scholarly journals Volumetric entropy generation rate associated with tip clearance flow in linear cascade

2021 ◽  
Vol 1081 (1) ◽  
pp. 012045
Author(s):  
Long Bingxiang ◽  
Chen Qin ◽  
Ren Zebin ◽  
Liao Daxiong
Keyword(s):  
Entropy Generation ◽  
Tip Clearance ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Tip Clearance Flow ◽  
Linear Cascade ◽  
Clearance Flow

Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade

2008 ◽  
Author(s):  
Richard Williams ◽  
David Gregory-Smith ◽  
Li He ◽  
Grant Ingram
Keyword(s):  
Gas Turbines ◽  
Tip Clearance ◽  
Computational Techniques ◽  
Tip Clearance Flow ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Controlled Diffusion ◽  
Clearance Flow ◽  
Industrial Gas Turbines ◽  
Tip Clearance Vortex

Large tip clearances typically in the region of six percent exist in the high pressure stages of compressors of industrial gas turbines. Due to the relatively short annulus height and significant blockage, the tip clearance flow accounts for the largest proportion of loss in the HP. Therefore increasing the understanding of such flows will allow for improvements in design of such compressors, increasing efficiency, stability and the operating range. Experimental and computational techniques have been used to increase the physical understanding of the tip clearance flows through varying clearances in a linear cascade of controlled-diffusion blades. This paper shows two unexpected results. Firstly the loss does not increase with clearances greater than 4% and secondly there is an increase of blade loading towards the tip above 2% clearance. It appears that the loss production mechanisms of the pressure driven tip clearance jet do not increase as the clearance is increased to large values. The increase in blade force is attributed to the effect of the strong tip clearance vortex which does not move across the blade passage to the pressure surface, as is often observed for high stagger blading. These results may be significant for the design of HP compressors for industrial gas turbines.

Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Richard Williams ◽  
David Gregory-Smith ◽  
Li He ◽  
Grant Ingram
Keyword(s):  
Gas Turbines ◽  
Tip Clearance ◽  
Computational Techniques ◽  
Tip Clearance Flow ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Controlled Diffusion ◽  
Clearance Flow ◽  
Industrial Gas Turbines ◽  
Tip Clearance Vortex

Large tip clearances typically in the region of 6% exist in the high pressure (HP) stages of compressors of industrial gas turbines. Due to the relatively short annulus height and significant blockage, the tip clearance flow accounts for the largest proportion of loss in the HP. Therefore increasing the understanding of such flows will allow for improvements in design of such compressors, increasing efficiency, stability, and the operating range. Experimental and computational techniques have been used to increase the physical understanding of the tip clearance flows through varying clearances in a linear cascade of controlled-diffusion blades. This paper shows two unexpected results. First the loss does not increase with clearances greater than 4% and second there is an increase in blade loading toward the tip above 2% clearance. It appears that the loss production mechanisms of the pressure driven tip clearance jet do not increase as the clearance is increased to large values. The increase in blade force is attributed to the effect of the strong tip clearance vortex, which does not move across the blade passage to the pressure surface, as is often observed for high stagger blading. These results may be significant for the design of HP compressors for industrial gas turbines.

Endwall Profiling With Tip Clearance Flows

2012 ◽  
Author(s):  
Michael Hilfer ◽  
Grant Ingram ◽  
Simon Hogg
Keyword(s):  
Aspect Ratio ◽  
Design Process ◽  
Experimental Validation ◽  
Tip Clearance ◽  
Design System ◽  
Tip Clearance Flow ◽  
Linear Cascade ◽  
Low Speed ◽  
Clearance Flow

This paper describes the design of a non-axisymmetric profiled endwall with tip clearance flow. Previous designs have assumed that the interaction between the tip clearance flow and the endwall has been negligible and this paper allows this assumption to be tested. A profiled endwall was designed, built and tested in a low speed linear cascade. The design was conducted using the Durham endwall design system and this paper provides details of the first experimental validation of this system. Overall the design system was found to perform successfully. Many other researchers have conducted endwall design, test and build exercises and the key advance here was to examine the effect of profiled endwalls on tip clearance flow. To this end a tip clearance was added to both the CFD and the cascade during the design process. The results show that even with an aspect ratio of two the endwall produces noticeable changes on the tip clearance flow. This does not however necessarily prevent a successful profiled endwall from being implemented in the cascade.

Investigation of a Tip Clearance Cascade in a Water Analogy Rig

1986 ◽  
Vol 108 (1) ◽  
pp. 38-46 ◽  
Author(s):  
J. A. H. Graham
Keyword(s):  
Turbine Blades ◽  
Flow Region ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Tip Clearance Flow ◽  
Pressure Profiles ◽  
Clearance Flow ◽  
Hot Film ◽  
Model Features

The tip clearance flow region of high-pressure axial turbine blades for small gas turbine engines has been investigated in a water flow cascade. The blade model features variable clearance and variable endwall speeds. The cascade is scaled for Reynolds number and sized to give velocities suitable for visualization. Pressure profiles were measured on one blade, and correlated with the visualization. Unloading is found to be a major feature of the pressure field at both tip and midspan, and is intimately connected with scraping effects and the behavior of the clearance vortex. Some initial hot-film velocity measurements are also presented.

Endwall Blockage in Axial Compressors

1999 ◽  
Vol 121 (3) ◽  
pp. 499-509 ◽  
Author(s):  
S. A. Khalid ◽  
A. S. Khalsa ◽  
I. A. Waitz ◽  
C. S. Tan ◽  
E. M. Greitzer ◽  
...  
Keyword(s):  
Tip Clearance ◽  
Design Parameters ◽  
Tip Clearance Flow ◽  
Axial Compressors ◽  
Clearance Flow ◽  
Flow Features ◽  
Physical Insight ◽  
Level Loading ◽  
Stagger Angle ◽  
Insight Into

This paper presents a new methodology for quantifying compressor endwall blockage and an approach, using this quantification, for defining the links between design parameters, flow conditions, and the growth of blockage due to tip clearance flow. Numerical simulations, measurements in a low-speed compressor, and measurements in a wind tunnel designed to simulate a compressor clearance flow are used to assess the approach. The analysis thus developed allows predictions of endwall blockage associated with variations in tip clearance, blade stagger angle, inlet boundary layer thickness, loading level, loading profile, solidity, and clearance jet total pressure. The estimates provided by this simplified method capture the trends in blockage with changes in design parameters to within 10 percent. More importantly, however, the method provides physical insight into, and thus guidance for control of, the flow features and phenomena responsible for compressor endwall blockage generation.

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