Author: Luis Tord Gomis Publisher: ISBN: Category : Languages : en Pages :
Book Description
Film cooling is widely used to protect gas turbine blades and vanes from the extremelly hot gases leaving the combustion chamber. Over the past decades, film cooling on blades, vanes and end-wall has been widely studied. In order to understand and define the process several measurement techniques have been developed. Given that numerical simulations are yet not accurate enough, as they are not able to take into account all the parameters that affect such process, the interest in experimental measurements has grown. Several measurement techniques have been used in order to calculate the film cooling effectiveness and being able to understand how the different variables affect to the overall efficiency of the process. Trying to determine film cooling efectiveness, Pressure Sensitive Paints (PSP) have been recently adapted and used. PSP have been developed since 1980s for different fluid mechanics and aerodynamic testing expermients. Since 1990s the technique is mature enough to be used and achieve high quality results in industrial wind tunnels. PSP is an absolute transducer able to convert units of surface pressure into units of light. PSP systems are able to give high precision measurements with full-surface coberture and high resolution. As PSP is a non-intrusive measurement technique, once it is designed it can be relatively easy adapted to new systems. This Master Thesis focuses on PSP technique, and aims to give a global explanation of the technique as well as a clear and precise definition of each part of the process. The main goal for this project is to design, build and test a PSP system. In order to test the PSP system, a test setup has been design, consisting in a flat test plate with cooling holes. The design of the process has been thought to be tested in the small Wind tunnel owned by the department Gasturbinen, Luft- und Raumfahrtantriebe (GLR) in the Technische Universität am Darmstadt (TUD). Although the long term objective is to adapt such system to other facilites owned by the same department such as the High Reynold Number Turbine (HiReNT) or the Large Scale Turbine Rig (LSTR).
Author: Earl Logan, Jr. Publisher: CRC Press ISBN: 0203911997 Category : Technology & Engineering Languages : en Pages : 927
Book Description
Building on the success of its predecessor, Handbook of Turbomachinery, Second Edition presents new material on advances in fluid mechanics of turbomachinery, high-speed, rotating, and transient experiments, cooling challenges for constantly increasing gas temperatures, advanced experimental heat transfer and cooling effectiveness techniques, and propagation of wake and pressure disturbances. Completely revised and updated, it offers updated chapters on compressor design, rotor dynamics, and hydraulic turbines and features six new chapters on topics such as aerodynamic instability, flutter prediction, blade modeling in steam turbines, multidisciplinary design optimization.
Author: Jacob Ward Harral Publisher: ISBN: Category : Gas-turbine industry Languages : en Pages : 248
Book Description
Abstract: Increasing the efficiency in gas turbine engines requires constant improvement in the design tools currently available to the industry. One area for potential increases in efficiency deals with the film-cooling effectiveness in the high-pressure turbine section of the engine and the push to increase the temperature at the inlet of the turbine. Modeling of film-cooling effectiveness for incorporation into advanced CFD codes to be used for film effectiveness predictions and subsequent design of advanced engines is currently a major activity within the engine community. For the codes to be implemented as design tools one must gain confidence in their validity. One method that has been used for this purpose is to compare predictions obtained using these codes with experimental results obtained under as realistic conditions as is possible within the confines of controlled laboratory experiments. Under support of the NASA/DoD URETI, the OSU GTL has undertaken the task of performing detailed surface-pressure and surface heat-transfer measurements on the vane surfaces, on the blade surfaces, and on the stationary shroud of a fully cooled high-pressure turbine stage operating at design corrected conditions. Several significant changes have been made to the OSU Gas Turbine Laboratory blowdown turbine facility and to the operating mode of that facility in order to make film effectiveness measurements. One of the major facility changes was the incorporation of a coolant gas supply system (LCF) into the facility. The major changes in operating mode involved operating in blowdown mode instead of shock tube mode. In order to achieve this major change in operating procedure, it was necessary to incorporate a resistance heater into the rig just ahead of the high-pressure turbine vane inlet so that a resistance heater instead of the reflected shock could heat the test gas. The next major task was to sequence the main test gas flow with the coolant gas flow so that one could achieve the proper flow physics. This thesis will focus on the operation and integration of the LCF into the blowdown facility and on the experimental results acquired during the initial film-cooling experiment. Operation of the LCF is divided into three distinct areas: fast acting valve operation and sequencing with the main facility fast acting valve, cooling cycles, and facility controls. Successful integration of the LCF has been achieved and will be illustrated by the results of the initial film-cooling experiment. Through these experimental results and accompanying uncertainty analysis conducted as part of this thesis significant knowledge has been gained and will be applied to future film-cooling measurement programs. With the demonstrated successful operation of the OSU turbine test facility in conjunction with the LCF, the OSU GTL is capable of conducting the critical experiments necessary to provide critical verification information for ongoing film effectiveness modeling and CFD code development.
Author: North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development Publisher: ISBN: Category : Aeronautics Languages : en Pages : 614
Author: Emma Veley Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Cooling of the high-pressure turbine in a gas turbine engine is essential for durability because the gas temperature entering the turbine exceeds the melting point of the hardware. Both internal and external cooling reduces the temperature of the blades and vanes. Using air that bypassed the combustor as coolant, the convective heat transfer from the hardware to this internal coolant is often augmented by ribs or a serpentine path. To cool the external surface, coolant passes through holes on the outer wall of airfoil. The coolant creates a protective film on the surface. The shape of the cooling hole influences the cooling effectiveness of this film cooling. Additive manufacturing facilitates rapid prototyping compared to traditional manufacturing methods, which can be exploited for designing and evaluating cooling schemes of gas turbine hardware. The work in this dissertation used additive manufacturing to investigate the cooling performance of several internal and external cooling schemes manufactured in at engine scale for the unique objective of determining the impacts of the internal cooling scheme on the external cooling. A variety of cooling hole shapes were investigated for this work: cylindrical hoes, meter-diffuser shaped holes, and novel optimized holes. Once additively manufactured, the as-built cooling hole surfaces were analyzed to determined their roughness and minimum cross-sectional areas. The arithmetic mean roughness of holes built at the optimal build orientation (perpendicular to the build plate) were on the order of 10 [mu]m; whereas those investigated at other build orientations had roughness values up to 75 [mu]m. For the holes built perpendicular to the substrate the minimum cross-sectional area was usually greater than the design intent but within 15%. The additive process also created an overbuilt lip on the leading edge (windward) side of the hole exit for these holes because of the thin wall thickness in the design. Using these cooling holes, the impact of rounding on meter-diffuser shaped holes and optimized holes on overall effectiveness was investigated. The rounding, which came in the form of inlet fillets on the meter-diffuser shaped holes, was found to decrease the required pressure ratio to obtain the same cooling effectiveness. The deviations from the design due to the additive process caused the novel cooling hole shapes designed through adjoint optimization to perform differently than anticipated. For example, the coolant jet from hole designed for co-flow did not bifurcate as the computational simulation showed. The cross-flow optimized hole outperformed the co-flow optimized hole for most of the tested blowing ratio when both holes were tested in a co-flow configuration. These results from the novel optimized holes proved the necessity of experimentally verifying new designs prior to incorporating into final cooling schemes. The effect of supply channel height, number of channels, ribs, and the cross-sectional shape of the supply channel was investigated to determine the impact of each on the overall effectiveness. Designs that had high overall effectiveness from only internal cooling had less augmentation in effectiveness from film cooling than designs with less effective internal cooling. For example, a ribbed channel typically had a lower film-cooling augmentation than the film-cooling augmentation for same supply channel without ribs. However, a highly effective feed channel can obtain a higher overall effectiveness without any film cooling than a poorly performing feed channel can obtain with film cooling. But the features that create a highly effective feed channel can also cause the cooling jet to lift-off the surface and mix with the hot gas path, which was seen with some rib and hole combinations and with the triangle -- vertex down supply channels. Therefore, the hole shape, the supply channel geometry, and the junction between the two all significantly contribute to a cooling scheme's performance and all three must be considered concurrently to create an optimal cooling design.
Author: Greg Natsui Publisher: ISBN: Category : Languages : en Pages : 320
Book Description
High fidelity measurements are necessary to validate existing and future turbulence models for the purpose of producing the next generation of more efficient gas turbines. The objective of the present study is to conduct several different measurements of multi-row film cooling arrays in order to better understand the physics involved with injection of coolant through multiple rows of discrete holes into a flat plate turbulent boundary layer. Adiabatic effectiveness distributions are measured for several multi-row film cooling geometries. The geometries are designed with two different hole spacings and two different hole types to yield four total geometries. One of the four geometries tested for adiabatic effectiveness was selected for flowfield measurements. The wall and flowfield are studied with several testing techniques. Pressure sensitive paint and discrete gas sampling taps are simultaneously used to measure adiabatic film cooling effectiveness by taking advantage of the heat and mass transfer analogy. All cooling regimes documented by Goldstein (1) for a single row are seen in the multi-row geometries studied. As the blowing ratio increases from 0, the laterally averaged effectiveness increases everywhere, until a point is reached at which upstream rows begin to drop in performance while the downstream rows increase in performance. Finally, a point is reached at which the cooling performance drops everywhere as the blowing ratio is increased.
Author: Randall Paul Williams Publisher: ISBN: Category : Languages : en Pages : 258
Book Description
A scaled-up gas turbine vane model was constructed in such a way to achieve a Biot number (Bi) representative of an actual engine component, and experiments were performed to collect temperature data which may be used to validate computational fluid dynamics (CFD) codes used in the design of gas turbine cooling schemes. The physical model incorporated an internal impingement plate to provide cooling on the inner wall surface, and film cooling over the external surface was provided by a single row of holes located on the suction side of the vane. A single row of holes was chosen to simplify the operating condition and test geometry for the purpose of evaluating CFD predictions. Thermocouples were used to measure internal gas temperatures and internal surface temperatures over a range of coolant flow rates, while infra-red thermography was used to measure external surface temperatures. When Bi is matched to an actual engine component, these measured temperatures may be normalized relative to the coolant temperature and mainstream gas temperature to determine the overall cooling effectiveness, which will be representative of the real engine component. Measurements were made to evaluate the overall effectiveness resulting from internal impingement cooling alone, and then with both internal impingement cooling and external film cooling as the coolant flow rate was increased. As expected, with internal impingement cooling alone, both internal and external wall surfaces became colder as the coolant flow rate was increased. The addition of film cooling further increased the overall effectiveness, particularly at the lower and intermediate flow rates tested, but provided little benefit at the highest flow rates. An optimal jet momentum flux ratio of I=1.69 resulted in a peak overall effectiveness, although the film effectiveness was shown to be low under these conditions. The effect of increasing the coolant-to-mainstream density ratio was evaluated at one coolant flow rate and resulted in higher values of overall cooling effectiveness and normalized internal temperatures, throughout the model. Finally, a 1-dimensional heat transfer analysis was performed (using a resistance analogy) in which overall effectiveness with film cooling was predicted from measurements of film effectiveness and overall effectiveness without film cooling. This analysis tended to over-predict overall effectiveness, at the lowest values of the jet momentum flux ratio, while under-predicting it at the highest values.
Author: Tianshu Liu Publisher: Springer Science & Business Media ISBN: 3540266445 Category : Technology & Engineering Languages : en Pages : 331
Book Description
Luminescent molecule sensors, called pressure-sensitive paint (PSP) and temperature-sensitive paint (TSP), measure factors essential for understanding the aerodynamic performance and heat transfer characteristics of flight vehicles. They provide a powerful tool for experimental aerodynamicists to obtain a deeper understanding of the rich physical phenomena in complex flows around a flight vehicle. This book helps the reader to understand the physics and chemistry and the capabilities of PSP and TSP. It provides an overview of the wide scope of applications and explains the system requirements for using these sensors. The book also includes an extensive table of properties of PTP and TSP. As such, it is a thorough and up-to-date coverage of the underlying physics and applications of luminescent molecules designed for global pressure and temperature mapping
Author: Luis Tord Gomis
Author: Earl Logan, Jr.
Author: Jacob Ward Harral
Author: North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development
Author: Emma Veley
Author: Greg Natsui
Author: 
Author: Randall Paul Williams
Author: Tianshu Liu
Author: