Analytic and numerical Green's functions in an aeroengine Seminar

Abstract

In this talk we will consider Green's functions in an aeroengine, with applications to Fan noise. Fan noise comes from the aerodynamic interaction between the fan blades and stators as air flows between them, and is influenced by many factors such as position and number of blades. We use a model of an infinite duct as the engine casing and consider the fan blades as some rotating surface and air flowing through the duct. To understand the noise, we use the Euler equations to derive a sixth order partial differential equation for pressure in the duct. To solve the differential equation we first look for a Green's function, which can be done numerically or analytically. Our main focus in this talk is comparing the analytic and numerical Green's function. We begin by assuming the base flow has shear and swirl components in a constantly lined duct, and show the assumption of no swirl gives completely different results. We then later consider what happens as we add variable entropy and, if time allows, a lining which varies with position.