmental conditions (by virtue of its location), and capability to meet the growing demands for icing certifications and other adverse cold weather conditions.
2011-04-12
Technical Paper
2011-01-1146
Jan Macek, Oldrich Vitek, Zdenek Zak
The physical 1-D model of a radial turbine consists in a set of gas ducts featuring total pressure and/or temperature changes and losses. This model has been developed using the basic modules of generalized 1-D manifold solver. The tools for it were presented at SAE 2008 and 2009 World Congresses. The model published before is amended by a semi-empiric mechanical loss and windage loss modules. The instantaneous power of a turbine is integrated along the rotating impeller channel using Euler turbine theorem, which respects the local unsteadiness of mass flow rate along the channel. The main aim of the current contribution is to demonstrate the use of measured turbine maps for calibration of unsteady turbine model for different lay-outs of turbine blade cascades. It is important for VG turbines for the optimal matching to different engine speeds and loads requirements. The turbine model calibration parameters (flow direction angles, loss coefficients, leakage coefficients) are identified by means of the same model applied to a steady flow turbocharger testbed simulation using optimization to find the best fit.
2009-11-10
Technical Paper
2009-01-3227
Melih Cemal Kushan, Zhongxiao Peng, Shuzhi Peng
This paper presents the study of a defect warning and control system. The developed system has the following functions: (a) detect possible defects in advance by controlling gas turbine compressors (GTC), (b) warn the user, and (c) ensure necessary intervention to prevent the defect from happening or growing is made. The defect warning and control system is a product with a predicting maintenance approach. It measures the vibration, oil pressure, exhaust exit heat and engine speed parameters via sensors during the performance of the gas turbine compressors. It also monitors the action and warns the user in case of danger. If the evaluated parameters reach critical values which may cause a defect, the system detects this in advance and prevents unexpected defects. The application of this system has verified and demonstrated that its designed functions have been achieved successfully.
2008-11-11
Technical Paper
2008-01-2874
Vern E. Brooks
2008-11-11
Technical Paper
2008-01-2929
P. Gemin, M. Shah, R. Raju, K. Sivasubramaniam, S. Galioto, R. Zhou, K. Joerger
Pairing of a high-speed, high-temperature superconducting, homopolar inductor alternator (HTSHIA) with a gas turbine engine as prime mover results in a power dense generator-set well suited to applications requiring large step load accepts and rejects. Though the HTSHIA's low synchronous reactance allows it to respond to large step loads, typical gas turbine engines require seconds to ramp from idle to full power. A mismatch between load and turbine power during a step transient will result in generator speed droop. If the speed droops too severely either the generator or gas turbine engine may no longer be able to maintain rated power. This paper presents a generator set and control approach which exploits the HTSHIA's flywheel properties (high speed and relatively high rotor inertia) to power large, repeated step loads. The gas turbine engine, generator, power conditioning system (PCS), load, and control were modeled to evaluate the system performance, develop control, and to allow system level trades to be made.
2008-09-16
Technical Paper
2008-01-2305
P. Webb, N. Jayaweera, C. Ye, C. Johnson
Transport is a significant contributor to global Carbon Dioxide and Nitrogen Oxide emissions. The VITAL (Environmentally Friendly Aero Engine) project is an integrated project funded under the European Union Sixth Framework programme that aims to design, manufacture and test the critical technologies required to produce cleaner low noise aero-engines. In particular, it should develop innovative technical solutions to reduce the engine's weight, thereby reducing fuel consumption and hence Carbon Dioxide emission. Prime candidates for weight reduction are the engine casings and structures. One way of achieving this is to move from a casting based manufacturing method to a fabrication method. The use of fabrications for these types of structures is not new and was indeed the standard methodology for older engine types. It was however abandoned in favour of castings due to the high costs associated with the complex fixtures required and the significant manual labour input needed. It is proposed that the use of fabrication could become viable again if a much more automated approach was adopted.
2008-06-23
Technical Paper
2008-01-1617
R. Shyam Prasad, Helen T. Ryan, Steven Dell, Don D. Pheneger, Roger M. Sheets
Deposit formation is an issue of great significance in a broad range of applications where lubricants are exposed to high temperatures. Lube varnish causes valve-sticking, bearing failure and filter blockage which can lead to considerable equipment downtime and high maintenance costs. Recently this has become a pressing issue in the stationary power generation industry. In order to investigate the chemistry leading to varnish, three samples of varnish-coated components from the lube/hydraulic systems of gas turbines from the field were obtained, along with information on the commercially available formulated oils which were used. Samples of these three fresh oils were analysed by a variety of chromatographic and spectroscopic techniques, which confirmed chemical identity of aminic and/or phenolic antioxidants, corrosion inhibitors and antiwear components. The varnish-coated turbine components were also investigated by these methods. Notably, several lube additives present in the mother oil or their corresponding decomposition products were found in the varnish, in addition to base oil oxidative degradation products.
2007-09-17
Technical Paper
2007-01-3861
Richard C. Millar, Thomas Mazzuchi, Shahram Sarkani
An extensive reliability and maintenance data base has been compiled for a gas turbine engine used for propulsion of a fleet of military aircraft, covering a full eight years of operational service. Non-parametric statistical tools were applied to analyze the engine flight line removal data set contained in this data base. This analysis was directed towards eliciting information useful in managing maintenance and design change activity directed to enhancing aircraft reliability and availability. Intensive preventive maintenance, high levels of “censoring” due to the phased buildup of the fleet of aircraft and the modular maintenance policy applied to this military engine introduced significant conceptual and practical challenges that required innovations in data treatment and analysis. The resultant analysis toolset is defined and some results described. The results show the tools' utility and suitability for the purpose intended, the visualization and quantification of the hazard function for classes of unplanned engine removals in the context of intensive preventive maintenance.
2007-04-16
Technical Paper
2007-01-0916
V. Ganesan
A gas turbine combustion system is an embodiment of all complexities that engineering equipment can have. The flow is three dimensional, swirling, turbulent, two phase and reacting. The design and development of combustors, until recent past, was an art than science. If one takes the route of development through experiments, it is quite time consuming and costly. Compared to the other two components viz., compressor and turbine, the combustion system is not yet completely amenable to mathematical analysis. A gas turbine combustor is both geometrically and fluid dynamically quite complex. The major challenge a combustion engineer faces is the space constraint. As the combustion chamber is sandwiched between compressor and turbine there is a limitation on the available space. The critical design aspect is in facing the aerodynamic challenges with minimum pressure drop. Accurate mathematical analysis of such a system is next to impossible. However, because of the advent of fast digital computers now a days it has become possible to model both geometrical and fluid dynamics aspects of a combustor using computers.
2007-01-23
Technical Paper
2007-01-0010
Mikiya Araki, Tsuneaki Ishima, Tomio Obokata, Masaaki Arai, Koji Okamoto
Velocity measurement of an intermittent high-speed flow inside a micro wave rotor cell was carried out using a laser Doppler anemometry (LDA). The cell is 3 × 3 mm rectangular tube, whose length is 42 mm. The pressure ratio and rotor speed of the wave rotor were set at 2.5 and 5,000 rpm, respectively. Ethanol droplets were seeded into the flow as scattering particles. By use of laser beam expanders, the probe volume of the LDA optics was minimized, and sub-millimeter special resolution is realized while a wide velocity range (-100 to 300 m/s) is kept. It is shown that the velocity histories at local positions inside the wave rotor cell can be obtained with the LDA optics. The rapid velocity increase and decrease, due to the primary and secondary shock waves, are observed, and the propagation speed of the shock waves was estimated. It is shown that the velocity profile inside the cell is flat and that the boundary layer thickness inside the cell is smaller than 0.5 mm. It is shown that the effect of viscosity is relatively small in such a micro wave rotor.
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