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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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Patent
22 Apr 1997
TL;DR: In this article, a rotor tip clearance control apparatus (SCC) comprises a plurality of circumferentially arranged spaced wall members, each of which has at least one fluid passage, and each wall member is mounted on a carrier attached to an annular casing.
Abstract: A blade tip clearance control apparatus (10) comprises a plurality of circumferentially arranged spaced wall members (16) located adjacent the rotor path of a plurality of rotor blades (14). Each wall member (16) is mounted on a carrier (18) attached to an annular casing (22) radially outward thereof. Thermal expansion or contraction of the carrier (18) causes radial movement of the wall members (16). The wall members (16) have at least one fluid passage (20) therein. In operation a flow of fluid passing through the fluid passages (20) causes either thermal expansion or contraction of the wall member (16) to different radial positions.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the heat transfer and film cooling effects of cavity tip and winglet-cavity tip have been numerically investigated with blade tip and casing coolant injection with a turbine cascade exit Ma number 0.96.

11 citations

Proceedings ArticleDOI
01 Jan 2009
TL;DR: In this article, the collective effect of tip line sweeping and tip clearance on axial flow turbomachines was investigated. But the authors focused on the collective effects of sweep and clearance.
Abstract: There are a number of performance indices for a turbomachine on the basis of which its strength is evaluated. In the case of axial compressors, pressure ratio, efficiency and stall margin are few such indices which are of major concern in the design phase as well as in the evaluation of performance of the machine. In the process of improving the blade design, 3D blade stacking, where the aerofoil sections constituting the blade are moved in relation to the flow. Tilting the blade sections to the flow direction (blade sweep) would increase the operating range of an axial compressor due to modifications in the pressure and velocity fields on the suction surface. On the other hand, blade tip gap, though finite, has great influence on the performance of a turbomachine. The present work investigates the combined effect of these two factors on various flow characteristics in a low speed axial flow compressor. The objective of the present paper is thereby confined to study the collective effects of sweep and tip clearance without attempting to suggest an outright new design. In the present numerical work, the performance of Tip Chordline Sweeping (TCS) and Axial Sweeping (AXS) of low speed axial compressor rotor blades are studied. For this, 15 computational domains were modeled for five rotor sweep configurations and three different clearance levels for each rotor. Through the results, 20°AXS rotor is found to be distinctive among all the rotors with highest pressure rise, higher operating range and less tip clearance loss characteristics. TCS rotors produced improved total pressure rise at the low flow coefficients when the tip gap is increased. Hence there is a chance that an “optimum” tip gap exists for the TCS rotors in terms of total pressure coefficient and operating range, while AXS rotors are at their best with the minimum possible clearance.Copyright © 2009 by ASME

11 citations

Proceedings ArticleDOI
22 Dec 2010
TL;DR: In this paper, the authors used delayed-detached Eddy simulation (DDES) to simulate rotating stall inception of NASA Rotor 67, a low-aspect-ratio transonic axial flow fan with a tip speed of 429 m/s and a pressure ratio of 1.63.
Abstract: This paper uses the advanced Delayed-Detached Eddy Simulation (DDES) of turbulence to simulate rotating stall inception of NASA Rotor 67. The rotor is a low-aspect-ratio transonic axial-flow fan with a tip speed of 429 m/s and a pressure ratio of 1.63. A full annulus simulation was employed with the time accurate compressible Navier-Stokes code in order to accurately capture the the formation of long-length disturbance and a short-length inception (spike). The validation for all numerical methods used in this study was accomplished by the comparisons of the CFD solutions with the test data in advance of unsteady simulations. Self-induced rotating stall development is simulated holding the same back pressure at the near stall experiment without any throttling. Spike type rotating stall occurs and rotates at roughly 50% of rotor speed counter to the rotation. After spike onset, rotating stall fully develops approximately within 2 rotor revolutions. Two distinct characteristics that can advance the mechanism of spike type rotating stall are observed. First, the passage shock is fully detached from rotor and decays during the spike inception. Consequently the shifted sonic line at the upstream of rotor allows stalling flow to propagate to the neighboring passage. Second, the trailing edge back flow contributes to the build up of a fully developed stall cell by pushing tip clearance flow toward blade leading edge and inducing tip spillage flow. Tip vortex originated from the leading edge dies out during spike inception as the swirl angle of incoming tip flow decreases, while in the unstalled passages it develops without breakdown. DDES challenge for the complete blade row reflects well the sequence of rotating stall and its unsteady behavior.Copyright © 2010 by ASME

11 citations

Journal ArticleDOI
05 Aug 2020-Energies
TL;DR: In this article, the effect of tip-leakage vortex (TLV) induced in the end-wall region was numerically illustrated by using the shear-stress transport (SST) k-ω turbulence model at various flow conditions and different tip-clearance sizes.
Abstract: Unavoidable tip clearance between blade tip and casing shroud plays an important role in the performance and characteristics of a tidal propeller turbine. In this work, the tip-leakage vortex (TLV) induced in the end-wall region was numerically illustrated by using the shear-stress transport (SST) k–ω turbulence model at various flow conditions and different tip-clearance sizes (TCSs). The swirling strength criterion was employed to visualize the tip-leakage vortex trajectory and investigate vortex evolution according to clearance size change. Although TLV occurs in both design and off-design conditions, vortex intensity develops strongly under excess flow rate with increased tip gap. The extreme influence of TCS on the turbine’s generated power and efficiency was predicted in steady simulations for four TCS cases, namely, δ = 0%, 0.25%, 0.5%, and 0.75%. With the extension of the tip gap, turbine performance was drastically reduced because of vigorous turbulent leakage flow combined with considerable volumetric loss. The effect of TCS on pressure fluctuation intensity were also explored on the basis of the transient simulation statistic. Maximal pressure variation amplitude and dominant frequency were presented in spectrum analysis utilizing fast Fourier transform.

11 citations


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