scholarly journals Effects of Periodic Wake Passing Upon Aerodynamic Loss of a Turbine Cascade: Part I — Measurements of Wake-Affected Cascade Loss by Use of a Pneumatic Probe

1999 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Nobuaki Tetsuka ◽  
Tadashi Tanuma
Keyword(s):  
Turbine Cascade ◽  
Flow Angle ◽  
Linear Cascade ◽  
Local Loss ◽  
Aerodynamic Loss ◽  
Free Stream Turbulence ◽  
Pressure Distributions ◽  
Wake Turbulence ◽  
Wake Passing ◽  
Profile Loss

This paper reports on an experimental investigation of aerodynamic loss of a low-speed linear turbine cascade which is subjected to periodic wakes shed from moving bars of the wake generator. In this case, parameters related to the wake, such as wake passing frequency (wake Strouhal number) or wake turbulence characteristics, are varied to see how these wake-related parameters affect the local loss distribution or mass-averaged loss coefficient of the turbine cascade. Free-stream turbulence intensity is changed by use of a turbulence grid. In Part I of this paper a focus is placed on the measurements by use of a pneumatic five-hole yawmeter, which provides time-averaged stagnation pressure distributions downstream of the moving bars as well as of the turbine cascade. Spanwise distributions of wake-affected exit flow angle are also measured. From this study it is found that the wake passing greatly affects not only the profile loss but secondary loss of the linear cascade. Noticeable change in exit flow angle is also identified.

scholarly journals Experimental and Numerical Investigations of Wake Passing Effects Upon Aerodynamic Performance of a LP Turbine Linear Cascade With Variable Solidity

2006 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Kazutoyo Yamada ◽  
Takahiro Ono ◽  
Ken-ichi Segawa ◽  
Hiroshi Hamazaki ◽  
...  
Keyword(s):  
Separation Bubble ◽  
Probe Measurement ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Linear Cascade ◽  
Aerodynamic Loss ◽  
Wire Probe ◽  
Numerical Studies ◽  
Lp Turbine ◽  
Wake Passing

This paper deals with experimental and numerical studies on the flow field around a low-pressure linear turbine cascade whose solidity is changeable. The purpose of them is to clarify the effect of incoming wakes upon the aerodynamic loss of the cascade that is accompanied with separation on the airfoil suction surface, in particular for low Reynolds number conditions and/or low solidity conditions. Cylindrical bars on the timing belts work as wake generator to emulate wakes that impact the cascade. Pneumatic probe measurement is made to obtain total pressure loss distributions downstream of the cascade. Hot-wire probe measurement is also conducted over the airfoil suction surface. Besides, LES-based numerical simulation is executed to deepen the understanding of the interaction of the incoming wakes with the boundary layer containing separation bubble.

scholarly journals A linear cascade tunnel for flow investigations of steam turbine rotor tip blades in subsonic nucleating flows

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Vital Kumar Yadav Pillala ◽  
B. V. S. S. S. Prasad ◽  
N. Sitaram ◽  
M. Mahendran ◽  
Debasish Biswas ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Turbine Rotor ◽  
Turbine Cascade ◽  
Flow Measurements ◽  
Linear Cascade ◽  
Dry Air ◽  
Steam Turbine Rotor ◽  
Pressure Distributions ◽  
Working Medium ◽  
Exit Mach Number

AbstractThe paper presents details of a unique experimental facility along with necessary accessories and instrumentation for testing steam turbine cascade blades in wet and nucleating steam. A steam turbine rotor tip cascade is chosen for flow investigations. Cascade inlet flow measurements show uniform conditions with dry air and steam and dry air mixture of different ratios. Exit flow surveys indicate that excellent flow periodicity is obtained. Blade surface static pressure and exit total pressure distributions are also presented with dry air and with steam and dry air mixture of different ratios as the working medium at an exit Mach number of 0.52.

scholarly journals Effects of Periodic Wake Passing Upon Aerodynamic Loss of a Turbine Cascade: Part II — Time-Resolved Flow Field and Wake Decay Process Through the Cascade

1999 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Nobuaki Tetsuka ◽  
Tadashi Tanuma
Keyword(s):  
Flow Field ◽  
Suction Side ◽  
Fast Response ◽  
Decay Process ◽  
Pressure Probe ◽  
Turbine Cascade ◽  
Time Resolved ◽  
Aerodynamic Loss ◽  
Custom Made ◽  
Wake Passing

This paper, Part II of the study on wake-passing effect upon the aerodynamic performance of the turbine cascade, demonstrates the detailed measurements of the time-varying flow field downstream of the turbine cascade as well as of the moving bars. The experiment employs a single hot-wire probe to measure pitchwise distributions of the ensemble-averaged velocity at the blade midspan. The resultant data consequently provide clear images of the incident bar wakes that are bowed and directed to the suction side of the blade wake. A custom-made total pressure probe, instrumented with a miniature fast-response pressure transducer, are also adopted to understand time-resolved feature of the wake-affected stagnation pressure fields downstream of the cascade. Furthermore, a decay process of the bar wake through the test cascade is examined in detail, which serves for the discussion related to wake recovery and its impact on the stage loss.

scholarly journals Mach Number Effects on Secondary Flow Development Downstream of a Turbine Cascade

1989 ◽  
Author(s):  
Antonio Perdichizzi
Keyword(s):  
Mach Number ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Expansion Ratio ◽  
Turbine Cascade ◽  
Low Velocity ◽  
Flow Angle ◽  
Local Loss ◽  
Flow Development ◽  
Wide Range

The results of an investigation of the three-dimensional flow downstream of a transonic turbine cascade are presented. The investigation was carried out for a wide range of Mach numbers, extending from M2is = 0.2 up to 1.55. Measurements were made in five planes at different axial locations downstream of the trailing edge (covering more than one chord length), by using a miniaturized five hole probe especially designed for transonic flows. The results are presented in terms of local loss coefficient, vorticity and secondary velocity plots; these plots give a detailed picture of the secondary flow development downstream of the cascade and show how flow compressibility influences the vortex configuration. As Mach number increases, the passage vortex is found to migrate towards the endwall and secondary flow effects are more confined in the endwall region. The pitchwise mass averaged loss and flow angle distributions along the blade height appear to be affected by the expansion ratio; at high Mach number both underturning and overturning angles are found to be smaller than in low velocity flows. Overall losses, vorticity and secondary kinetic energy versus Mach number are also presented and discussed.

scholarly journals Nonaxisymmetric Turbine End Wall Design: Part II—Experimental Validation

1999 ◽  
Vol 122 (2) ◽  
pp. 286-293 ◽  
Author(s):  
J. C. Hartland ◽  
D. G. Gregory-Smith ◽  
N. W. Harvey ◽  
M. G. Rose
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Design System ◽  
Flow Angle ◽  
Linear Cascade ◽  
Pressure Distributions ◽  
Turbine Performance ◽  
Passage Vortex ◽  
Blade Row ◽  
End Wall

The Durham Linear Cascade has been redesigned with the nonaxisymmetric profiled end wall described in the first part of this paper, with the aim of reducing the effects of secondary flow. The design intent was to reduce the passage vortex strength and to produce a more uniform exit flow angle profile in the radial direction with less overturning at the wall. The new end wall has been tested in the linear cascade and a comprehensive set of measurements taken. These include traverses of the flow field at a number of axial planes and surface static pressure distributions on the end wall. Detailed comparisons have been made with the CFD design predictions, and also for the results with a planar end wall. In this way an improved understanding of the effects of end wall profiling has been obtained. The experimental results generally agree with the design predictions, showing a reduction in the strength of the secondary flow at the exit and a more uniform flow angle profile. In a turbine stage these effects would be expected to improve the performance of any downstream blade row. There is also a reduction in the overall loss, which was not given by the CFD design predictions. Areas where there are discrepancies between the CFD calculations and measurement are likely to be due to the turbulence model used. Conclusions for how the three-dimensional linear design system should be used to define end wall geometries for improved turbine performance are presented. [S0889-504X(00)01002-3]

Profile Loss Correlations Accounting for Turbine Disk Inclination

2014 ◽  
Vol 529 ◽  
pp. 159-163
Author(s):  
Zhen Wei Yuan ◽  
Jun Zhang ◽  
Dong Shuai Zhu
Keyword(s):  
State Of The Art ◽  
Incidence Angle ◽  
Turbine Disk ◽  
Tip Clearance ◽  
Turbine Cascade ◽  
Flow Angle ◽  
Profile Losses ◽  
Art Works ◽  
Design Value ◽  
Profile Loss

Incidence can significantly affect turbine cascade aerodynamic losses, including profile, secondary and tip-clearance losses. In previous works, correlations for these losses were developed on a convention that the whole cascade has a universal incidence angle. But in reality, there exist exceptional situations when a turbine disk is inclined to its design position. In such cases, the incidence varies with the location of blade on the circumference, leading to loss deviation from its design value. The present paper is motivated to work out new correlations for the profile losses with turbine disk inclinations and examine the effects of turbine disk inclination. Based on the state-of-the-art works, new correlations are developed to take into account the incidence variation by redefining the inlet flow angle in terms of turbine disk inclination angle and location angle of blade on turbine disk circumference. The effects of turbine disk inclination on profile losses were examined through numerical simulations. It is concluded that the turbine disk inclination has considerable influences on the profile losses of turbine cascade.

Spanwise Penetration Depth with Turbine Disk Inclination

2014 ◽  
Vol 945-949 ◽  
pp. 887-891
Author(s):  
Zhen Wei Yuan ◽  
Jun Zhang ◽  
Dong Shuai Zhu
Keyword(s):  
Numerical Simulations ◽  
Penetration Depth ◽  
Turbine Disk ◽  
Turbine Cascade ◽  
Inlet Flow ◽  
Flow Angle ◽  
Profile Loss

Spanwise penetration depth as a new correlating parameter was introduced in the cascade profile loss correlation of a new loss breakdown scheme for turbine cascade reported in the literature. For the case of an inclined turbine disk, when a turbine disk is inclined to its design position, the blade incidence or inlet flow angle varies with the position of blade on the turbine disk circumference, leading to the variation of spanwise penetration depth. To examine the influences of turbine disk inclination on the spanwise penetration depth, new correlations were developed and numerical simulations were performed with MATLAB. The role that turbine disk inclination plays in the spanwise penetration depth is manifested in a modified inlet flow angle expression on account of turbine disk inclination. It is concluded that the turbine disk inclination has considerable influences on the spanwise penetration depth in the turbine cascade passage.

Endwall Flow/Loss Mechanisms in a Linear Turbine Cascade With Blade Tip Clearance

1989 ◽  
Vol 111 (3) ◽  
pp. 264-275 ◽  
Author(s):  
A. Yamamoto
Keyword(s):  
Three Dimensional ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Turbine Cascade ◽  
Flow Angle ◽  
Pressure Distributions ◽  
Flow Loss ◽  
Blade Tip ◽  
Flow Vectors ◽  
Blade Tip Clearance

This paper discusses the mechanisms of three-dimensional flows and of the associated losses occurring near the tip endwall region of a linear turbine cascade with tip clearance. The clearance gap sizes and the cascade incidences were chosen as the most important variables affecting the mechanisms. Flows close to the endwall and inside the clearance were surveyed in great detail using a micro five-hole pitot tube of 0.6 mm head size. The results gave very detailed information on the mechanisms, such as leakage flow vectors and pressure distributions throughout the clearance. Interaction of leakage flow with the endwall flow and their associated separation lines, effects of gap size and inlet flow angle on loss generation, and skewness of the three-dimensional endwall flows are also discussed.

Mach Number Effects on Secondary Flow Development Downstream of a Turbine Cascade

1990 ◽  
Vol 112 (4) ◽  
pp. 643-651 ◽  
Author(s):  
A. Perdichizzi
Keyword(s):  
Mach Number ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Expansion Ratio ◽  
Turbine Cascade ◽  
Low Velocity ◽  
Flow Angle ◽  
Local Loss ◽  
Flow Development ◽  
Wide Range

The results of an investigation of the three-dimensional flow downstream of a transonic turbine cascade are presented. The investigation was carried out for a wide range of Mach numbers, extending from M2is = 0.2 up to 1.55. Measurements were made in five planes at different axial locations downstream of the trailing edge (covering more than one chord length), by using a miniaturized five-hole probe especially designed for transonic flows. The results are presented in terms of local loss coefficient, vorticity, and secondary velocity plots; these plots give a detailed picture of the secondary flow development downstream of the cascade and show how flow compressibility influences the vortex configuration. As Mach number increases, the passage vortex is found to migrate toward the endwall and secondary flow effects are more confined in the endwall region. The pitchwise mass averaged loss and flow angle distributions along the blade height appear to be affected by the expansion ratio; at high Mach number both underturning and overturning angles are found to be smaller than in low velocity flows. Overall losses, vorticity, and secondary kinetic energy versus Mach number are also presented and discussed.

scholarly journals Non-Axisymmetric Turbine End Wall Design: Part II — Experimental Validation

1999 ◽  
Author(s):  
J. C. Hartland ◽  
D. G. Gregory-Smith ◽  
N. W. Harvey ◽  
M. G. Rose
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Design System ◽  
Flow Angle ◽  
Linear Cascade ◽  
Pressure Distributions ◽  
Turbine Performance ◽  
Passage Vortex ◽  
Blade Row ◽  
End Wall

The Durham Linear Cascade has been redesigned with the non-axisymmetric profiled end wall described in the first part of this paper, with the aim of reducing the effects of secondary flow. The design intent was to reduce the passage vortex strength and to produce a more uniform exit flow angle profile in the radial direction with less over turning at the wall. The new end wall has been tested in the linear cascade and a comprehensive set of measurements taken. These include traverses of the flow field at a number of axial planes and surface static pressure distributions on the end wall. Detailed comparisons have been made with the CFD design predictions, and also for the results with a planar end wall. In this way an improved understanding of the effects of end wall profiling has been obtained. The experimental results generally agree with the design predictions, showing a reduction in the strength of the secondary flow at the exit and a more uniform flow angle profile. In a turbine stage these effects would be expected to improve the performance of any downstream blade row. There is also a reduction in the overall loss, which was not given by the CFD design predictions. Areas where there are discrepancies between the CFD calculations and measurement are likely to be due to the turbulence model used. Conclusions for how the three-dimensional linear design system should be used to define end wall geometries for improved turbine performance are presented.

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