High Speed Shadowgraph Visualization of the Unsteady Flow Phenomena in a Valveless Pulsejet Engine -video

Abstract

A pulsejet is a micro - propulsion device ideally suited for MAV applications because of its low cost, simplicity and scalability. Unsteady flow and complex mixing of fuel, air and residual hot gases in a pulsejet make analysis, modeling and scaling extremely challenging. A general methodology for the design of optimized pulsejet geometry is still not available. In order to evolve such a design methodology, high speed flow visualization, employing a unique twin-beam shadowgraph technique, has been effectively used to better understand the detailed pulsejet flow physics. An inline - intake, rectangular cross–section, valveless hydrogen-fuelled pulsejet, suitably modified with optical access for flow visualization was used for this experimental study. Visualisation of the unsteady combusting flow phenomena, under sustained pulsation, as well as at starting of the pulsejet has been studied using this high-speed shadowgraph technique. This technique has been shown to be a powerful tool to arrive at what need be promising inline-intake valveless pulsejet configurations. A pulsejet starting method, ideally suited for field applications such as in MAVs, using only an external flame torch igniter, has also been successfully developed