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Tip clearance

About: Tip clearance is a research topic. Over the lifetime, 2637 publications have been published within this topic receiving 32671 citations.


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01 Nov 1972
TL;DR: A program of analysis, design, fabrication, and testing has been conducted to predict the effects of impeller blade clearance on centrifugal pumps and the relationship between the head coefficient and torque loss with tip clearance was established.
Abstract: A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and the relationship between the head coefficient and torque loss with tip clearance was established. Analysis were performed to determine the cost variation in design, manufacture, and test that would occur between unshrouded and shrouded impellers. An impeller, representative of typical rocket engine impellers, was modified by removing its front shroud to permit variation of its blade clearances. It was tested in water with special instrumentation to provide measurements of blade surface pressures during operation. Pump performance data were obtained from tests at various impeller tip clearances. Blade pressure data were obtained at the nominal tip clearance. Comparisons of predicted and measured data are given.

13 citations

01 Jan 1987
TL;DR: In this article, the effect of tip clearance losses on the performance of the stage performances of the pumps due to tip clearance loss was studied on the basis of experiments on five pumps of different specific speed.
Abstract: Why do some centrifugal impellers exhibit high sensitivity to tip clearance losses while others don’t? This may be understood by considering the geometric and fluid mechanics design parameters of the impellers. On the basis of experiments on five pumps of different specific speed, the relative effect on the stage performances of the pumps due to tip clearance is studied and earlier works in the field are discussed.

13 citations

Proceedings ArticleDOI
03 Jun 2013
TL;DR: In this paper, particle image velocimetry (PIV) measurements at high spatial resolution in the blade tip region of the Darmstadt Transonic Compressor Rotor-1 under the influence of a bend-slot CT were performed.
Abstract: The application of casing treatments (CT) is an effective measure to increase the stable operating range of modern aero engine or gas turbine compressors. As the development and design process of optimized CT geometries is primarily based on numerical simulations, the need for accurate experimental flow field data for related code validation is increasing with the number of applications. While the stall margin enhancement and other stage characteristics can be verified using conventional measurement techniques such as pressure and temperature probes, a deeper insight to the aerodynamic effect of the CT on the rotor flow field can only be provided using non-intrusive, laser-based flow field diagnostics, given that optical access to the compressor stage can be established.The investigation presented herein involved particle image velocimetry (PIV) measurements at high spatial resolution in the blade tip region of the Darmstadt Transonic Compressor Rotor-1 under the influence of a bend-slot CT. Tangential PIV measurement planes were placed at 95% span as well as in the tip gap of the rotor. The investigation included operating conditions at the aerodynamic design point (peak efficiency) and near stall conditions at 100% rpm. Additional reference measurements were performed with the untreated, smooth casing. The experimental study was complimented by numerical simulations of the same compressor and CT geometry using the DLR TRACE code. Based on the combination of both, experimental and numerical flow field results, a detailed analysis of the shock structures and the tip clearance vortex under the influence of the CT was performed.Under the influence of the CT, the fluid exchange between rotor passage and CT slots — driven by the pressure gradient over the blade tip and the leading edge bow shock, respectively — induces secondary flow structures in the tip vortex regime. At near stall conditions the periodical injection of energized fluid out of the CT cavities was identified to be one of the major effects stabilizing the tip clearance vortex and hence delaying the onset of rotating stall.Copyright © 2013 by ASME

13 citations

Proceedings ArticleDOI
01 Jan 2008
TL;DR: In this article, the authors describe experimental investigations of the tip clearance vortex in a linear compressor cascade with a tip clearance to one side and a compressor with a rotor tip section represented by the cascade.
Abstract: The paper describes experimental investigations of the tip clearance vortex in a linear compressor cascade with a tip clearance to one side and a compressor with a rotor tip section represented by the cascade. The aim is to show experimentally that breakdown of the tip clearance vortex can take place in subsonic compressors. As a first step, the flow in the linear compressor cascade has been investigated at different flow angles from the design point up to the stability limit of the cascade. In a second step the flow in the tip region of the rotor in a low-speed single-stage compressor has been investigated from the design point up to the stall limit of the compressor. The analysis of PIV measurements reveal a low momentum fluid area in the passage both in the cascade and the compressor when approaching the stall limit. This area is separated from the main flow by an interface that is characterized by high standard deviations of the velocities. The location of this interface correlates well with the positions at which the analysis of the unsteady pressure signals obtained with several flush mounted high-response pressure transducers reveals a bump of increased amplitude at a certain nondimensional frequency. The results in the compressor are for the most part identical to those obtained in the cascade. When approaching stall a distinct bump shows up in the casing wall pressure spectra at a nondimensional frequency comparable to the nondimensional frequency found in the cascade. At the same time an area of very low momentum fluid accumulates in the vicinity of the original vortex axis, as can be shown by PIV measurements in the rotor of the compressor. Additionally it can be shown, that the blockage that is due to the broken down tip clearance vortex leads to a rotating phenomenon, comparable to the phenomenon of ‘rotating instabilities’.© 2008 ASME

13 citations

Journal ArticleDOI
TL;DR: In this article, the C106 four-stage compressor was investigated in a two-dimensional rectangular duct flow to reveal the mixing mechanism in the corner region similar to those formed by blade surfaces and endwalls in a compressor.
Abstract: This paper follows directly from Part I which contains not only the description of the facilities and the results for the C106 four-stage compressor but also the background, list of nomenclature, acknowledgement and references. The discussion and conclusions for Part I and Part II are given here. The single stage compressor results show the significant effects of inlet guide vane (IGV) wakes on mixing across the stage in the so called ‘free stream’ region; in the casing region tip clearance flow is shown to play an important role in mixing. Explanations for these results are given. Investigations were also carried out in a two-dimensional rectangular duct flow to reveal the mixing mechanism in the corner region similar to those formed by blade surfaces and endwalls in a compressor. Turbulent diffusion has been found to be the dominant mechanism in spanwise mixing; anisotropic inhomogeneous turbulent diffusion is mainly responsible for the non-uniform mixing in the corner region. The larger spread of tracer gas in the tangential direction than in the radial direction is mainly caused by the wake dispersion and relative flow motions within the blade wakes as well as secondary flow contributions in the end-wall regions.Copyright © 1990 by ASME

13 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202354
2022149
202189
2020111
2019116
201897