High Resolution Experimental and Computational Methods for Modelling Multiple Row Effusion Cooling Performance

Abstract

The continuing rise in turbine entry temperatures has necessitated the development of evermore advanced cooling techniques. Effusion cooling, which is characterised by a high density of film holes operating at low blowing ratios, represents one possible mechanism for achieving high overall cooling effectiveness. This paper presents an experimental investigation performed on flat-plate, effusion-type cooling geometries (with primary hole pitches of 3.0D and 5.75D) using pressure sensitive paint to yield high-resolution film effectiveness distributions using the heat/mass transfer analogy. CFD was used to model the setup computationally, with results comparing favourably to the experiments. The CFD domain was then altered to model a single hole. A superposition method was developed and applied to the two dimensional film effectiveness distribution, yielding data for an array of closely-packed holes. The method produced satisfactory results at higher pitches, but at lower pitches, high levels of jet interactions reduced the performance of the superposition method.

Laminar transpiration cooling experiments in hypersonic flow

“…Case 4 and Case 6, the coolant likely diffuses laterally and therefore the film is wider than the span of the injector (injector edge is at z = 40 mm). This effect could also be due to the detachment of the boundary-layer over the injector at these high blowing ratios (Murray et al 2017) and the resulting kidney vortices at the span-wise edges of the injector (Haven and Kurosaka 1997).…”

Multiscale analysis of thermomechanical stresses in double wall transpiration cooling systems for gas turbine blades

“…To determine the steady state temperature field shown in Fig 2c we employ the decoupled conjugate technique developed by Murray et al [10], which consists of three major steps: 1) a computational Fluid Dynamics (CFD) simulation using the repeating block model in Fig 2a, 2) the processing of CFD results through empirical correlations proposed by Goldstein [46] and Sellers [47],…”

“…Key challenges for incorporating DWTC into real engines is: the maintenance of adequate coolant flow with minimum turbine stage efficiency losses [10]; the production of the required film distribution with minimum mixing with the mainstream flow [11]; the manufacturing of intricate architectures [11,12]; and the design against creep-fatigue failure [13].…”

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

“…This is because improved thermal protection allows for higher gas temperatures to operate in the core of turbines, which increases engine efficiency and specific power output [10]. Indeed, this idea is well established in engine design [2,11] and over the last fifty years has contributed to the rise of the operating engine core temperature more than other relevant technological advances related to nickel superalloys, thermal barrier coatings and manufacturing [12,13]. Consequently, exploring increasingly sophisticated thermal protection systems is key for addressing emerging environmental and energy challenges [11,13].…”