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.

Thermo Fluid Dynamic Analysis of a Gas Turbine Transition-Piece

2014 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Antonio Andreini ◽  
Lorenzo Mazzei ◽  
Giovanni Riccio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Fluid Dynamic ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Thermal Loads ◽  
Turbine Engine ◽  
Transition Piece

The transition-piece of a gas turbine engine is subjected to high thermal loads as it collects high temperature combustion products from the gas generator to a turbine. This generally produces high thermal stress levels in the casing of the transition piece, strongly limiting its life expectations and making it one of the most critical components of the entire engine. The reliable prediction of such thermal loads is hence a crucial aspect to increase the transition-piece life span and to assure safe operations. The present study aims to investigate the aero-thermal behaviour of a gas turbine engine transition-piece and in particular to evaluate working temperatures of the casing in relation to the flow and heat transfer situation inside and outside the transition-piece. Typical operating conditions are considered to determine the amount of heat transfer from the gas to the casing by means of CFD. Both conjugate approach and wall fixed temperature have been considered to compute the heat transfer coefficient, and more in general, the transition-piece thermal loads. Finally a discussion on the most convenient heat transfer coefficient expression is provided.

Study on Accuracy of Heat Transfer Coefficient Determination in the Bearing Chamber for Gas Turbine Engine

2020 ◽  
Author(s):  
Illia Petukhov ◽  
Taras Mykhailenko ◽  
Sergiy Yepifanov ◽  
Oleg Shevchuk
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Experimental Studies ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Cooling Medium ◽  
External Cooling

Abstract The heat transfer coefficient (HTC) is one of the key parameters that should be known at the stage of the bearing chamber design. This ensures safe temperature conditions for the lubrication oil and reliable operation of the gas turbine engine. The temperature gradient method is commonly used in experimental practice to determinate the HTC. The accuracy of the HTC determination is sensitive to changing of the bearing chamber operating conditions and should be analyzed at the stage of experimental studies planning. This paper presents a study on the accuracy of HTC determination when the external cooling of the bearing chamber is used to obtain the temperature difference sufficient for measurement. Three ways to reduce the relative error of the HTC determination in the bearing chamber were analyzed: i) decreasing the temperature measurement error; ii) decreasing the temperature of external cooling medium; iii) increasing the external heat transfer coefficient and contribution of wall thermal resistance optimization. For different operating conditions of the bearing chamber, the temperature of the outer wall that ensures the specified accuracy of the experimental HTC and the required parameters of the cooling medium were determined and recommended for practical implementation.

scholarly journals ОСОБЕННОСТИ ОБРАБОТКИ ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ ПРИ ОПРЕДЕЛЕНИИ КОЭФФИЦИЕНТА ТЕПЛООТДАЧИ В МАСЛЯНОЙ ПОЛОСТИ ОПОРЫ ГТД

2020 ◽  
pp. 73-81
Author(s):  
Илья Иванович Петухов ◽  
Тарас Петрович Михайленко ◽  
Андрей Александрович Брунак ◽  
Сергей Валерьевич Епифанов ◽  
Артём Викторович Ковалёв ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Temperature State ◽  
Wide Range ◽  
The Heat Transfer Coefficient

The development of gas turbine technology is accompanied by an increase in temperatures, pressures, and airflow velocity in the gas path. Increasing operating cycle parameters for gas turbine engine complicates the tasks of ensuring the permissible temperature state of engine parts, requires improving the methods of their calculation and design. This fact fully applies bearing assemblies, especially those operating in a hot environment, and causes interest in the study of thermohydraulic processes in the bearing chamber, which determines the temperature state of the rotor parts. The necessity of pressurizing the seals leads to the presence of the oil-air mixture in the bearing chamber. A wide range of operating parameters, flow inhomogeneity, phase disequilibrium, and phase separation significantly complicate the mathematical description of processes in the bearing chamber, including the use of CFD-modeling. Therefore, considerable attention is paid to experimental research. The experimental results are used not only to verify mathematical models but also to obtain generalizing dependencies. Most often, the desired value is the heat transfer coefficient in the oil cavity of the support. The article deals with the heat transfer features in the near-wall zone of the gas-turbine engine bearing chamber which were associated with the presence of oil-air flow. Also, approaches to the experimental determination of the heat transfer coefficient were analyzed and an appropriate system for measuring the local temperatures of the media was formed. The values of the error of the experimental heat transfer coefficient and the degree of influence of the determining factors were estimated. The contribution of the non-uniformity of the temperature field in the walls of the chamber and the uncertainty in the value of the temperature of the flow core was determined. The advantages of using the averaged heat transfer coefficient for engineering calculations and the significant influence of the averaging method on its value were also shown. Averaging over the heat flux density corresponds most accurately to the tasks of such calculations, at which the total heat flux through the chamber walls does not change.

The Relative Performance of External Casing Impingement Cooling Arrangements for Thermal Control of Blade Tip Clearance

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Myeonggeun Choi ◽  
David M. Dyrda ◽  
David R. H. Gillespie ◽  
Orpheas Tapanlis ◽  
Leo V. Lewis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Operating Conditions ◽  
Local Heat Transfer Coefficient ◽  
Tip Clearance ◽  
Local Cooling ◽  
Impingement Cooling

As a key way of improving jet engine performance, a thermal tip clearance control system provides a robust means of manipulating the closure between the casing and the rotating blade tips, reducing undesirable tip leakage flows. This may be achieved using an impingement cooling scheme on the external casing. Such systems can be optimized to increase the contraction capability for a given casing cooling flow. Typically, this is achieved by changing the cooled area and local casing features, such as the external flanges or the external cooling geometry. This paper reports the effectiveness of a range of impingement cooling arrangements in typical engine casing closure system. The effects of jet-to-jet pitch, number of jets, and inline and staggered alignment of jets on an engine representative casing geometry are assessed through comparison of the convective heat transfer coefficient distributions as well as the thermal closure at the point of the casing liner attachment. The investigation is primarily numerical, however, a baseline case has been validated experimentally in tests using a transient liquid crystal technique. Steady numerical simulations using the realizable k–ε, k–ω SST, and EARSM turbulence models were conducted to understand the variation in the predicted local heat transfer coefficient distribution. A constant mass flow rate was used as a constraint at each engine condition, approximately corresponding to a constant feed pressure when the manifold exit area is constant. Sets of local heat transfer coefficient data generated using a consistent modeling approach were then used to create reduced order distributions of the local cooling. These were used in a thermomechanical model to predict the casing closure at engine representative operating conditions.

The Relative Performance of External Casing Impingement Cooling Arrangements for Thermal Control of Blade Tip Clearance

2015 ◽  
Author(s):  
Myeonggeun Choi ◽  
David M. Dyrda ◽  
David R. H. Gillespie ◽  
Orpheas Tapanlis ◽  
Leo V. Lewis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Operating Conditions ◽  
Local Heat Transfer Coefficient ◽  
Tip Clearance ◽  
Local Cooling ◽  
Impingement Cooling

As a key way of improving jet engine performance, a thermal tip clearance control system provides a robust means of manipulating the closure between the casing and the rotating blade tips, reducing undesirable tip leakage flows. This may be achieved using an impingement cooling scheme on the external casing. Such systems can be optimized to increase the contraction capability for a given casing cooling flow. Typically this is achieved by changing the cooled area, local casing features such as the external flanges, or the external cooling geometry. This paper reports the effectiveness of a range of impingement cooling arrangements in typical engine casing closure system. The effects of jet-to-jet pitch, number of jets, inline and staggered alignment of jets, on an engine representative casing geometry are assessed through comparison of the convective heat transfer coefficient distributions as well as the thermal closure at the point of the casing liner attachment. The investigation is primarily numerical, however, a baseline case has been validated experimentally in tests using a transient liquid crystal technique. Steady numerical simulations using the realizable k-ε, k-ω SST and EARSM turbulence models were conducted to understand the variation in the predicted local heat transfer coefficient distribution. Constant mass flow rate was used as a constraint at each engine condition, this approximately pertaining to a constant feed pressure when the manifold exit area is constant. Sets of local heat transfer coefficient data generated using a consistent modelling approach were then used to create reduced order distributions of the local cooling. These were used in a thermo-mechanical model to predict the casing closure at engine representative operating conditions.

A Review of the Oxford Turbine Research Facility

2013 ◽  
Author(s):  
Kam Chana ◽  
Dave Cardwell ◽  
Terry Jones
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Short Duration ◽  
Research Effort ◽  
Gas Turbine Engine ◽  
Test Facility ◽  
Research Facility ◽  
Turbine Engine ◽  
Significant Research ◽  
Fundamental Research

Gas turbine engine efficiency and reliability is generally improved through better understanding and improvements to the design of individual components. The life limiting component of the modern gas turbine is the high pressure (HP) turbine stage due to the arduous environment. Over the last 50 years significant research effort has been focused on advancing blade cooling designs and materials. Due to practical limitations little fundamental research on the turbine system is performed in the operating gas turbine engine. Consequently different types of experimental approaches have been developed over the last 4 decades to study the flow and in particular the heat transfer and cooling in turbines. In general the facilities can be divided into continuous running or short duration and cascade or rotating. Over the last 30 years short duration facilities have dominated the research in the study of turbine heat transfer and cooling. The Oxford Turbine Research Facility (formerly known as the QinetiQ Turbine Test Facility, The Isentropic Light Piston Facility and The Isentropic Light Piston Cascade) is a short duration facility developed and built in the late 1970s and early 1980s for turbine heat transfer and cooling studies. This paper presents the developments and measurements taken on the facility over the last 35 years, including the type of research that has been conducted and, the current capability of the facility.

The Influence of Humidity on the Creep Life of a High Pressure Gas Turbine Blade: Part II—Case Study

2012 ◽  
Author(s):  
S. Eshati ◽  
P. Laskaridis ◽  
A. Haslam ◽  
P. Pilidis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Life Assessment ◽  
Coolant Temperature ◽  
Creep Life

The determination of the rate of heat transfer from the turbine blade in a cross flow is important in hot section gas turbine life assessment. For design purposes, the rate of heat transfer is normally fixed by semi-empirical correlations. These correlations require knowledge of fluid properties which depend on temperature. For gases these properties are normally available only for the dry state, thus the possible effect of the water vapour content has been overlooked. Many gas turbines operate in environments in which air humidity is very low and therefore has little influence on gas turbine performance. However humidity becomes more important in hot, humid climates where there are large variations in ambient absolute humidity, especially in hot and humid climates. The aim of this paper is to investigate and present the effect of humidity at different operating conditions on the turbine blade coolant heat transfer and blade creep life. The effect of humidity was considered only on the air coolant side. he The heat transfer coefficient on the hot side was calculated for dry hot gas. This avoided the balancing effect of each other (heat transfer coefficient coolant side and hot side). The WAR at each operating point is quantified based on the ambient temperature and the relative humidity (0%–100%). Results showed that with increasing WAR the blade inlet coolant temperature reduced along the blade span. The blade metal temperature at each section was reduced as WAR increased, which in turn increased the blade creep life. The increase in WAR increased the specific heat of the coolant and increased the heat transfer capacity of the coolant air flow. Different operating points were also evaluated at different WAR and Tamb to identify the effect of WAR on the creep life. The results showed that an increase in WAR increased the blade creep life. The creep life of the blade at each section of interest was obtained as a function of the blade section stress and the blade metal section temperature using the LMP approach.

scholarly journals Gas Turbine Main Shaft Internal Flow and Heat Transfer

1991 ◽  
Author(s):  
David V. Roscoe ◽  
Richard C. Buggeln ◽  
Peter M. Munsell ◽  
F. C. Hsing
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Wall Temperature ◽  
Internal Flow ◽  
Primary Objective ◽  
Turbine Engine ◽  
Cooling Flow ◽  
Low Pressure Turbine

A CFD analysis of the cooling flow through a gas turbine engine low pressure turbine shaft is presented. Three cases are considered in which throughflow and rotation rate are varied. The primary objective of the analysis was to derive improved heat transfer coefficient information, over those obtainable via semi-empirical means. The coefficients so obtained were then used in a one-dimensional, time-dependent analysis for use in predicting shaft wall temperature throughout a snap acceleration phase of the engine. A second objective was to obtain insight into the flow structure within the shaft with a view to possible design input in future engine programs. Results presented include detailed velocity vector plots at select locations, heat transfer coefficient distributions for each case and finally, for Case 2 predicted wall temperature vs. time is shown in conjunction with engine test data.

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