<p>&nbsp;The clearance between the blade tip and the casing in the high pressure compressor of a gas turbine is principally affected by the radial growth of the discs, which is caused by a combination of thermal and mechanical stresses. The knowledge of heat transfer coefficients is needed to predict the disc growth (and tip clearance), and these can be determined from the temperature distribution on the discs. Buoyancy-induced flow occurs in these heated, rotating compressor cavities. These cavities are generally open at the inner radius, where there is a transfer of heat and momentum with an axial throughflow of cooling air. In some designs, including industrial gas turbines, the cavity is closed, though buoyancy-induced flow still occurs. The closed cavity also describes the limiting case of an open cavity where the axial gap between the cobs reduces to zero.</p><p>This paper presents an experimental investigation into the effect of the rotational Reynolds number and buoyancy parameter (and therefore the Grashof number) on the behaviour of the heat transfer and rotating-flow structures in a closed, heated cavity. Steady-state shroud heat flux and disc surface temperature measurements were collected from the Bath Compressor-Cavity Rig over a wide range of engine-relevant conditions. Unsteady pressure measurements were also collected. Disc heat fluxes and Nusselt numbers were derived from the measured disc temperatures using a Bayesian model and the equations for a circular fin. A heat transfer correlation for the shroud was determined from the heat flux measurement and calculated cavity air temperatures adjacent to the shroud. The core slip velocity, as well as the number and size of the vortex pairs are derived from the unsteady pressure measurements.&nbsp;</p>

Measurement of Heat Transfer and Flow Structures in a Closed Rotating Cavity

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

Turbo Expo 2021

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.