Aerodynamic Performance of a Transonic Turbine Cascade at Off-Design Conditions

2000 ◽  
Author(s):  
D. B. M. Jouini ◽  
S. A. Sjolander ◽  
S. H. Moustapha
Keyword(s):  
Axial Velocity ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Base Pressure ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Profile Losses ◽  
Transonic Turbine ◽  
Mach Numbers

The paper presents detailed measurements of the midspan aerodynamic performance of a transonic turbine cascade at off-design conditions. The measurements were conducted for exit Mach numbers ranging from 0.5 to 1.2 and for Reynolds numbers from 4×105 to 106. The profile losses were measured for incidence values of +14.5°, +10°, +4.5°, 0°, and −10° relative to design. To aid in understanding the loss behaviour and to provide other insights into the flow physics, measurements of blade loading, exit flow angles, trailing-edge base pressures, and the Axial Velocity Density Ratio (AVDR) were also made. It was found that the profile losses at transonic Mach numbers can be closely related to the base pressure behaviour. The losses were also affected by the AVDR.

Aerodynamic Performance of a Transonic Turbine Cascade at Off-Design Conditions

2000 ◽  
Vol 123 (3) ◽  
pp. 510-518 ◽  
Author(s):  
D. B. M. Jouini ◽  
S. A. Sjolander ◽  
S. H. Moustapha
Keyword(s):  
Axial Velocity ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Base Pressure ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Profile Losses ◽  
Transonic Turbine ◽  
Mach Numbers

The paper presents detailed measurements of the midspan aerodynamic performance of a transonic turbine cascade at off-design conditions. The measurements were conducted for exit Mach numbers ranging from 0.5 to 1.2, and for Reynolds numbers from 4×105 to 106. The profile losses were measured for incidence values of +14.5 deg, +10 deg, +4.5 deg, 0 deg, and −10 deg relative to design. To aid in understanding the loss behavior and to provide other insights into the flow physics, measurements of blade loading, exit flow angles, trailing-edge base pressures, and the axial velocity density ratio (AVDR) were also made. It was found that the profile losses at transonic Mach numbers can be closely related to the base pressure behavior. The losses were also affected by the AVDR.

Effects of Unsteady Wakes on the Secondary Flows in the Linear T106 Turbine Cascade

2013 ◽  
Author(s):  
Roberto Ciorciari ◽  
Ilker Kirik ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
High Pressure ◽  
Aerodynamic Performance ◽  
High Flow ◽  
Secondary Flows ◽  
Experimental Results ◽  
Pressure Gradients ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Relative Differences

In modern low pressure turbines the efforts to increase aerodynamic blade loading by increasing blade pitch and optimising midspan performance in order to reduce weight and complexity can produce increased losses in the endwall region. Airfoils of high flow turning and high pressure gradients between the blades generate strong secondary flows which impair the global aerodynamic performance of the blades. In addition, the unsteady incoming wakes take influence on transition phenomena on the blade surfaces and the inlet boundary layer, and consequently affect the development and the evolution of the secondary flows. In this paper the T106 cascade is used to identify the effect of unsteady wakes on the development of secondary flows in a turbine cascade. Numerical and experimental results are compared at different flux coefficients and Strouhal numbers, the relative differences and similarities are analysed.

Simulation and Validation of Mach Number Effects on Secondary Flow in a Transonic Turbine Cascade Using a Multigrid, k–ε Solver

1998 ◽  
Vol 120 (2) ◽  
pp. 285-297 ◽  
Author(s):  
M. Koiro ◽  
B. Lakshminarayana
Keyword(s):  
Secondary Flow ◽  
Incompressible Flows ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Test Case ◽  
Turbine Cascade ◽  
Efficient Manner ◽  
Wall Boundary Layer ◽  
Transonic Turbine ◽  
Mach Numbers

An existing three-dimensional Navier–Stokes flow solver with an explicit Runge–Kutta algorithm and a low-Reynolds-number k–ε turbulence model has been modified in order to simulate turbomachinery flows in a more efficient manner. The solver has been made to converge more rapidly through use of the multigrid technique. Stability problems associated with the use of multigrid in conjunction with two-equation turbulence models are addressed and techniques to alleviate instability are investigated. Validation for the new code was performed with a transonic turbine cascade tested by Perdichizzi. In the fully three-dimensional turbulent cascade, real convergence (i.e., CPU time) was improved nearly two times the original code. Robustness was enhanced with the full multigrid initialization procedure. The same test case was then used to perform a series of simulations that investigated the effect of different exit Mach numbers on secondary flow features. This permitted an in-depth study into the mechanisms of secondary flow formation and secondary losses at high Mach numbers. In this cascade, it was found that secondary losses and secondary flow deviation, which are fairly constant in incompressible flows with similar geometries, underwent a large reduction in the compressible flow range. The structure of the trailing edge shock system and the reduced end wall boundary layer at supersonic exit conditions were shown to be very significant in reducing the amount of secondary flow and losses.

Effects of Trailing Edge Thickness and Blade Loading Distribution on the Aerodynamic Performance of Simulated CMC Turbine Blades

2020 ◽  
Author(s):  
Paul W. Giel ◽  
Vikram Shyam ◽  
Paht Juangphanich ◽  
John P. Clark
Keyword(s):  
Reynolds Number ◽  
Turbulence Intensity ◽  
Large Scale ◽  
Turbine Blades ◽  
Ceramic Matrix Composite ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Trailing Edge ◽  
Blade Loading ◽  
Exit Mach Number

Abstract The aerodynamic performance of three blade sets that represent the geometric manufacturing constraints of Ceramic Matrix Composite (CMC) blades was measured experimentally in a large-scale transonic turbine blade cascade. The trailing edge thicknesses of CMC blades are anticipated to be significantly larger than those of current state-of-the-art metallic blades. The blades tested in the current study had trailing edge thicknesses of 5%, 7%, and 9% relative to the blade axial chord. The three blade sets were designed with matching throat dimensions, so the blade loading distributions were varied to retain similar overall loading levels. Data were acquired at four Reynolds numbers, covering a factor of six range. All data were acquired at the design isentropic exit Mach number of 0.74. Measurements include blade loading and five-hole probe surveys at two downstream stations. The effects of inlet turbulence intensity were also quantified. Total pressure loss data were integrated to determine overall loss levels for each of the three measured blade passages. Excellent periodicity was noted. For low inlet turbulence levels, losses were surprisingly lower for the thickest trailing edge at low Reynolds numbers, but were highest at the maximum Reynolds number. In general, losses were found to scale well with Reynolds number, although front loading was found to significantly reduce the sensitivity of loss to Reynolds number. For high inlet turbulence intensity, losses were found to scale with trailing edge thickness as expected, and the Reynolds number sensitivity was reduced for all three blade sets. Loss levels at the highest Reynolds number were comparable at low and high inlet turbulence intensity levels.

Aerodynamic Performance of a Family of Three High Pressure Transonic Turbine Blades at Off-Design Incidence

2005 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Blade Loading ◽  
Design Values ◽  
Outlet Flow ◽  
Exit Mach Number

Linear cascade measurements for the aerodynamic performance of three transonic High Pressure (HP) turbine blades have been presented previously by Corriveau and Sjolander [1] [2] for the design incidence. The airfoils were designed for the same inlet and outlet velocity triangles but varied in their loading distributions. 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 of 1.05. The measurements have been extended to off-design incidence to investigate the effects of incidence on the performance of HP turbine blades having differing loading distributions. The additional measurements were performed for incidence values of −10.0°, +5.0°, and +10.0° relative to the design incidence. In addition, two-dimensional Navier-Stokes numerical simulations of the cascade flow were performed in order to help in the interpretation of the experimental results. The exit Mach number was kept at the design value of 1.05. The corresponding Reynolds numbers, based on outlet velocity and true chord, is roughly 10 × 105. The measurements include midspan losses, outlet flow angles, blade loading distributions and base pressures. The results show that the superior loss performance of the aft-loaded profile, observed at design incidence and Mach number, could also be seen for off-design values of incidence ranging from about −5.0° to +5.0°. However, it was found that for incidences greater than about +5.0° the performance of the aft-loaded blade deteriorated rapidly. The front-loaded airfoil showed generally similar performance to that of the baseline mid-loaded airfoil up to an incidence of +5.0°, at which point its performance also deteriorates significantly.

Study on aerodynamic optimal super/transonic turbine cascade and its geometry characteristics

2016 ◽  
Vol 231 (3) ◽  
pp. 435-443 ◽  
Author(s):  
Lucheng Ji ◽  
Jia Yu ◽  
Weiwei Li ◽  
Weilin Yi
Keyword(s):  
Shock Waves ◽  
Adjoint Method ◽  
Numerical Study ◽  
Aerodynamic Performance ◽  
Turbine Cascade ◽  
Negative Effects ◽  
Machine Dynamics ◽  
Optimum Aerodynamic ◽  
Transonic Turbine ◽  
The Relationship

The shock waves are important phenomena in transonic turbines, which cause lots of negative effects on the aerodynamic performance. Much of attention had been paid on reducing the strength of the shock waves via modifying turbine cascade geometry, and it is highly preferred to build experiences on the relationship between the cascade aerodynamic performance and the geometric parameters. The paper presents a numerical study on the aerodynamic optimal transonic turbine cascade and its geometry characteristics. Three typical Russia transonic turbine cascades with different design conditions are selected and optimized using adjoint method at three different back pressures, respectively. Thus, the best geometry parameters for optimum aerodynamic performance can be found. Then the key geometry parameters of optimized cascades are extracted and compared with the original ones. Results show that even the best designs by hands could be less efficient than ones by computer-aided optimizations. Some experiences on how to set the key geometry parameters for a best performance are obtained. The reduced shock profiling is applied to the thermal turbomachinery and machine dynamics transonic turbine by using the adjoint method. The performance of the thermal turbomachinery and machine dynamics transonic turbine was increased significantly.

scholarly journals The Influence of Trailing Edge Ejection on the Base Pressure in Transonic Turbine Cascades

1982 ◽  
Author(s):  
C. H. Sieverding
Keyword(s):  
Turbine Blades ◽  
Density Ratio ◽  
Main Flow ◽  
Coolant Flow ◽  
Base Pressure ◽  
Trailing Edge ◽  
Number Range ◽  
Transonic Turbine ◽  
Turbine Cascades ◽  
Transonic Cascade

This paper summarizes the results of base pressure studies on transonic turbine blades in presence of an ejection of coolant flow from a slot in the trailing edge. The first part of the paper reports on tests carried out on a enlarged model of the overhang section of a typical transonic cascade. This model provides valuable information about the detailed trailing edge pressure distribution and points to an asymmetric evolution of the base pressure on both sides of the slot in presence of a bleed. The second part of the paper presents experimental results from cascade tests covering an outlet Mach number range from M2, is = 0.5 to 1.35. These experiments underline the importance of the coolant flow impact on the base pressure and confirm the asymmetry of the base pressure with respect to the cooling slot. Tests with different coolant flow gases point to the significance of a proper simulation of the density ratio between coolant flow and main flow.

Influence of Loading Distribution on the Performance of Transonic HP Turbine Blades

2003 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
Turbine Blade ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Blade Loading ◽  
Pressure Losses ◽  
Pressure Distributions ◽  
Mach Numbers ◽  
Exit Mach Number ◽  
Transonic Wind Tunnel ◽  
Made In

Midspan measurements were made in a transonic wind tunnel for three HP turbine blade cascades at design incidence. The baseline profile is the midspan section of a HP turbine blade of fairly recent design. It is considered mid-loaded. To gain a better understanding of blade loading limits and the influence of loading distributions, the profile of the baseline airfoil was modified to create two new airfoils having aft-loaded and front-loaded pressure distributions. Tests were performed for exit Mach numbers between 0.6 and 1.2. In addition, measurements were made for an extended range of Reynolds numbers for constant Mach numbers of 0.6, 0.85, 0.95 and 1.05. At the design exit Mach number of 1.05, the aft-loaded airfoil showed a reduction of almost 20% in the total pressure losses compared with the baseline airfoil. However, it was also found that for Mach numbers higher than the design value the performance of the aft-loaded blade deteriorated rapidly. The front-loaded airfoil showed generally inferior performance compared with the baseline airfoil.

Base Pressure Measurements on Elliptic Cones in Supersonic Flow

1967 ◽  
Vol 18 (3) ◽  
pp. 298-307 ◽  
Author(s):  
W. Stahl ◽  
H. Grauer-Carstensen
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Reasonable Agreement ◽  
Flow Theory ◽  
Reynolds Numbers ◽  
Base Flow ◽  
Base Pressure ◽  
Pressure Measurements ◽  
Pressure Coefficients ◽  
Mach Numbers

SummaryAt the Aerodynamische Versuchsanstalt Gottingen (AVA), base pressure measurements were made on five elliptic cones. The ratios of the axes of the ellipses were: 1:12, 1:3, 1:1, 3:1, and 12:1. All the cones had the same volume and the same length. The investigations were carried out for Mach numbers M∞=1·50, 1·73, and 1·98 at angles of incidence between about —2 degrees and about 8 degrees. Reynolds numbers, based on a mean length, lm, varied from 2·5×106 to 3·0×106; the boundary layer approaching the base was turbulent. The base pressure coefficients are given as a function of geometry. Some of the results were compared with the base-flow theory of Korst and reasonable agreement was found.

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