Measurement of a swirling pipe and combustion chamber flow by means of multi-component Laser Doppler Velocimetry

Abstract

Swirl flows with a non-zero circumferential velocity are of great interest because of their multiple applicability in an industry. They occur in a wide range of applications, such as gas turbines, gasoline and diesel engines, and industrial furnaces. The general effect of introducing swirl on jet flows is to cause an increase in width and rate of entrainment. It is noted that if the strength of swirl is greater than a certain critical value, the forces due to the induced pressure gradients exceed the forward kinetic forces, leading to the flow reversing its direction on the axis of symmetry and thus generating central toroidal recirculation zone. This chapter presents a simplified swirl generator essentially chosen to perform measurements by means of 3D-Laser Doppler Velocimetry (LDV). It allows determining the share of the periodic velocity fluctuations because of the precessing vortex core of the total fluctuations.