Towards Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

2019 ◽  
Author(s):  
Nishan Jain ◽  
Luis Bravo ◽  
Dokyun Kim ◽  
Muthuvel Murugan ◽  
Anindya Ghoshal ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Variable Speed ◽  
Solution Quality ◽  
Engine Operation ◽  
Turbine Engine ◽  
Design Point ◽  
Large Eddy ◽  
Flow Through

Abstract In this work, massively parallel wall-modeled Large Eddy Simulations (LES) are conducted to simulate flow through a single stage power turbine sector of a gas-turbine engine under realistic operating conditions. The numerical framework in the current work uses finite volume based compressible CharLES solver that utilizes a moving Voronoi diagram based grid generation. To test grid sensitivity and evaluate the capability of the solver in predicting turbomachinery flows, three grids of varying resolution are used to simulate flow through the baseline gas-turbine under design operating conditions. After assessing the flow solution quality and establishing simulation parameters, LES simulations are conducted to investigate the performance of gas-turbine at off-design conditions. The conditions include the rotor design point at 100% speed, and off-design points at 75%, and 50% speeds subject to high temperatures from the combustor exit flow. The results showed that the internal flow becomes highly unsteady as the rotational speed of rotor deviates from the design point leading to reduced aerodynamic performance. This study demonstrates that the current framework is able to robustly simulate the unsteady flow in a three-dimensional moving rotor environment towards the design of variable speed gas-turbine engines for US Army Future Vertical Lift program.

Cycle Design Exploration Using Multi-Design Point Approach

2012 ◽  
Author(s):  
Jeffrey Schutte ◽  
Jimmy Tai ◽  
Jonathan Sands ◽  
Dimitri Mavris
Keyword(s):  
Gas Turbine ◽  
Design Space ◽  
Traditional Approach ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Feasible Region ◽  
Turbine Engine ◽  
Design Point ◽  
Performance Requirements ◽  
Design Cycle

The focus of this study is to compare the aerothermodynamic cycle design space of a gas turbine engine generated using two on-design approaches. The traditional approach uses a single design point (SDP) for on-design cycle analysis, where off-design cycle analysis must be performed at other operating conditions of interest. A multi-design point (MDP) method performs on-design cycle analysis at all operating conditions where performance requirements are specified. Effects on the topography of the cycle design space as well as the feasibility of the space are examined. The impacts that performance requirements and cycle assumptions have on the bounds and topography of the feasible space are investigated. The deficiencies of a SDP method in determining an optimum gas turbine engine will be shown for a given set of requirements. Analysis will demonstrate that the MDP method, unlike the SDP method, always obtains a properly sized engine for a set of given requirements and cycle design variables, resulting in an increased feasible region of the aerothermodynamic cycle design space from which the optimum performance engine can be obtained.

Optimal State-Space Control of a Gas Turbine Engine

1992 ◽  
Vol 114 (4) ◽  
pp. 763-767 ◽  
Author(s):  
J. W. Watts ◽  
T. E. Dwan ◽  
C. G. Brockus
Keyword(s):  
State Space ◽  
Gas Turbine ◽  
State Space Model ◽  
Gas Turbine Engine ◽  
The State ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Analog Control ◽  
Linear State ◽  
High Level

An analog fuel control for a gas turbine engine was compared with several state-space derived fuel controls. A single-spool, simple cycle gas turbine engine was modeled using ACSL (high level simulation language based on FORTRAN). The model included an analog fuel control representative of existing commercial fuel controls. The ACSL model was stripped of nonessential states to produce an eight-state linear state-space model of the engine. The A, B, and C matrices, derived from rated operating conditions, were used to obtain feedback control gains by the following methods: (1) state feedback; (2) LQR theory; (3) Bellman method; and (4) polygonal search. An off-load transient followed by an on-load transient was run for each of these fuel controls. The transient curves obtained were used to compare the state-space fuel controls with the analog fuel control. The state-space fuel controls did better than the analog control.

Design and Analysis of a High Pressure Turbine Using Computational Methods for Small Gas Turbine Application

2013 ◽  
Author(s):  
Kishor Kumar ◽  
R. Prathapanayaka ◽  
S. V. Ramana Murthy ◽  
S. Kishore Kumar ◽  
T. M. Ajay Krishna
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Computational Methods ◽  
Gas Turbine Engine ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Convergence Criterion ◽  
Turbine Engine ◽  
Design Point ◽  
Ansys Cfx

This paper describes the aerodynamic design and analysis of a high-pressure, single-stage axial flow turbine suitable for small gas turbine engine application using computational methods. The specifications of turbine were based on the need of a typical high-pressure compressor and geometric restrictions of small gas turbine engine. Baseline design parameters such as flow coefficient, stage loading coefficient are close to 0.23 and 1.22 respectively with maximum flow expansion in the NGV rows. In the preliminary design mode, the meanline approach is used to generate the turbine flow path and the design point performance is achieved by considering three blade sections at hub, mean and tip using the AMDC+KO+MK+BSM loss models to meet the design constraints. An average exit swirl angle of less than 5 degrees is achieved leading to minimum losses in the stage. Also, NGV and rotor blade numbers were chosen based on the optimum blade solidity. Blade profile is redesigned using the results from blade-to-blade analysis and through-flow analysis based on an enhanced Dawes BTOB3D flow solver. Using PbCFD (Pushbutton CFD) and commercially available CFD software ANSYS-CFX, aero-thermodynamic parameters like pressure ratios, aerodynamic power, and efficiencies are computed and these results are compared with one another. The boundary conditions, convergence criterion, and turbulence model used in CFD computations are set uniform for comparison with 8 per cent turbulence intensity. Grid independence study is performed at design point to optimize the grid density for off-design performance predictions. ANSYS-CFX and PbCFD have predicted higher efficiency of 3.4% and 1.2% respectively with respect to targeted efficiency of 89 per cent.

The Effect of Heat Transfer Coefficient Increase on Tip Clearance Control in H.P. Compressors in Gas Turbine Engine

2013 ◽  
Author(s):  
Godwin Ita Ekong ◽  
Christopher A. Long ◽  
Peter R. N. Childs
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Time Constant ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Facility ◽  
Turbine Engine

Compressor tip clearance for a gas turbine engine application is the radial gap between the stationary compressor casing and the rotating blades. The gap varies significantly during different operating conditions of the engine due to centrifugal forces on the rotor and differential thermal expansions in the discs and casing. The tip clearance in the axial flow compressor of modern commercial civil aero-engines is of significance in terms of both mechanical integrity and performance. In general, the clearance is of critical importance to civil airline operators and their customers alike because as the clearance between the compressor blade tips and the casing increases, the aerodynamic efficiency will decrease and therefore the specific fuel consumption and operating costs will increase. This paper reports on the development of a range of concepts and their evaluation for the reduction and control of tip clearance in H.P. compressors using an enhanced heat transfer coefficient approach. This would lead to improvement in cruise tip clearances. A test facility has been developed for the study at the University of Sussex, incorporating a rotor and an inner shaft scaled down from a Rolls-Royce Trent aero-engine to a ratio of 0.7:1 with a rotational speed of up to 10000 rpm. The idle and maximum take-off conditions in the square cycle correspond to in-cavity rotational Reynolds numbers of 3.1×106 ≤ Reφ ≤ 1.0×107. The project involved modelling of the experimental facilities, to demonstrate proof of concept. The analysis shows that increasing the thermal response of the high pressure compressor (HPC) drum of a gas turbine engine assembly will reduce the drum time constant, thereby reducing the re-slam characteristics of the drum causing a reduction in the cold build clearance (CBC), and hence the reduction in cruise clearance. A further reduction can be achieved by introducing radial inflow into the drum cavity to further increase the disc heat transfer coefficient in the cavity; hence a further reduction in disc drum time constant.

scholarly journals Comprehensive report on Materials for Gas Turbine Engine Components

2019 ◽  
Vol 9 (2S2) ◽  
pp. 155-158
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Stresses ◽  
Prolonged Exposure ◽  
Raw Materials ◽  
Turbine Blades ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Engine Component

In the past three decades, it is very challenging for the researchers to design and development a best gas turbine engine component. Engine component has to face different operating conditions at different working environments. Nickel based superalloys are the best material to design turbine components. Inconel 718, Inconel 617, Hastelloy, Monel and Udimet are the common material used for turbine components. Directional solidification is one of the conventional casting routes followed to develop turbine blades. It is also reported that the raw materials are heat treated / age hardened to enrich the desired properties of the material implementation. Accordingly they are highly susceptible to mechanical and thermal stresses while operating. The hot section of the turbine components will experience repeated thermal stress. The halides in the combination of sulfur, chlorides and vanadate are deposited as molten salt on the surface of the turbine blade. On prolonged exposure the surface of the turbine blade starts to peel as an oxide scale. Microscopic images are the supportive results to compare the surface morphology after complete oxidation / corrosion studies. The spectroscopic results are useful to identify the elemental analysis over oxides formed. The predominant oxides observed are NiO, Cr2O3, Fe2O3 and NiCr2O4. These oxides are vulnerable on prolonged exposure and according to PB ratio the passivation are very less. In recent research, the invention on nickel based superalloys turbine blades produced through other advanced manufacturing process is also compared. A summary was made through comparing the conventional material and advanced materials performance of turbine blade material for high temperature performance.

Method for calculating the thrust and specific thrust of a double-flow gas turbine engine based on the results of tests at the laboratory unit «Flame»

2021 ◽  
pp. 58-64
Author(s):  
S.M. Sergeev ◽  
◽  
V.A. Kudriashov ◽  
N.V. Petrukhin ◽  
◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Similarity Criteria ◽  
Fuel Quality ◽  
Jet Engines ◽  
Laboratory Unit ◽  
Turbine Engine ◽  
Specific Thrust ◽  
The Cost

The main technical characteristics of jet engines depend on the fuel quality: thrust and fuel consumption. As a rule, the comparative assessment of real engines is carried by specific values. Specific thrust is one of the most important parameters of the gas turbine engine (GTE). The larger it is, the smaller the required air flow rate through the engine at a given thrust and therefore its dimensions and mass. To date, a system for evaluating the performance properties of fuels based on qualification methods has been created. However, these methods do not allow calculating the thrust and specific thrust of the engine and potentially assessing the effect of fuels on these characteristics. Therefore, the issues of efficient use of fuels for GTE are solved almost exclusively on the basis of tests at testing units with full-scale engines, which are carried out repeatedly, which leads to a significant increase in the cost of testing. The article proposes a method for calculating the thrust and specific thrust of a double-flow gas turbine engine according to the results of tests at a constant volume laboratory unit of bypass type “Flame”. The method is based on modeling the engine operating conditions using the similarity criteria of the bench reactor and the real engine and allows reducing significantly the material and time costs for testing. The experimental of the combustion characteristics of hydrocarbon fuels and the rated values of their thrust and specific thrust for a double-flow gas turbine engine are presented.

Modeling of Cyclic Life for Compressor Rotor of Gas Turbine Engine Taking Into Account Production Deviations

2020 ◽  
Author(s):  
Alexandr N. Arkhipov ◽  
Yury A. Ravikovich ◽  
Anton A. Matushkin ◽  
Dmitry P. Kholobtsev
Keyword(s):  
Gas Turbine ◽  
Low Cycle Fatigue ◽  
Probabilistic Modeling ◽  
Gas Turbine Engine ◽  
Critical Zone ◽  
Design Stage ◽  
Cyclic Life ◽  
Engine Operation ◽  
Turbine Engine ◽  
Compressor Rotor

Abstract The regional aircraft with a turbofan gas turbine engine, created in Russia, is successfully operated in the world market. Further increase of the life and reduction of the cost of the life cycle are necessary to ensure the competitive advantages of the engine. One of the units limiting the engine life is the compressor rotor. The cyclic life of the rotor depends on many factors: the stress-strain state in critical zones, the life of the material under low-cycle loading, the regime of engine operation, production deviations (within tolerances), etc. In order to verify the influence of geometry deviations, the calculations of the model with nominal dimensions and the model with the most unfavorable geometric dimensions (worst cases) have been carried out. The obtained influence coefficients for geometric and weight tolerances are then used for probabilistic modeling of stresses in the critical zone. Rotor speed and gas loads on the blades for different flight missions and engine wear are determined from the corresponding aerodynamic calculations taking into account the actual flight cycles (takeoff, reduction, reverse) and are also used for stress recalculations. The subsequent calculation of the rotor cyclic life and the resource assessment is carried out taking into account the spread of the material low-cycle fatigue by probabilistic modeling of the rotor geometry and weight loads. A preliminary assessment of the coefficients of tolerances influence on stress in the critical zone can be used to select the optimal (in terms of life) tolerances at the design stage. Taking into account the actual geometric and weight parameters can allow estimating the stress and expected life of each manufactured rotor.

Review of the von Karman Institute Compression Tube Facility for Turbine Research

2013 ◽  
Author(s):  
G. Paniagua ◽  
C. H. Sieverding ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Measurement Techniques ◽  
Gas Turbine Engine ◽  
Modern Technology ◽  
Forced Response ◽  
Engine Operation ◽  
Turbine Engine ◽  
Von Karman ◽  
Von Kármán

Advances in turbine-based engine efficiency and reliability are achieved through better knowledge of the mechanical interaction with the flow. The life-limiting component of a modern gas turbine engine is the high-pressure (HP) turbine stage due to the arduous environment. For the same reason, real gas turbine engine operation prevents fundamental research. Various types of experimental approaches have been developed to study the flow and in particular the heat transfer, cooling, materials, aero-elastic issues and forced response in turbines. Over the last 30 years short duration facilities have dominated the research in the study of turbine heat transfer and cooling. Two decades after the development of the von Karman Institute compression tube facility (built in the 90s), one could reconsider the design choices in view of the modern technology in compression, heating, control and electronics. The present paper provides first the history of the development and then how the wind tunnel is operated. Additionally the paper disseminates the experience and best practices in specifically designed measurement techniques to both experimentalists and experts in data processing. The final section overviews the turbine research capabilities, providing details on the required upgrades to the test section.

Investigation of Vapor-Phase Lubrication in a Gas Turbine Engine

1997 ◽  
Author(s):  
Kenneth W. Van Treuren ◽  
D. Neal Barlow ◽  
William H. Heiser ◽  
Matthew J. Wagner ◽  
Nelson H. Forster
Keyword(s):  
Gas Turbine ◽  
Vapor Phase ◽  
Gas Turbine Engine ◽  
Rolling Contact ◽  
Phosphate Ester ◽  
Lubrication System ◽  
Oil Lubrication ◽  
Vapor Phase Lubrication ◽  
Engine Operation ◽  
Turbine Engine

The liquid oil lubrication system of current aircraft jet engines accounts for approximately 10–15% of the total weight of the engine. It has long been a goal of the aircraft gas turbine industry to reduce this weight. Vapor-Phase Lubrication (VPL) is a promising technology to eliminate liquid oil lubrication. The current investigation resulted in the first gas turbine to operate in the absence of conventional liquid lubrication. A phosphate ester, commercially known as DURAD 620B, was chosen for the test. Extensive research at Wright Laboratory demonstrated that this lubricant could reliably lubricate railing element bearings in the gas turbine engine environment. The Allison T63 engine was selected as the test vehicle because of its small size and bearing configuration. Specifically, VPL was evaluated in the number eight bearing because it is located in a relatively hot environment, in line with the combustor discharge, and it can be isolated from the other bearings and the liquid lubrication system. The bearing was fully instrumented and its performance with standard oil lubrication was documented. Results of this baseline study were used to develop a thermodynamic model to predict the bearing temperature with VPL. The engine was then operated at a ground idle condition with VPL with the lubricant misted into the #8 bearing at 13 ml/hr. The bearing temperature stabilized at 283°C within 10 minutes. Engine operation was continued successfully for a total of one hour. No abnormal wear of the rolling contact surfaces was found when the bearing was later examined. Bearing temperatures after engine shutdown indicated the bearing had reached thermodynamic equilibrium with its surroundings during the test. After shutdown bearing temperatures steadily decreased without the soakback effect seen after shutdown in standard lubricated bearings. In contrast, the oil lubricated bearing ran at a considerably lower operating temperature (83°C) and was significantly heated by its surroundings after engine shutdown. In the baseline tests, the final bearing temperatures never reached that of the operating VPL system.

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