Topic
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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TL;DR: In this paper, an extensive numerical investigation of a high pressure turbine stage operating at engine-representative non-dimensional parameters (Reynolds and Mach number, temperature ratios) was performed using the Numeca FINE/Turbo suite, adopting the k-ω SST turbulence model to investigate the aerodynamic and heat transfer characteristics in the tip region.
26 citations
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26 citations
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TL;DR: In this article, it is shown that as a swirling leakage flow passes through a pressure rise, such as in the aft portion of the suction side of a turbine blade, the mixed-out loss can either decrease or increase.
Abstract: Numerical simulations have been carried out to define the loss generation mechanisms associated with tip leakage in un-shrouded axial turbines. Tip clearance vortex dynamics are a dominant feature of two mechanisms important in determining this loss: (i) decreased swirl velocity due to vortex line contraction in regions of decreasing axial velocity, i.e., adverse pressure gradient and (ii) vortex breakdown and reverse flow in the vortex core. The mixing losses behave differently from the conventional view of flow exiting a turbine tip clearance. More specifically, it is shown, through both control volume arguments and computations, that as a swirling leakage flow passes through a pressure rise, such as in the aft portion of the suction side of a turbine blade, the mixed-out loss can either decrease or increase. For turbines the latter typically occurs if the deceleration is large enough to initiate vortex breakdown, and it is demonstrated that this is the case in modern turbines. The effect of blade pressure distribution on clearance losses is illustrated through computational examination of two turbine blades, one with forward loading at the tip and one with aft loading. A 15% difference in leakage loss is found between the two, due to lower clearance vortex deceleration (lower core static pressure rise) with forward loading, and hence lower vortex breakdown loss. Additional computational experiments, carried out to define the effects of blade loading, incidence, and solidity, are found to be consistent with the proposed ideas linking blade pressure distribution, vortex breakdown and turbine tip leakage loss.© 2012 ASME
26 citations
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31 Oct 2008TL;DR: In this article, a method for inspecting blade tip clearance between at least one rotor blade and a case spaced radially outward from the rotor blade is provided, which includes inserting a probe into an aperture defined in the case and emitting electromagnetic energy into the case using the probe.
Abstract: A method for inspecting blade tip clearance between at least one rotor blade and a case spaced radially outward from the rotor blade is provided. The method includes inserting a probe into an aperture defined in the case and emitting electromagnetic energy into the case using the probe. The method also includes detecting electromagnetic energy reflected from a blade tip portion of the rotor blade and determining a blade tip clearance defined between the blade tip and the case based on the detected electromagnetic energy.
26 citations
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TL;DR: In this paper, the effect of five blade tip patterns on performance and acoustics of a twin-stage variable-pitch axial fan is investigated numerically and the best tip pattern is determined by comparing the overall performance under the condition of those patterns carving in stage I impeller, and the performance promotion is then examined under the selected tip grooving in stage II impeller and both two stage impellers.
26 citations