Tip clearance

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

Compressor of turbine blade manufacture

Abstract: A turbine or compressor blade holding fixture and machining method contemplates the subassembly of all the blades 20 upon the rotor 12 of the compressor or turbine. Fixture rings 30, 32 along with radial biasing members in the form of annular o-rings 40, 42, 44 are intersecured to opposite sides of the blades 20 so as to radially position the latter in their normal "running position" while so mounted on the rotor 12 of the wheel. In such condition all of the blades 20 may be simultaneously machined such that the outer tips 24 thereof lie on a true uniform, desired outer diameter to provide subsequently uniform tip clearance to the surrounding shroud when mounted in a gas turbine engine for operation.

Tip Clearance Effect on the Flow Pattern of a Radial Impulse Turbine for Wave Energy Conversion

Abstract: Turbines for wave energy conversion have a special feature to be taken into account in the study of the tip leakage flow: These turbines are self-rectifying, which work inside a cyclically bidirectional flow alternatively as an inflow/outflow turbine The phenomena at the blade tip will be different in these two situations Moreover, it is necessary to take into account the tip clearance of the guide vanes because it has a significant influence on the rotor performance A previously developed numerical model has been used for this study The geometry proposed by Setoguchi (2002, “A Performance Study of a Radial Impulse Turbine for Wave Energy Conversion ,” Journal of Power and Energy, 216, pp 15–22) is used in the model Three different tip clearance sizes have been simulated to compare the influence of the tip clearance size on the performance Results show that changing the size of the tip clearance from 0% to 4% of the blade span reduces the turbine maximum efficiency by up to 8% However, the efficiency reduction is more pronounced when the turbine works as an inflow turbine because the tip clearance effect is more important in the inner part of the rotor, since flow velocities are higher and the relative casing motion is lower This study achieves its main aim, which is to improve knowledge about the phenomena related to the tip clearance and its influence on the performance of radial impulse turbines

Effect of blade tip geometry on tip leakage vortex dynamics and cavitation pattern in axial-flow pump

Abstract: A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.

The Measurement and Prediction of the Tip Clearance Flow in Linear Turbine Cascades

Abstract: This paper describes a simple two-dimensional model for the calculation of the leakage flow over the blade tips of axial turbines. The results obtained from calculations are compared with data obtained from experimental studies of two linear turbine cascades. One of these cascades has been investigated by the authors and previously unpublished experimental data is provided for comparison with the model. In each of the test cases examined, excellent agreement is obtained between the experimental and predicted data. Although ignored in the past, the importance of pressure gradients along the blade chord is highlighted as a major factor influencing the tip leakage flow.Copyright © 1992 by ASME