Reduction of air flow rate for pulse-detonation-turbine-engine operation by water-droplet injection

Abstract

In this study, experiments on a pulse detonation turbine engine (PDTE) were conducted. The final goal of this work is the self-sustained operation of a PDTE system in which all of the air used for its operation is supplied by a turbine-compressor driven by pulsed detonations in the system itself. Currently, air used for PDTE operation is supplied by using an external device because the air flow rate for PDTE operation is too high. That is, air is used not only for combustion but also for purge of the residual hot burned gas in a pulse-detonation combustor (PDC), and sometimes for the control of the turbine-inlet temperature by blowing secondary air into a PDTE system downstream of the PDC. In this work, for reducing the air flow rate for PDTE operation, the water-droplet-injection technique was introduced in two ways. First, water droplets were injected into the PDC for purging the residual hot burned gas. Second, water droplets were injected into the PDTE system downstream of the PDC for controlling the turbine-inlet temperature. In particular, the effect of the latter was analyzed by using simple model calculations. As a result, the turbine-inlet temperature was precisely controlled by the water-droplet injection, and the air flow rate for PDTE operation was drastically reduced.