Forces and Surface Pressure on a Blade Moving in Front of the Admission Region

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Soo-Yong Cho ◽  
Chong-Hyun Cho ◽  
Kook-Young Ahn ◽  
Young-Cheol Kim
Keyword(s):  
Cross Section ◽  
Performance Test ◽  
Nozzle Flow ◽  
Flow Angle ◽  
Linear Cascade ◽  
Blade Row ◽  
Partial Admission ◽  
Additional Losses ◽  
Rotational Direction ◽  
Admission Region

The partial admission technique is widely used to control the output power of turbines. In some cases, it has more merits than full admission. However, additional losses, such as expansion, mixing, or pumping, are generated in partial admission as compared with full admission. Thus, an experiment was conducted in a linear cascade apparatus having a partial admission region in order to investigate the effect of partial admission on a blade row. The admission region was formed by a spouting nozzle installed at the inlet of the linear cascade apparatus. Its cross section was rectangular and its size is 200×200 mm2. The tested blade was axial-type and its chord was 200 mm. Nineteen identical blades were applied to the linear cascade for the partial admission experiment. The blades moved along the rotational direction in front of the admission region, and then operating forces and surface pressures on the blades were measured at the steady state. The experiment was conducted at a Reynolds number of 3×105 based on the chord. The nozzle flow angle was set to 65 deg with a solidity of 1.38 for performance test at the design point. In addition, another two different solidities of 1.25 and 1.67 were applied. From the experimental results, when the solidity was decreased, the maximum rotational force increased but the maximum axial force decreased.

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]

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.

Effects of the Main Gas Path Pressure Field on Rim Seal Flows in a Stationary Linear Cascade

2015 ◽  
Author(s):  
Jeffrey Gibson ◽  
Karen Thole ◽  
Jesse Christophel ◽  
Curtis Memory
Keyword(s):  
Bluff Body ◽  
Pressure Field ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Baseline Design ◽  
Linear Cascade ◽  
Blade Row ◽  
High Degree ◽  
Effectiveness Data ◽  
Computational Predictions

Rim seals in the turbine section of gas turbine engines aim to reduce the amount of purge air required to prevent the ingress of hot mainstream gas into the under-platform space. A stationary, linear cascade was designed, built, and benchmarked to study the effect of the interaction between the pressure fields from an upstream vane row and downstream blade row on hot gas ingress for engine-realistic rim seal geometries. The pressure field of the downstream blade row was modeled using a bluff body designed to produce the pressure distortion of a moving blade. Sealing effectiveness data for the baseline seal indicated that there was little to no ingress with a purge rate greater than 1% of the main gas path flow. Adiabatic endwall effectiveness data downstream in the trench between the vane and blade showed a high degree of mixing. Extending the seal feature associated with the vane endwall indicated better sealing than the baseline design. Steady computational predictions were found to overpredict the sealing effectiveness due to underpredicted mixing in the trench.

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.

Research on the Anti-Vibration Technology of Large Cross-Section Conductor

2013 ◽  
Vol 457-458 ◽  
pp. 522-526
Author(s):  
Jun Zhang ◽  
Kuan Jun Zhu ◽  
Zhen Liu ◽  
Xue Ping Zhan
Keyword(s):  
Cross Section ◽  
Performance Test ◽  
Power Transmission ◽  
Normal Operation ◽  
Large Cross Section ◽  
Element Analysis ◽  
Test Analysis ◽  
Vibration Effect ◽  
The Finite Element Analysis ◽  
Vibration Technology

The conductor is an important part of the process of power transmission. Keep conductor to be normal operation is an important link of power transmission. In practice, Due to the influence of many weather environments, such as wind, temperature, rain and snow, the conductor often appear ice disaster, dance and other disasters; therefore, the anti-vibration technology of conductor is an urgent need to develop. This paper masters the performance of damper by carrying out a great deal of performance test analysis, such as self-damping, the power of damper, anti-vibration effect. At the same time, this paper understands the effect of spacer arrangement on the sub span oscillation, through the finite element analysis and lingo program of nonlinear programming, laying the foundation for studying anti-vibration technology for large cross-section conductor.

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

Control of Shroud Leakage Loss by Reducing Circumferential Mixing

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Budimir Rosic ◽  
John D. Denton
Keyword(s):  
Significant Proportion ◽  
Tangential Velocity ◽  
Secondary Flows ◽  
Main Stream ◽  
Leakage Flow ◽  
Flow Angle ◽  
Blade Row ◽  
Stator Blade ◽  
The Difference ◽  
Mixing Losses

Shroud leakage flow undergoes little change in the tangential velocity as it passes over the shroud. Mixing due to the difference in tangential velocity between the main stream flow and the leakage flow creates a significant proportion of the total loss associated with shroud leakage flow. The unturned leakage flow also causes negative incidence and intensifies the secondary flows in the downstream blade row. This paper describes the experimental results of a concept to turn the rotor shroud leakage flow in the direction of the main blade passage flow in order to reduce the aerodynamic mixing losses. A three-stage air model turbine with low aspect ratio blading was used in this study. A series of different stationary turning vane geometries placed into the rotor shroud exit cavity downstream of each rotor blade row was tested. A significant improvement in flow angle and loss in the downstream stator blade rows was measured together with an increase in turbine brake efficiency of 0.4 %.

scholarly journals Effects of Transient Heat Transfer on Compressor Stability

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
A. Kiss ◽  
Z. Spakovszky
Keyword(s):  
Heat Transfer ◽  
Pressure Ratio ◽  
Strong Dependence ◽  
Transient Heat Transfer ◽  
Compressor Blades ◽  
Flow Angle ◽  
Stall Margin ◽  
Point Reduction ◽  
Angle Deviation ◽  
Blade Row

The effects of heat transfer between the compressor structure and the primary gas path flow on compressor stability are investigated during hot engine re-acceleration transients. A mean line analysis of an advanced, high-pressure ratio compressor is extended to include the effects of heat transfer on both stage matching and blade row flow angle deviation. A lumped capacitance model is used to compute the heat transfer of the compressor blades, hub, and casing to the primary gas path. The inputs to the compressor model with heat transfer are based on a combination of full engine data, compressor test rig measurements, and detailed heat transfer computations. Nonadiabatic transient calculations show a 8.0 point reduction in stall margin from the adiabatic case, with heat transfer predominantly altering the transient stall line. 3.4 points of the total stall margin reduction are attributed to the effect of heat transfer on blade row deviation, with the remainder attributed to stage rematching. Heat transfer increases loading in the front stages and destabilizes the front block. Sensitivity studies show a strong dependence of stall margin to heat transfer magnitude and flow angle deviation at low speed, due to the effects of compressibility. Computations for the same transient using current cycle models with bulk heat transfer effects only capture 1.2 points of the 8.0 point stall margin reduction. Based on this new capability, opportunities exist early in the design process to address potential stability issues due to transient heat transfer.

scholarly journals A Test Facility for the Investigation of Steady and Unsteady Transonic Flows in Annular Cascades

1983 ◽  
Author(s):  
Albin Bölcs
Keyword(s):  
Test Facility ◽  
Vehicle Design ◽  
Flow Conditions ◽  
Axial Section ◽  
Flow Angle ◽  
Transonic Flows ◽  
Linear Cascade ◽  
Boundary Layer Suction ◽  
Aerodynamic Test ◽  
Downstream Flow

A unique non-rotating aerodynamic test facility is presented. It is designed for steady and unsteady transonic flow investigations in annular cascades. The fundamental advantage of this vehicle design, compared to a linear cascade facility, is the absence of boundary disturbances in the cascade and the self-adjustment of the flow periodicity. The downstream flow conditions can therefore be adjusted by the backpressure. The nozzle consists of a radial-axial section, in which spiral axisymetric flow is generated. With the adjustment of the total pressure and swirl angles in two separate distributors, a continuous variation of Mach number between 0<M<1,4 and flow angles between 12°<β<70° (from tangential) can be obtained. Further regulation of the flow quantities in the two separate distributors and boundary layer suction permits a continuous spanwise variation of the velocity and flow angle in the test section.

Comparison of Steady and Unsteady Secondary Flows in a Turbine Stator Cascade

1989 ◽  
Author(s):  
Gregory J. Hebert ◽  
William G. Tiederman
Keyword(s):  
Secondary Flows ◽  
Rotor Blades ◽  
Velocity Measurements ◽  
Flow Loop ◽  
Suction Surface ◽  
Linear Cascade ◽  
Turbine Stator ◽  
Passage Vortex ◽  
Blade Row ◽  
Secondary Flow Structure

The effect of periodic rotor wakes on the secondary flow structure in a turbine stator cascade was investigated. A mechanism simulated the wakes shed from rotor blades bypassing cylindrical rods across the inlet to a linear cascade installed in a recirculating water flow loop. Velocity measurements showed a passage vortex, similar to that seen in steady flow, during the time associated with undisturbed fluid. However, as the rotor wake passed through the blade row, a large crossflow toward the suction surface was observed in the midspan region. This caused the development of two large areas of circulation between the midspan and endwall regions, significantly distorting and weakening the passage vortices.

Sign in / Sign up

Export Citation Format

Share Document