Effect of Airfoil Shape and Turning Angle on Turbine Airfoil Aerodynamic Performance at Transonic Conditions

2011 ◽  
Author(s):  
Santosh Abraham ◽  
Kapil Panchal ◽  
Srinath V. Ekkad ◽  
Wing Ng ◽  
Barry J. Brown ◽  
...  
Keyword(s):  
Mach Number ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Airfoil Surface ◽  
Turning Angle ◽  
Gas Turbine Blades ◽  
Mach Numbers ◽  
Exit Mach Number ◽  
Turbine Airfoils

Performance data for high turning gas turbine blades under transonic Mach numbers is significantly lacking in literature. Performance of three gas turbine airfoils with varying turning angles at transonic flow conditions was investigated in this study. Midspan total pressure loss, secondary flow field and static pressure measurements on the airfoil surface in a linear cascade setting were measured. Airfoil curvature and true chord were varied to change the loading vs. chord for each airfoil. Airfoils A, D and E are designed to operate at different velocity triangles. Velocity triangle requirements (inlet/exit Mach number and gas angles) come from 1D and 2D models that include calibrated loss systems. One of the goals of this study was to use the experimental data to confirm/refine loss predictions for the effect of various Mach numbers and gas turning angles. The cascade exit Mach numbers were varied within a range from 0.6 to 1.1. The airfoil turning angle ranges from 120° to 138°. A realistic inlet/exit Mach number ratio, that is representative of that seen in a real engine, was obtained by reducing the inlet span with respect to the exit span of the airfoil, thereby creating a quasi 2D cascade. In order to compare the experimental results and study the detailed flow characteristics, 3D viscous compressible CFD analysis was also carried out.

Effect of Turbine Airfoil Shape on Aerodynamic Losses for Turbine Airfoils Operating Under Transonic Conditions

2011 ◽  
Author(s):  
Santosh Abraham ◽  
Kapil Panchal ◽  
Srinath V. Ekkad ◽  
Wing Ng ◽  
Barry J. Brown ◽  
...  
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Loss ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Airfoil Surface ◽  
Mach Numbers ◽  
Exit Mach Number ◽  
Turbine Airfoils ◽  
Turbine Design

Profile and secondary loss correlations have been developed and improved over the years to include the induced incidence and leading edge geometry and to reflect recent trends in turbine design. All of these investigations have resulted in better understanding of the flow field in turbine passages. However, there is still insufficient data on the performance of turbine airfoils with high turning angles operating at varying incidence angles at transonic Mach numbers. The paper presents detailed aerodynamic measurements for three different turbine airfoils with similar turning angles but different aerodynamic shapes. Midspan total pressure loss, secondary flow field, and static pressure measurements on the airfoil surface in the cascades are presented and compared for the three different airfoil sets. The airfoils are designed for the same velocity triangles (inlet/exit gas angles and Mach number). Airfoil curvature and true chord are varied to change the loading vs. chord. The objective is to investigate the type of loading distribution and its effect on aerodynamic performance (pressure loss). Measurements are made at +10, 0 and −10 degree incidence angles for high turning turbine airfoils with ∼127 degree turning. The cascade exit Mach numbers were varied within a range from 0.6 to 1.1. In order to attain a ratio of inlet Mach number to exit Mach number that is representative to that encountered in a real engine, the exit span is increased relative to the inlet span. This results in one end wall diverging from inlet to exit at a 13 degree angle, which simulates the required leading edge loading as seen in an engine. 3D viscous compressible CFD analysis was carried out in order to compare the results with experimentally obtained values and to further investigate the flow characteristics of the airfoils under study.

Experimental and Numerical Investigations of a Transonic, High Turning Turbine Cascade With a Divergent Endwall

2010 ◽  
Author(s):  
Santosh Abraham ◽  
Kapil Panchal ◽  
Song Xue ◽  
Srinath V. Ekkad ◽  
Wing Ng ◽  
...  
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Leading Edge ◽  
Design Flow ◽  
Cfd Analysis ◽  
Airfoil Surface ◽  
Mach Numbers ◽  
End Wall

The paper presents detailed measurements of midspan total pressure loss, secondary flow field, static pressure measurements on airfoil surface at midspan, near hub and near the end walls in a transonic turbine airfoil cascade. Numerous low-speed experimental studies have been carried out to investigate the performance of turbine cascades. Profile and secondary loss correlations have been developed and improved over the years to include the induced incidence and leading edge geometry and to reflect recent trends in turbine design. All of the above investigations have resulted in better understanding of flow field in turbine passages. However, there is still insufficient data on the performance of turbine blades with high turning angles operating at varying incidences angles at transonic Mach numbers. In the present study, measurements were made at +10, 0 and −10 degree incidence angles for a high turning turbine airfoil with 127 degree turning. The exit Mach numbers were varied within a range from 0.6 to 1.1. Additionally, the exit span is increased relative to the inlet span resulting in one end wall diverging from inlet to exit at 13 degree angle. This was done in order to obtain a ratio of inlet Mach number to exit Mach number which is representative to that encountered in real engine and simulates the blade and near end wall loading that is seen in an engine. 3D viscous compressible CFD analysis was carried out in order to compare the results with experimentally obtained values and to further investigate the design and off-design flow characteristics of the airfoil under study. All aerodynamic measurements were compared with CFD analysis and a reasonably good match was observed.

Applicability of Quasi-3D Blade Design Methods to Profile Shape Optimizaton of Turbine Blades

2013 ◽  
Author(s):  
Tobias Gezork ◽  
Stefan Völker
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Optimization Methods ◽  
Optimization Strategy ◽  
Gas Turbine Blades ◽  
Profile Shape ◽  
Loss Coefficients ◽  
Physical Effects ◽  
Turbine Airfoils ◽  
Profile Loss

The performance of gas turbine airfoils is continually improved by creating advanced aerodynamic and thermal designs. Optimization methods are used to handle the increasing complexity of such a design. However, optimization is expensive when performed based on 3D CFD calculations. Therefore, an optimization strategy based on simpler, less expensive analysis methods is desirable. Oftentimes, a so-called quasi-3D (Q3D) approach is used, where 2D calculations are carried out on multiple, radially stacked meridional blade sections. This paper investigates the applicability of such an approach for optimization with regard to blade profile loss. Obviously, certain physical effects are neglected using this approach, leading to errors in the predicted blade performance. Still, optimization based on Q3D calculations might be possible if the error is consistent, i.e. not random. For this purpose, a design of experiment (DOE) was carried out to compare and correlate loss predictions from Q3D calculations and high-fidelity 3D CFD calculations for gas turbine blades. It is shown that the total pressure loss coefficients found with both the Q3D and 3D calculations correlate well (75–90%) to warrant the use of a Q3D method for profile shape optimization. Subsequently, an optimization is performed to demonstrate the applicability of the method.

Influence of Loading Distribution on the Off-Design Performance of High-Pressure Turbine Blades

2006 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Design Flow ◽  
Superior Performance ◽  
High Pressure Turbine ◽  
Design Performance ◽  
Mach Numbers ◽  
Exit Mach Number

Linear cascade measurements for the aerodynamic performance of a family of three transonic, high-pressure (HP) turbine blades have been presented previously by the authors. The airfoils were designed for the same inlet and outlet velocity triangles but varied in their loading distributions. The previous papers presented results for the design incidence at various exit Mach numbers, and for off-design incidence at the design exit Mach number of 1.05. Results from the earlier studies indicated that by shifting the loading towards the rear of the airfoil an improvement in the profile loss performance of the order of 20% could be obtained near the design Mach number at design incidence. Measurements performed at off-design incidence, but still at the design Mach number, showed that the superior performance of the aft-loaded blade extended over a range of incidence from about −5.0° to +5.0° relative to the design value. For the current study, additional measurements were performed at off-design Mach numbers from about 0.5 to 1.3 and for incidence values of −10.0°, +5.0° and + 10.0° relative to design. The corresponding Reynolds numbers, based on outlet velocity and true chord, varied from roughly 4 × 105 to 10 × 105. The measurements included midspan losses, blade loading distributions and base pressures. In addition, two-dimensional Navier-Stokes computations of the flow were performed to help in the interpretation of the experimental results. The results show that the superior loss performance of the aft-loaded profile, observed at design Mach number and low values of off-design incidence, does not extend readily to off-design Mach numbers and larger values of incidence. In fact, the measured midspan loss performance for the aft-loaded blade was found to be inferior to, or at best equal to, that of the baseline, mid-loaded airfoil at most combinations of off-design Mach number and incidence. However, based on the observations made at design and off-design flow conditions, it appears that aft-loading can be a viable design philosophy to employ in order to reduce the losses within a blade row provided the rearward deceleration is carefully limited. The loss performance of the front-loaded blade is inferior or at best equal to that of the other two blades for all operating conditions. As such, it appears that there is no advantage to front loading the airfoil for transonic high-pressure turbine blades. The results also provide a significant addition to the data available in the open literature on the off-design performance of transonic HP turbine airfoils.

Influence of Loading Distribution on the Off-Design Performance of High-Pressure Turbine Blades

2006 ◽  
Vol 129 (3) ◽  
pp. 563-571 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Operating Conditions ◽  
Design Flow ◽  
Superior Performance ◽  
Navier Stokes ◽  
Mach Numbers ◽  
Exit Mach Number

Linear cascade measurements for the aerodynamic performance of a family of three transonic, high-pressure (HP) turbine blades have been presented previously by the authors. The airfoils were designed for the same inlet and outlet velocity triangles but varied in their loading distributions. The previous papers presented results for the design incidence at various exit Mach numbers, and for off-design incidence at the design exit Mach number of 1.05. Results from the earlier studies indicated that by shifting the loading towards the rear of the airfoil an improvement in the profile loss performance of the order of 20% could be obtained near the design Mach number at design incidence. Measurements performed at off-design incidence, but still at the design Mach number, showed that the superior performance of the aft-loaded blade extended over a range of incidence from about −5.0deg to +5.0deg relative to the design value. For the current study, additional measurements were performed at off-design Mach numbers from about 0.5 to 1.3 and for incidence values of −10.0deg, +5.0deg, and +10.0deg relative to design. The corresponding Reynolds numbers, based on outlet velocity and true chord, varied from roughly 4×105 to 10×105. The measurements included midspan losses, blade loading distributions, and base pressures. In addition, two-dimensional Navier–Stokes computations of the flow were performed to help in the interpretation of the experimental results. The results show that the superior loss performance of the aft-loaded profile, observed at design Mach number and low values of off-design incidence, does not extend readily to off-design Mach numbers and larger values of incidence. In fact, the measured midspan loss performance for the aft-loaded blade was found to be inferior to, or at best equal to, that of the baseline, midloaded airfoil at most combinations of off-design Mach number and incidence. However, based on the observations made at design and off-design flow conditions, it appears that aft-loading can be a viable design philosophy to employ in order to reduce the losses within a blade row provided the rearward deceleration is carefully limited. The loss performance of the front-loaded blade is inferior or at best equal to that of the other two blades for all operating conditions.

UDIMET L-605

Alloy Digest ◽  
2004 ◽  
Vol 53 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Gas Turbine ◽  
Oxidation Resistance ◽  
Turbine Blades ◽  
Heat Treating ◽  
Gas Turbine Blades ◽  
Temperature Performance

Abstract Udimet L-605 is a high-temperature aerospace alloy with excellent strength and oxidation resistance. It is used in applications such as gas turbine blades and combustion area parts. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: CO-109. Producer or source: Special Metals Corporation.

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