Analysis of Upstream Turbulence Impact on Wall Heat Transfer in an Acoustic Liner with Large-Eddy Simulations

Abstract

Acoustic liners of aircraft fan ducts generate synthetic jets that interact with the boundary layer of the incident grazing flow. Such an interaction leads to complex wall heat transfer, which has been scarcely studied. The objective of the present work is to evaluate the flow dynamics and the heat transfer mechanisms that occur in acoustic liners by the use of Large-Eddy Simulations. To do so, two configurations, linked by a principle of similarity, are considered: a lab-scale one, for which dimensions have been multiplied by a factor of 6.25 to ease measurements, and an engine-scale configuration. The lab-scale configuration is used to validate the numerical methodology and, although some limitations are pointed out, the similitude is validated. As a main outcome of these detailed simulations, synthetic jets are found to completely drive the flow dynamics in the jet wakes. Upstream turbulence is also shown to impact the development of the first jet rows as well as the wall heat transfer between jets.