Session: 36-02 Hot Section Deposition

Paper Number: 81157

81157 - Numerical Investigation of Particle Deposition in Double Wall Effusion Cooled Systems 

In the pursuit of ever-higher thermal efficiency, aero-engines have seen their turbine entry temperatures rise steadily driving the need for highly effective cooling systems. Double-walled, effusion-cooled turbine blades, which combine arrays of impingement holes and pedestals, with full-coverage external film cooling offer the potential for significantly better cooling than conventional multi-pass blade cooling systems.  However, this technology includes intricate geometric features with high curvature which are susceptible to blockage from dust and sand. Such deposition has the potential to compromise the flow and cooling performance.

In this paper the vulnerability of each element of engine models of two generic double-walled cooling schemes, incorporating diamond pedestals, is predicted using Arizona Road Dust as test contaminant and both CMSX4 and SS304 as blade material.  The prediction uses a bespoke continuous random walk model to predict the arrival of particles at the blade surface, while a new bounce-stick model generated from a Direct Element Methods approach is employed to predict the particle behaviour after impact. 

An experimental campaign was conducted on a test article for comparison to the model predictions. Here, coolant air and metal temperatures were set to be representative of a typical large civil jet engine. Flow conditions in the fluid and discrete phase were appropriately dimensionally matched to engine operating conditions. Bulk and spatially resolved depositions are reported for each of the cooling system components. The results are used to investigate the susceptibility of the system to particle blockage and to develop a reduced-order model able to predict deposition fractions based on a newly formulated generalised Stokes number.

Presenting Author: Florian Villain University of Oxford

Presenting Author Biography: Florian is undertaking his DPhil through the Centre for Doctoral Training in Future Propulsion and Power. <br/>He completed his Master of Research degree at the University of Cambridge as<br/>part of the same program, following undergraduate studies at Imperial College London. His<br/>research focuses on particulate deposition in secondary air systems of gas turbines, in the context of high-performance quasi-transpiration cooling.<br/>Predicting deposition and hence performance deterioration is desirable both to quantify the cost of ownership effects that arise from atmospheric contaminants and to allow the optimisation of component design to<br/>guarantee air travel safety. His current work investigates how particles interact with cooling passages as well as how to predict and/or mitigate those interactions.

Authors:

Florian Villain University of Oxford
Nikul Vadgama University of Oxford
Jack Gaskell University of Oxford
Peter Ireland University of Oxford
Matthew Mcgilvray University of Oxford
David Gillespie University of Oxford