Impact of Severe Temperature Distortion on Turbine Efficiency

2011 ◽  
Author(s):  
Paul F. Beard ◽  
Andy Smith ◽  
Thomas Povey
Keyword(s):  
Computational Study ◽  
Measurement Techniques ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Turbine Efficiency ◽  
External Flows ◽  
Torque Transducer ◽  
Formed Part ◽  
Low Uncertainty ◽  
The Eu

This paper presents an experimental and computational study of the effect of severe inlet temperature distortion (hot streaks) on the efficiency of the MT1 HP turbine, which is a highly-loaded unshrouded transonic design. The experiments were performed in the Oxford Turbine Research Facility (OTRF) (formerly the TTF at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, and Tgas/Twall and N/T01 are matched to engine conditions. The research formed part of the EU Turbine Aero-Thermal External Flows (TATEF II) programme. An advanced second generation temperature distortion simulator was developed for this investigation, which allows both radial and circumferential temperature profiles to be simulated. A pronounced profile was used for this study. The system was novel in that it was designed to be compatible with an efficiency measurement system which was also developed for this study. To achieve low uncertainty (bias and precision errors of approximately 1.5 per cent and 0.2 per cent respectively, to 95 per cent confidence), the mass flow rate of the hot and cold streams used to simulate temperature distortion were independently metered upstream of the turbine nozzle using traceable measurement techniques. Turbine power was measured directly with an accurate torque transducer. The efficiency of the test turbine was evaluated experimentally for a uniform inlet temperature condition, and with pronounced temperature distortion. Mechanisms for observed changes in the turbine exit flow field and efficiency are discussed. The data are compared in terms of flow structure to full stage CFD performed using the Rolls Royce Hydra code.

Impact of Severe Temperature Distortion on Turbine Efficiency

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Paul F. Beard ◽  
Andy Smith ◽  
Thomas Povey
Keyword(s):  
Computational Study ◽  
Measurement Techniques ◽  
Inlet Temperature ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
External Flows ◽  
Torque Transducer ◽  
Formed Part ◽  
Low Uncertainty ◽  
The Eu

This paper presents an experimental and computational study of the effect of severe inlet temperature distortion (hot streaks) on the efficiency of the MT1 HP turbine, which is a highly-loaded unshrouded transonic design. The experiments were performed in the Oxford Turbine Research Facility (OTRF) (formerly the TTF at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, Tgas/Twall and N/T01 are matched to engine conditions. The research formed part of the EU Turbine Aero-Thermal External Flows (TATEF II) program. An advanced second generation temperature distortion simulator was developed for this investigation, which allows both radial and circumferential temperature profiles to be simulated. A pronounced profile was used for this study. The system was novel in that it was designed to be compatible with an efficiency measurement system which was also developed for this study. To achieve low uncertainty (bias and precision errors of approximately 1.5% and 0.2% respectively, to 95% confidence), the mass flow rate of the hot and cold streams used to simulate temperature distortion were independently metered upstream of the turbine nozzle using traceable measurement techniques. Turbine power was measured directly with an accurate torque transducer. The efficiency of the test turbine was evaluated experimentally for a uniform inlet temperature condition, and with pronounced temperature distortion. Mechanisms for observed changes in the turbine exit flow field and efficiency are discussed. The data are compared in terms of flow structure to full stage computational fluid dynamics (CFD) performed using the Rolls Royce Hydra code.

Experimental and computational fluid dynamics investigation of the efficiency of an unshrouded transonic high pressure turbine

2011 ◽  
Vol 225 (8) ◽  
pp. 1166-1179 ◽  
Author(s):  
P F Beard ◽  
A D Smith ◽  
T Povey
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Short Duration ◽  
Computational Study ◽  
Experimental Result ◽  
Test Facility ◽  
Turbine Efficiency ◽  
External Flows ◽  
Formed Part ◽  
The Eu

This article presents an experimental and computational study of the efficiency of an unshrouded transonic turbine. This research formed part of the EU Turbine Aero-Thermal External Flows II programme. The experiments were performed in the Oxford Turbine Research Facility (previously the Turbine Test Facility at QinetiQ, Farnborough). This facility is an engine scale, short duration, rotating transonic facility, in which M, Re, [Formula: see text], and [Formula: see text] are matched to engine conditions. For these experiments, the MT1 turbine stage was installed. Historically, turbine efficiency measurements are conducted in steady state adiabatic facilities. However, short-duration facilities allow simultaneous aerodynamic and heat transfer measurements with a significant reduction in cost. An efficiency measurement system was developed for this investigation, and this is briefly described. The system allows efficiency to be evaluated to bias and precision errors of approximately ±1.45 per cent and ±0.16 per cent, respectively, to 95 per cent confidence. The results of accurate area surveys of the turbine inlet and exit flows are presented and discussed. At the turbine exit, data were taken at two traverse planes, approximately 0.5 and 4.5 rotor axial chords downstream of the rotor. The turbine efficiency was experimentally evaluated based on the data at both planes, using a number of mixing models, which are discussed and compared. The experimental result of turbine efficiency is also compared to that estimated from a mean-line prediction. Full-stage steady and unsteady computational fluid dynamics of the experiment using the Rolls-Royce HYDRA code was conducted and is also presented. The predicted and measured rotor exit flow-fields are compared at both downstream traverse planes.

Effect of Combustor Swirl on Transonic High Pressure Turbine Efficiency

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Paul F. Beard ◽  
Andy D. Smith ◽  
Thomas Povey
Keyword(s):  
High Pressure ◽  
Computational Study ◽  
Pressure Ratio ◽  
High Pressure Turbine ◽  
Turbine Efficiency ◽  
Baseline Case ◽  
Inlet Swirl ◽  
Computational Fluid Dynamics Cfd ◽  
External Flows ◽  
The Eu

This paper presents an experimental and computational study of the effect of inlet swirl on the efficiency of a transonic turbine stage. The efficiency penalty is approximately 1%, but it is argued that this could be recovered by correct design. There are attendant changes in capacity, work function, and stage total-to-total pressure ratio, which are discussed in detail. Experiments were performed using the unshrouded MT1 high-pressure turbine installed in the Oxford Turbine Research Facility (OTRF) (formerly at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, Tgas/Twall, and N/T01 are matched to engine conditions. The research was conducted under the EU Turbine Aero-Thermal External Flows (TATEF II) program. Turbine efficiency was experimentally determined to within bias and precision uncertainties of approximately ±1.4% and ±0.2%, respectively, to 95% confidence. The stage mass flow rate was metered upstream of the turbine nozzle, and the turbine power was measured directly using an accurate strain-gauge based torque measurement system. The turbine efficiency was measured experimentally for a condition with uniform inlet flow and a condition with pronounced inlet swirl. Full stage computational fluid dynamics (CFD) was performed using the Rolls-Royce Hydra solver. Steady and unsteady solutions were conducted for both the uniform inlet baseline case and a case with inlet swirl. The simulations are largely in agreement with the experimental results. A discussion of discrepancies is given.

The Effect of Hot-Streaks on HP Vane Surface and Endwall Heat Transfer: An Experimental and Numerical Study

2005 ◽  
Author(s):  
T. Povey ◽  
K. S. Chana ◽  
T. V. Jones ◽  
J. Hurrion
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling System ◽  
Numerical Study ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Wall Heat Transfer ◽  
Hot Streak ◽  
End Wall

Pronounced non-uniformities in combustor exit flow temperature (hot-streaks), which arise because of discrete injection of fuel and dilution air jets within the combustor and because of end-wall cooling flows, affect both component life and aerodynamics. Because it is very difficult to quantitatively predict the affects of these temperature non-uniformities on the heat transfer rates, designers are forced to budget for hot-streaks in the cooling system design process. Consequently, components are designed for higher working temperatures than the mass-mean gas temperature, and this imposes a significant overall performance penalty. An inadequate cooling budget can lead to reduced component life. An improved understanding of hot-streak migration physics, or robust correlations based on reliable experimental data, would help designers minimise the overhead on cooling flow that is currently a necessity. A number of recent research projects sponsored by a range of industrial gas turbine and aero-engine manufacturers attest to the growing interest in hot-streak physics. This paper presents measurements of surface and end-wall heat transfer rate for an HP nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular transonic rotating turbine facility. Measurements were conducted with both uniform stage inlet temperature and with two non-uniform temperature profiles. The temperature profiles were non-dimensionally similar to profiles measured in an engine. A difference of one half of an NGV pitch in the circumferential (clocking) position of the hot-streak with respect to the NGV was used to investigate the affect of clocking on the vane surface and end-wall heat transfer rate. The vane surface pressure distributions, and the results of a flow-visualisation study, which are also given, are used to aid interpretation of the results. The results are compared to two-dimensional predictions conducted using two different boundary layer methods. Experiments were conducted in the Isentropic Light Piston Facility (ILPF) at QinetiQ Farnborough, a short duration engine-size turbine facility. Mach number, Reynolds number and gas-to-wall temperature ratios were correctly modelled. It is believed that the heat transfer measurements presented in this paper are the first of their kind.

Conjugate heat transfer study of backdisc cooling of a radial turbine

2020 ◽  
pp. 095440702094754
Author(s):  
MA Chao ◽  
LU Kangbo ◽  
LI Wenjiao
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Turbine Rotor ◽  
Inlet Temperature ◽  
Turbine Cooling ◽  
Turbine Efficiency ◽  
Geometric Configurations ◽  
Cooling Method ◽  
Emission Regulations ◽  
Engine Emission

Radial turbines used in turbochargers and micro-turbines are subjected to high inlet temperature. This creates high thermal stress in the turbines, and possible creep of turbine inducer blades, and can reduce turbines’ reliability. With the ever-stringent engine emission regulations and the continuous drive for engine power density, turbine inlet temperature is significantly increased recently and the risk of thermo-mechanical failure of turbine rotor is heightened. To solve this problem, an innovative turbine cooling method is proposed by injecting a small amount of compressor or intercooler discharge air onto the upper backdisc region of turbine rotor to cool the disc and the inducer blades. A conjugate heat transfer simulation was carried out to investigate the effects of this cooling method with a turbocharger turbine. Flow conditions and geometric configurations were investigated for their influences on the cooling effectiveness of the method. The results show that using the compressor discharger air after intercooler with only 0.5–2.0% of turbine mass flow, the averaged cooling efficiency of the turbine backdisc is promoted by 23–43%; only four to six jets may be needed to cool the entire backdisc; and turbine efficiency is reduced by less than 1% point.

The Effect of Hot-Streaks on HP Vane Surface and Endwall Heat Transfer: An Experimental and Numerical Study

2005 ◽  
Vol 129 (1) ◽  
pp. 32-43 ◽  
Author(s):  
T. Povey ◽  
K. S. Chana ◽  
T. V. Jones ◽  
J. Hurrion
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling System ◽  
Numerical Study ◽  
Guide Vane ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Gas Temperature ◽  
Hot Streak

Pronounced nonuniformities in combustor exit flow temperature (hot-streaks), which arise because of discrete injection of fuel and dilution air jets within the combustor and because of endwall cooling flows, affect both component life and aerodynamics. Because it is very difficult to quantitatively predict the effects of these temperature nonuniformities on the heat transfer rates, designers are forced to budget for hot-streaks in the cooling system design process. Consequently, components are designed for higher working temperatures than the mass-mean gas temperature, and this imposes a significant overall performance penalty. An inadequate cooling budget can lead to reduced component life. An improved understanding of hot-streak migration physics, or robust correlations based on reliable experimental data, would help designers minimize the overhead on cooling flow that is currently a necessity. A number of recent research projects sponsored by a range of industrial gas turbine and aero-engine manufacturers attest to the growing interest in hot-streak physics. This paper presents measurements of surface and endwall heat transfer rate for a high-pressure (HP) nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular transonic rotating turbine facility. Measurements were conducted with both uniform stage inlet temperature and with two nonuniform temperature profiles. The temperature profiles were nondimensionally similar to profiles measured in an engine. A difference of one-half of an NGV pitch in the circumferential (clocking) position of the hot-streak with respect to the NGV was used to investigate the affect of clocking on the vane surface and endwall heat transfer rate. The vane surface pressure distributions, and the results of a flow-visualization study, which are also given, are used to aid interpretation of the results. The results are compared to two-dimensional predictions conducted using two different boundary layer methods. Experiments were conducted in the Isentropic Light Piston Facility (ILPF) at QinetiQ Farnborough, a short-duration engine-sized turbine facility. Mach number, Reynolds number, and gas-to-wall temperature ratios were correctly modeled. It is believed that the heat transfer measurements presented in this paper are the first of their kind.

Passive Shroud Cooling Concepts for HP Turbines: Experimental Investigations

2006 ◽  
Author(s):  
Vasudevan Kanjirakkad ◽  
Richard Thomas ◽  
Howard Hodson ◽  
Erik Janke ◽  
Frank Haselbach ◽  
...  
Keyword(s):  
Film Cooling ◽  
Alternative Methods ◽  
Passive Cooling ◽  
Experimental Investigations ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
High Pressure Turbine ◽  
Turbine Inlet Temperature ◽  
Critical Areas ◽  
Cooling Method

The cooling of rotor shrouds in the first stage of a high-pressure turbine requires special attention as flatter turbine inlet temperature profiles and more highly loaded blades result in increased thermal and mechanical stresses. The use of film cooling and/or internal convective cooling makes the rotor shroud heavier and oversized, restricting the maximum rotational speed. Alternative methods are therefore sought to achieve improved cooling of the shroud. This paper discusses the low speed experimental investigation of two ‘passive’ cooling concepts known as ‘rail cooling’ and ‘platform cooling’. It has been shown experimentally that the modified cooling method, namely the platform cooling, substantially improves the rotor shroud coolant distribution in the critical areas whilst employing significantly lower amounts of coolant.

Effects of Inlet Temperature Gradients on Turbomachinery Performance

1975 ◽  
Vol 97 (1) ◽  
pp. 64-71 ◽  
Author(s):  
B. Lakshminarayana
Keyword(s):  
Combustion Chamber ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Secondary Flows ◽  
Temperature Gradients ◽  
Large Temperature ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Blade Row

An analysis is carried out to predict the nature and magnitude of secondary flows induced by temperature gradients in turbomachinery stator and rotor. The effect of this thermal driven secondary flow is severe in gas turbines, due to large temperature gradients that exist at the outlet of the combustion chamber. Secondary flows change the temperature profiles at the exit of the blade row and generate thermal wakes. A method of incorporating these effects into the calculation of gas, blade and casing temperatures in a turbine is demonstrated through an example.

The Influence of Shroud and Cavity Geometry on Turbine Performance: An Experimental and Computational Study—Part I: Shroud Geometry

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Budimir Rosic ◽  
John D. Denton ◽  
Eric M. Curtis
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Leading Edge ◽  
Leakage Flow ◽  
Cavity Depth ◽  
Industrial Practice ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Mainstream Flow ◽  
Mass Fractions

Imperfections in the turbine annulus geometry, caused by the presence of the shroud and associated cavity, have a significant influence on the aerodynamics of the main passage flow path. In this paper, the datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested. The study was carried out using a three-dimensional multiblock solver, which modeled the flow in a 1.5 stage turbine. The following geometry parameters were varied: inlet and exit cavity length, shroud overhang upstream of the rotor leading edge and downstream of the trailing edge, shroud thickness for fixed casing geometry and shroud cavity depth, and shroud cavity depth for the fixed shroud thickness. The aim of this study was to investigate the influence of the above geometric modifications on mainstream aerodynamics and to obtain a map of the possible turbine efficiency changes caused by different shroud geometries. The paper then focuses on the influence of different leakage flow fractions on the mainstream aerodynamics. This work highlighted the main mechanisms through which leakage flow affects the mainstream flow and how the two interact for different geometrical variations and leakage flow mass fractions.

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