Topic
Tip clearance
About: Tip clearance is a research topic. Over the lifetime, 2637 publications have been published within this topic receiving 32671 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: The results indicate that the PVDF sensor array is capable of the dynamic pressure field measurement over the blade tip, and superior to the conventional approaches in installation, spatial resolution, frequency response, and cost.
Abstract: Tip clearance flow in axial flow compressor is unavoidable and responsible for pressure losses and noise generation and influences the stability of the compressor. However, necessary flow measurement in the blade tip region is a great challenge due to the small gap width as well as the structure limitation. In this paper, a polyvinylidene fluoride (PVDF) piezoelectric-film sensor array is developed to capture the dynamic pressure field over the blade tip in an axial flow compressor. The PVDF sensor array with 40 evenly distributed sensing points is fabricated directly on a 30 μm thick aluminum-metalized polarized PVDF film through photolithography. Dynamic calibration of the sensor is accomplished using acoustic source as excitation and a microphone as a reference. The test pressure range is up to 3.5 kPa and the sampling frequency is 20 kHz. The sensor presents a high signal-to-noise ratio and good consistency with the reference microphone. Sensitivity, frequency response, linearity, hysteresis, repeatability as well as the influence of temperature are also investigated through the calibration apparatus. The calibration gives credence to the relevance and reliability of this sensor for the application in dynamic pressure field measurement. The sensor is then applied to an actual measurement in a compressor. The output of the PVDF sensor array is also compared with the results of common pressure transducers, and the features of the dynamic pressure filed are discussed. The results indicate that the PVDF sensor array is capable of the dynamic pressure field measurement over the blade tip, and superior to the conventional approaches in installation, spatial resolution, frequency response, and cost. These advantages indicate its potential broad application in pressure measurement, especially for the complex spatial surface or thin-walled structure, such as the blade surface and the thin casing wall of the compressor.
15 citations
03 Jun 1991
TL;DR: In this article, the formation of the tip clearance vortex and the passage vortices is presented, which are strongly influenced by the spanwise non-uniform stator outlet flow.
Abstract: Detailed measurements have been performed in a subsonic, axial-flow turbine stage to investigate the structure of the secondary flow field and the loss generation. The data in- cludes the static pressure distribution on the rotor blade passage surfaces and radial-cir- cumferential measurements of the rotor exit flow field using three-dimensional hot-wire and pneumatic probes. The flow field at the rotor outlet is derived from unsteady hot-wire measurements with high temporal and spatial resolution. The formation of the tip clearance vortex and the passage vortices is presented, which are strongly influenced by the spanwise non- uniform stator outlet flow. Taking the experi- mental values for the unsteady flow velocities and turbulence properties, the effect of the periodic stator wakes on the rotor flow is discussed. Nomenclature b, � axial chord Cvelocity, absolute frame hspan nshaft speed pstatic pressure p, total pressure schord tpitch ucircumferential speed u' random axial velocity fluctuation v' random radial velocity fluctuation wvelocity, relative frame w' random circumferential velocity fluctuation Zblade number aflow angle in circumferential direction, absolute frame 6� flow angle in circumferential direction, relative frame d, tip clearance tv, reduced frequency Subscripts
15 citations
TL;DR: In this paper, a two-bladed model turbine was shrouded by a constant-diameter pipe and the tip clearance was sufficiently small to minimise and localise the turbine tip clearance losses.
15 citations
Patent•
15 Dec 2006TL;DR: In this paper, a system and method for actively managing blade tip clearances in a turbine engine, particularly under start up and steady state operating conditions, is described, where the rotor can be cooled while the blade ring can be heated.
Abstract: Aspects of the invention relate to a system and method for actively managing blade tip clearances in a turbine engine, particularly under start up and steady state operating conditions. During start up, the rotor can be cooled while the blade ring can be heated. During steady state operation, the rotor may be heated while the blade ring may be cooled. The sources of the heating fluid and cooling fluid can be compressor delivery air, boiler steam and ambient air. The fluids can be compressed to maintain efficiency.
15 citations
TL;DR: Rotor tip clearance height and the associated tip leakage flow have a significant effect on the performance and stability of compressors as mentioned in this paper, and existing studies considering tip clearance effects on stabler stability are limited.
Abstract: Rotor tip clearance height and the associated tip leakage flow have a significant effect on the performance and stability of compressors. Existing studies considering tip clearance effects on stabi...
15 citations