Tip clearance

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

Techniques for blade tip clearance measurements with capacitive probes

Abstract: This article presents a proven but advantageous concept for blade tip clearance evaluation in turbomachinery. The system is based on heavy duty probes and a high frequency (HF) and amplifying electronic unit followed by a signal processing unit. Measurements are taken under high temperature and other severe conditions such as ionization. Every single blade can be observed. The signals are digitally filtered and linearized in real time. The electronic set-up is highly integrated. Miniaturized versions of the electronic units exist. The small and robust units can be used in turbo engines in flight. With several probes at different angles in one radial plane further information is available. Shaft eccentricity or blade oscillations can be calculated.

Laser Doppler Anemometry Measurements in an Axial Compressor Stage

Abstract: The aim is to provide unsteady experimental data of the e owe eld in a benchmark one-stage axial compressor, to improvetheunderstanding ofthee owfeatures.Theinvestigationisconductedwitha two-componentlaserDoppler anemometer, and 32 axial locations are surveyed, from the rotor inlet to the stator outlet. Because laser Doppler anemometry is a nonintrusive device, data are obtained from the rotor row, providing information in a region dife cult to explore with other techniques. Limitation of blade shadowing is addressed with an adjustment of the laser head orientation, which permits reaching any point inside the rotor. Furthermore, a dual probe orientation gives two sets of measurements yielding three velocity components. The dynamics of the rotor tip clearance vortex is discussed in the interrow gap. There is a strong interaction between this vortex and the rotor bladewake. Phaseaveraged results show the unsteady e owe eld and the rotor ‐stator interaction. The rotor wakes are cut up by the stator row and are visible until the exit of the axial zone of measurements. Their interaction with the stator blades boundary layers creates strong time-dependent e ow structures resulting in phase lags between the rotor wakes at the stator outlet.

Three-Dimensional Flow and Mixing in an Axial Flow Compressor With Different Rotor Tip Clearances

Abstract: The effect of difference in rotor tip clearance on the mean flow fields and unsteadiness and mixing across a stator blade row were investigated using hot-wire anemometry, pressure probes, flow visualization and the ethylene tracer-gas technique on a single stage axial flow compressor. The structure of the three-dimensional flow fields was discussed based on results of experiments using the 12-orientation single slanted hot-wire technique and spectrum analysis of velocity fluctuation. High-pass filtered measurements of turbulence were also carried out in order to confirm small-scale velocity fluctuation which is more realistically referred to as turbulence. The spanwise distribution of ethylene gas spreading, estimated by the measured small-scale velocity fluctuation at the rotor exit, agreed quite well with that which was experimentally measured. This fact suggests the significant role of turbulence, generated within the rotor, in the mixing process across the downstream stator. The value of the maximum mixing coefficient in the tip region was found to increase linearly as the tip clearance became enlarged, starting from the value at midspan.Copyright © 1991 by ASME