Adiabatic Effectiveness Measurements and Predictions of Leakage Flows Along a Blade Endwall

2005 ◽  
Vol 127 (3) ◽  
pp. 609-618 ◽  
Author(s):  
W. W. Ranson ◽  
K. A. Thole ◽  
F. J. Cunha
Keyword(s):  
High Pressure ◽  
Turbine Blades ◽  
Leakage Flow ◽  
Leakage Flows ◽  
High Pressure Compressor ◽  
Flow Through ◽  
Cooling Air ◽  
Low Speed Wind Tunnel ◽  
Paper Address ◽  
Good Agreement

Traditional cooling schemes have been developed to cool turbine blades using high-pressure compressor air that bypasses the combustor. This high-pressure forces cooling air into the hot main gas path through seal slots. While parasitic leakages can provide a cooling benefit, they also represent aerodynamic losses. The results from the combined experimental and computational studies reported in this paper address the cooling benefit from leakage flows that occur along the platform of a first stage turbine blade. A scaled-up, blade geometry with an upstream slot, a mid-passage slot, and a downstream slot was tested in a linear cascade placed in a low-speed wind tunnel. Results show that the leakage flow through the mid-passage gap provides only a small cooling benefit to the platform. There is little to no benefit to the blade platform that results by increasing the coolant flow through the mid-passage gap. Unlike the mid-passage gap, leakage flow from the upstream slot provides good cooling to the platform surface, particularly in certain regions of the platform. Relatively good agreement was observed between the computational and experimental results, although computations overpredicted the cooling.

Adiabatic Effectiveness Measurements and Predictions of Leakage Flows Along a Blade Endwall

2004 ◽  
Author(s):  
W. W. Ranson ◽  
K. A. Thole ◽  
F. J. Cunha
Keyword(s):  
High Pressure ◽  
Turbine Blades ◽  
Leakage Flow ◽  
Leakage Flows ◽  
High Pressure Compressor ◽  
Flow Through ◽  
Cooling Air ◽  
Low Speed Wind Tunnel ◽  
Paper Address ◽  
Good Agreement

Traditional cooling schemes have been developed to cool turbine blades using high-pressure compressor air that bypasses the combustor. This high pressure forces cooling air into the hot main gas path through seal slots. While parasitic leakages can provide a cooling benefit, they also represent aerodynamic losses. The results from the combined experimental and computational studies reported in this paper address the cooling benefit from leakage flows that occur along the platform of a first stage turbine blade. A scaled-up, blade geometry with an upstream slot, a mid-passage slot, and a downstream slot was tested in a linear cascade placed in a low speed wind tunnel. Results show that the leakage flow through the mid-passage gap provides only a small cooling benefit to the platform. There is little to no benefit to the blade platform that results by increasing the coolant flow through the mid-passage gap. Unlike the mid-passage gap, leakage flow from the upstream slot provides good cooling to the platform surface, particularly in certain regions of the platform. Relatively good agreement was observed between the computational and experimental results although computations overpredicted the cooling.

Part II. Research on the Performance of a Type of Internally Air-cooled Turbine Blade

1953 ◽  
Vol 167 (1) ◽  
pp. 351-370 ◽  
Author(s):  
D. G. Ainley
Keyword(s):  
Gas Flow ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Small Diameter ◽  
Rotor Blades ◽  
Air Cooling ◽  
Gas Temperature ◽  
Flow Through ◽  
Cooling Air ◽  
Practical Feasibility

A comprehensive series of tests have been made on an experimental single-stage turbine to determine the cooling characteristics and the overall stage performance of a set of air-cooled turbine blades. These blades, which are described fully in Part I of this paper had, internally, a multiplicity of passages of small diameter along which cool air was passed through the whole length of the blade. Analysis of the, test data indicated that, when a quantity of cooling air amounting to 2 per cent, by weight, of the total gas-flow through the turbine is fed to the row of rotor blades, an increase in gas temperature of about 270 deg. C. (518 deg. F.) should be permissible above the maximum allowable value for a row of uncooled blades made from the same material. The degree of cooling achieved throughout each blade was far from uniform and large thermal stresses must result. It appears, however, that the consequences of this are not highly detrimental to the performance of the present type of blading, it being demonstrated that the main effect of the induced thermal stress is apparently to transfer the major tensile stresses to the cooler (and hence stronger) regions of the blade. The results obtained from the present investigations do not represent a limit to the potentialities of internal air-cooling, but form merely a first exploratory step. At the same time the practical feasibility of air cooling is made apparent, and advances up to the present are undoubtedly encouraging.

Influence of a Shroud Axisymmetric Slot Injection on a High Pressure Turbine Flow

2016 ◽  
Author(s):  
Etienne Tang ◽  
Mickaël Philit ◽  
Gilles Leroy ◽  
Isabelle Trebinjac ◽  
Ghislaine Ngo Boum
Keyword(s):  
High Pressure ◽  
Incidence Angle ◽  
Main Stream ◽  
High Pressure Turbine ◽  
Unsteady Rans ◽  
Flow Through ◽  
Definition Of ◽  
Cooling Air ◽  
Ideal Process ◽  
Mixing Losses

This paper focuses on an axisymmetric slot injecting cooling air at the casing between the stator and the rotor in a one-stage unshrouded transonic high pressure turbine. This configuration has been studied with the help of unsteady RANS computations with and without the slot. Special care has been taken to model and describe the interaction induced unsteady mechanisms. It has been found that the cooling air is ejected from the axisymmetric slot at a fixed position with respect to the stator vanes, with a much lower incidence angle than the main stream. The flow through the rotor passage is highly modified and reveals an unsteady behaviour which highlights the necessity of using unsteady simulations in order to accurately model such a configuration. The effect on the efficiency and on the repartition of loss generation has been determined. As several different definitions of the efficiency can be used for cooled turbine cases, this choice is discussed. In particular, Young & Horlock’s “Weighted Pressure” definition, which takes into account some unavoidable mixing losses in the definition of the ideal process, is evaluated. With this definition, the slot does not yield any significant decrease in overall efficiency.

Theoretical Modelling of Relative Wall Motion Effects in Tip Leakage Flow

1995 ◽  
Author(s):  
I. K. Nikolos ◽  
D. I. Douvikas ◽  
K. D. Papailiou
Keyword(s):  
Wall Motion ◽  
Tip Clearance ◽  
Calculation Procedure ◽  
Theoretical Modelling ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Complete Calculation ◽  
Flow Through ◽  
Good Agreement

The influence of relative wall motion in modifying the leakage flow through the tip clearance is investigated. A theoretical model is developed, in order to calculate the mass flow rate through the gap. The physical mechanism by which relative wall motion affects the leakage flow is analyzed and the differences between the turbine and compressor case are identified. This model, being an extension of an already existing one, not taking into account relative wall motion, is incorporated into the tip clearance calculation procedure, already developed by the authors. Theoretical results of the complete calculation procedure (secondary flow plus tip clearance model) are compared with experimental data, for the case of compressor and turbine cascades, as well as for the case of a single rotor. Good agreement between theory and experiment is obtained.

scholarly journals Automated Welding of Turbine Blades

1989 ◽  
Author(s):  
J. Liburdi ◽  
P. Lowden ◽  
C. Pilcher
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Heat Input ◽  
Turbine Blades ◽  
Welding Parameters ◽  
Weld Deposit ◽  
Low Pressure Turbine ◽  
High Pressure Compressor ◽  
Automation Technology ◽  
Pressure Compressor

The welding of superalloys has been regarded, generally, as an art requiring the highest degree of welder skill and discipline. These highly alloyed materials are prone to micro-cracking and, in some cases, even the best welders cannot achieve satisfactory results. Now, however, advances in automation technology have made it possible to program precisely the complex airfoil shapes and the welding parameters. Consequently, turbine blades can be welded in a repeatable manner, with a minimum of heat input resulting in better metallurgical quality both in the base metal and the weld deposit. The application of this technology to the automated welding of high-pressure compressor turbine blade tips, and the refurbishment of low-pressure turbine blade shrouds are presented in this paper.

Experimental Study of Leakage Flow on Flow Field and Film Cooling of High Pressure Turbine Blade Platform

2015 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Yutaka Oda ◽  
Shintaro Kozono
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Turbine Blades ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Temperature Fields ◽  
Leakage Flow ◽  
High Pressure Turbine ◽  
Film Cooling Effectiveness ◽  
Injection Angle

An experiment has been conducted to study stator/rotor disc cavity leakage flow on the platform of a highly loaded stationary linear blade cascade. The linear cascade consists of a scaled-up model of the high-pressure turbine blades of an E3 (Energy efficient engine) and leakage slot models installed under the platform. Experiments have been conducted to investigate the effect of the slot injection angle, leakage flow rates, distance between the leading edge of the blade and the slot, and spacing of the blades. The film-cooling effectiveness was measured by pressure sensitive paint (PSP), and the temperature fields and flow fields were investigated using laser-induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. It was observed from the experiments that the leakage flow covered the surface of the blade platform when the distance between the leading edge and the slot was zero; however, with increasing distance, the horseshoe vortex dominates near the junction of the blade leading edge, and the leakage flow could not cover the region. It was also found that the leakage flow has an effect that promotes the formation of the horseshoe vortex for some experimental conditions.

Automated Welding of Turbine Blades

1990 ◽  
Vol 112 (4) ◽  
pp. 550-554
Author(s):  
J. Liburdi ◽  
P. Lowden ◽  
C. Pilcher
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Heat Input ◽  
Turbine Blades ◽  
Welding Parameters ◽  
Weld Deposit ◽  
Low Pressure Turbine ◽  
High Pressure Compressor ◽  
Automation Technology ◽  
Pressure Compressor

The welding of superalloys has been regarded, generally, as an art requiring the highest degree of welder skill and discipline. These highly alloyed materials are prone to micro-cracking and, in some cases, even the best welders cannot achieve satisfactory results. Now, however, advances in automation technology have made it possible to program precisely the complex airfoil shapes and the welding parameters. Consequently, turbine blades can be welded in a repeatable manner, with a minimum of heat input, resulting in better metallurgical quality both in the base metal and the weld deposit. The application of this technology to the automated welding of high-pressure compressor turbine blade tips and the refurbishment of low-pressure turbine blade shrouds are presented in this paper.

Theory and Application of Axisymmetric Endwall Contouring for Compressors

2011 ◽  
Author(s):  
Georg Kro¨ger ◽  
Christian Voß ◽  
Eberhard Nicke ◽  
Christian Cornelius
Keyword(s):  
High Pressure ◽  
Pressure Gradient ◽  
Gas Turbine ◽  
Static Pressure ◽  
Aerodynamic Performance ◽  
Leakage Flow ◽  
High Pressure Compressor ◽  
Blade Tip ◽  
Stage Efficiency ◽  
Pressure Compressor

Engine operating range and efficiency are of increasing importance in modern compressor design for heavy duty gas turbines and aircraft engines. These highly challenging objectives can only be met if all components provide high aerodynamic performance and stability. The aerodynamic losses of highly loaded axial compressors are mainly influenced by the leakage flow through clearance gaps. Especially the leakage flow due to the radial clearances of rotor blades affects negatively both, the efficiency and the operating range of the engine. Recent publications showed that the clearance flow and the clearance vortex can be influenced by an additional static pressure gradient at the outer casing, which is created by an axisymmetric wavy casing shape. A notable performance increase of up to 0.4% stage efficiency at design point conditions was reported for high pressure stages with large tip clearance heights [1] as well as for a transonic stage with a relatively small radial clearance gap [2]. An analytic approach to predict the effects of axisymmetric casing contouring has been developed at DLR, Institute of Propulsion Technology, and is outlined in the first part of this work. The characteristic behavior of the clearance vortex in an adverse pressure gradient is discussed by means of an inviscid vortex model [3]. The critical vortex parameters are isolated and related to the static pressure increase due to the casing contour. The second part illustrates the application of an axisymmetric endwall contour. A three dimensional optimization of the outer casing and the corresponding blade tip airfoil section of a typical gas turbine high pressure compressor stage with a high number of free variables is presented. The optimization led to a significant increase in aerodynamic performance of about 0.8% stage efficiency and to a notable reduction of the endwall blockage at ADP conditions. Furthermore, an improved off-design performance was found and a simple design rule is given to transfer both, the casing contour and the blade tip section modification on similar high pressure compressor blades. Based on these design rules the results of the optimized stages were applied to the rear stages of a Siemens gas turbine compressor CFD model. An increase of 0.3% full compressor performance was reached at design point conditions.

Effect of Trailing-Edge Ejection on Local Heat (Mass) Transfer in Pin Fin Cooling Channels in Turbine Blades

1994 ◽  
Vol 116 (1) ◽  
pp. 159-168 ◽  
Author(s):  
R. D. McMillin ◽  
S. C. Lau
Keyword(s):  
Mass Transfer ◽  
Gas Turbine ◽  
Heat Mass Transfer ◽  
Turbine Blades ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Flow Through ◽  
Straight Flow ◽  
Cooling Air

Experiments are conducted to study the local heat transfer distribution and pressure drop in a pin fin channel that models the cooling passages in modern gas turbine blades. The detailed heat/mass transfer distribution is determined via the naphthalene sublimation technique for flow through a channel with a 16-row, staggered 3 × 2 array of short pin fins (with a height-to-diameter ratio of 1.0, and streamwise and spanwise spacing-to-diameter ratios of 2.5) and with flow ejection through holes in one of the side walls and at the straight flow exit (to simulate ejection through holes along the trailing edges and through tip bleed holes of turbine blades). The pin fin heat/mass transfer and the channel wall heat/mass transfer are obtained for the straight-flow-only and the ejection-flow cases. The results show that the regional pin heat/mass transfer coefficients are generally higher than the corresponding regional wall heat/mass transfer coefficients in both cases. When there is side wall flow ejection, a portion of the flow turns to exit through the ejection holes and the rate of heat/mass transfer decreases in the straight flow direction as a result of the reducing mass flow rate along the channel. The rate of cooling air flow through a pin fin channel in a gas turbine blade must be increased to compensate for the “loss” of the cooling air through trailing edge ejection holes, so that the blade tip is cooled sufficiently.

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