Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped With a Mean-Camberline Strip

Abstract

Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines(>100MW). In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or “squealer” as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer.

Modelling of heat transfer and fluid flow in the hot section of gas turbines used in power generation: A comprehensive survey

“…However, prior to the transition, there is no appreciable effect shown in the exit Mach numbers . The boundary layer remains attached as before the transition …”

“…Usually, there is a clearance between the blade tip and the stationary casting or shroud, as shown in Figure . This clearance is an essential geometrical feature to enable possible thermal and mechanical expansions . It also allows rotational movement of the blades without contacting the stationary casing .…”

“…Empirical modelling on heat transfer and flow field characteristics relevant to the turbine blade tip region can be found in literature. Bunker et al reported results of an experimental study investigating the convective heat transfer coefficient on the flat tip blade surface of the sharp and round edges of large power generation turbines. This experimental model was later simulated by Ameri and Bunker .…”

“…Bunker et al reported results of an experimental study investigating the convective heat transfer coefficient on the flat tip blade surface of the sharp and round edges of large power generation turbines. This experimental model was later simulated by Ameri and Bunker . Their simulation results showed good agreement with results reported by Bunker et al Figure shows the experimental and computational profiles of tip heat transfer coefficients for sharp and rounded edge tips …”

“…Ameri and Bunker investigated the convective heat transfer coefficient across the first‐stage blade tip surface of large‐scale power generation turbines. Simulations were performed using a multiblock computer code.…”