scholarly journals On the Characteristics of Wing with Tip Clearance : Part 3, The Force Acting on a Rectangular Wing of Low Aspect Ratio

1971 ◽  
Vol 14 (76) ◽  
pp. 1077-1087
Author(s):  
Yoshiyuki SUGIYAMA
Keyword(s):  
Aspect Ratio ◽  
Tip Clearance ◽  
Low Aspect Ratio

Aerodynamic Effects of an Unshrouded Low Pressure Turbine on a Low Aspect Ratio Exit Guide Vane

2012 ◽  
Author(s):  
Thorsten Selic ◽  
Davide Lengani ◽  
Andreas Marn ◽  
Franz Heitmeir
Keyword(s):  
Aspect Ratio ◽  
Guide Vane ◽  
Low Pressure ◽  
Tip Clearance ◽  
Pressure Probe ◽  
Model Parameters ◽  
Leakage Flow ◽  
Low Pressure Turbine ◽  
Low Aspect Ratio ◽  
The Impact

This paper presents the effects of an unshrouded low pressure turbine (LPT) onto the following exit guide vane row (EGV). The measurement results were obtained in the subsonic test turbine facility at Graz University of Technology by means of a fast response pressure probe in planes downstream of the rotor as well as oil flow visualisation. The test rig was designed in cooperation with MTU Aero Engines and represents the last 1.5 stages of a commercial aero engine. Considerable efforts were put into the adjustment of all relevant model parameters to reproduce the full scale LPT situation. Different tip clearances were evaluated by means of CFD obtained using a commercial Navier-Stokes code and validated with experimental results. The goal is to evaluate the effect of the varying leakage flow on the flow in the low aspect ratio EGV. Special attention is given to the impact on the development of secondary flows as well as the flow structures downstream of the EGV. The effect of the leakage flow causes a change of the flow structure of the EGV, particularly losses. Considering the largest investigated tip-clearance, the losses increased by 71% when compared to a zero-leakage case.

Influence of Blade Sweep on the Energetic Behavior of Axial Flow Turbomachinery Rotors at Design Flow Rate

2004 ◽  
Author(s):  
Ja´nos Vad ◽  
Ali R. A. Kwedikha ◽  
Helmut Jaberg
Keyword(s):  
Aspect Ratio ◽  
Flow Rate ◽  
Axial Flow ◽  
Pressure Rise ◽  
Design Flow ◽  
Tip Clearance ◽  
Total Efficiency ◽  
Low Aspect Ratio ◽  
Axial Velocity Profile ◽  
Bladed Rotor

Experimental and computational studies were carried out in order to survey the energetic aspects of forward and backward sweep in axial flow rotors of low aspect ratio blading for incompressible flow. It has been pointed out that negative sweep tends to increase the lift, the flow rate and the ideal total pressure rise in the vicinity of the endwalls. Just the opposite tendency was experienced for positive sweep. The local losses were found to develop according to combined effects of sweep near the endwalls, endwall and tip clearance losses, and profile drag influenced by re-arrangement of the axial velocity profile. The forward-swept bladed rotor showed reduced total efficiency compared to the unswept and swept-back bladed rotors. This behavior has been explained on the basis of analysis of flow details. It has been found that the swept bladings of low aspect ratio tend to retain the performance of the unswept datum rotor even in absence of sweep correction.

Experimental and Numerical Study of Stall Flutter in a Transonic Low-Aspect Ratio Fan Blisk

2003 ◽  
Author(s):  
A. J. Sanders ◽  
K. K. Hassan ◽  
D. C. Rabe
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Strain Gages ◽  
Pressure Transducers ◽  
Low Aspect Ratio ◽  
Benchmark Data

Experiments are performed on a modern design transonic shroudless low-aspect ratio fan blisk that experienced both subsonic/transonic and supersonic stall-side flutter. High-response flush mounted miniature pressure transducers are utilized to measure the unsteady aerodynamic loading distribution in the tip region of the fan for both flutter regimes, with strain gages utilized to measure the vibratory response at incipient and deep flutter operating conditions. Numerical simulations are performed and compared with the benchmark data using an unsteady three-dimensional nonlinear viscous computational fluid dynamic (CFD) analysis, with the effects of tip clearance, vibration amplitude, and the number of time steps-per-cycle investigated. The benchmark data are used to guide the validation of the code and establish best practices that ensure accurate flutter predictions.

Investigation of the Aerodynamic Performance of Small Axial Turbines

1973 ◽  
Vol 95 (4) ◽  
pp. 326-332 ◽  
Author(s):  
J. S. Ewen ◽  
F. W. Huber ◽  
J. P. Mitchell
Keyword(s):  
Aspect Ratio ◽  
Tip Clearance ◽  
Low Aspect Ratio ◽  
Turbine Efficiency ◽  
Design Variables ◽  
Paper Cover ◽  
Blade Tip ◽  
Design Velocity ◽  
Axial Turbines ◽  
Cooling Air

This paper describes results of an experimental investigation of small axial turbine performance characteristics. Included are test data on the effects of the following design variables on small turbine aerodynamic efficiency: (a) blade height, (b) vane endwall contouring, (c) blade reaction, (d) blade tip clearance, (e) stage work, and (f) vane and blade airfoil row solidity. In addition, the effects of vane, blade, and disk cooling air injection on turbine efficiency are presented. The turbines evaluated were single stage, low aspect ratio configurations sized for airflows of 8 pps (3.63 kg/sec) or less and designed for inlet temperatures in the 2200-to-2500 deg F (1204-to-1371 deg C) range. The efficiency data presented in the paper cover both design and off-design velocity and pressure ratios. These data illustrate that relatively high efficiencies can be obtained in small, low aspect ratio axial turbines with an optimum design.

An Application of 3-D Viscous Flow Analysis to the Design of a Low-Aspect-Ratio Turbine

1979 ◽  
Author(s):  
H. C. Liu ◽  
T. C. Booth ◽  
W. A. Tall
Keyword(s):  
Aspect Ratio ◽  
Viscous Flow ◽  
Flow Analysis ◽  
Optimization Procedure ◽  
Tip Clearance ◽  
Specific Work ◽  
Turbine Stage ◽  
Gas Generator ◽  
Low Aspect Ratio

Previously reported cascade test results verified and provided a calibration of the 3-D viscous flow analysis. This paper describes the subsequent AFAPL-sponsored technology program in which the 3-D viscous flow computer program was used to optimize the low-aspect-ratio stator of a high-work turbine stage. The optimization procedure, in conjunction with the radial distribution of energy extraction, led to innovative-but-realistic blading for advanced gas generator turbines. A turbine stage was tested with this stator, in conjunction with an appropriate rotor design. The total-to-total design-point efficiency — 92 percent at 1-percent tip clearance — was achieved at 31.83 Btu/lbm specific work. In addition to stage tests, separate stator tests were conducted including a measurement of total pressure loss and stator reaction torque, which provided baseline data to assess interaction effects during stage testing with stator reaction measurements “in vivo.”

A Theory for Rectangular Wings with Small Tip Clearance in a Channel

1973 ◽  
Vol 24 (2) ◽  
pp. 103-119
Author(s):  
Y Sugiyama
Keyword(s):  
Aspect Ratio ◽  
Present Theory ◽  
Uniform Flow ◽  
Tip Clearance ◽  
Low Aspect Ratio ◽  
Simplifying Assumptions ◽  
Low Aspect Ratio Wings

SummaryEquations are derived for the total lift about low aspect ratio wings in an inviscid, incompressible, uniform flow. The analysis extends Bollay’s analysis, which followed the line suggested by Prandtl, and it is shown experimentally that Bollay’s simplifying assumptions can still be applied. Agreement is good between the present theory and the author’s experiment for values of total lift with small tip clearance.

Experimental and Numerical Study of Stall Flutter in a Transonic Low-Aspect Ratio Fan Blisk

2004 ◽  
Vol 126 (1) ◽  
pp. 166-174 ◽  
Author(s):  
A. J. Sanders ◽  
K. K. Hassan ◽  
D. C. Rabe
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Strain Gages ◽  
Pressure Transducers ◽  
Low Aspect Ratio ◽  
Benchmark Data

Experiments are performed on a modern design transonic shroudless low-aspect ratio fan blisk that experienced both subsonic/transonic and supersonic stall-side flutter. High-response flush mounted miniature pressure transducers are utilized to measure the unsteady aerodynamic loading distribution in the tip region of the fan for both flutter regimes, with strain gages utilized to measure the vibratory response at incipient and deep flutter operating conditions. Numerical simulations are performed and compared with the benchmark data using an unsteady three-dimensional nonlinear viscous computational fluid dynamic (CFD) analysis, with the effects of tip clearance, vibration amplitude, and the number of time steps-per-cycle investigated. The benchmark data are used to guide the validation of the code and establish best practices that ensure accurate flutter predictions.

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