Summary of Recent Research on Detonation Wave Engines at UTA
A survey of recent research at UTA on detonation waves related to propulsion is presented in this paper. A brief historical review of the early pulse detonation engine (PDE) research at UTA is provided to lay the background for the development of a large-scale PDE Ground Demonstrator. Also current activities related to the development of rotating detonation wave engines (RDE) are reviewed. System integration studies for both PDE- and RDE-based propulsion systems are summarized, followed by a brief description of two programs focusing on application of detonation waves to hypersonic flow simulation and power generation.
Experimental study of propane-fueled pulsed detonation rocket
A major problem applying detonations into aero-propulsive devices is the transition of deflagration and weak detonation into CJ detonation. The longer this transition, the longer the physical length of the engine must be to facilitate the propagation of the flame. However, lengthening of the detonation chamber can significantly increase weight, rendering the reduction of deflagration-to-detonation (DDT) and weak detonation transition length of great importance. One of the most common means of shortening these lengths is with the aid of a Shchelkin spiral. A simple helical apparatus, it was used in early single-shot detonation investigations to over-exaggerate wall roughness effects. It was through empirical investigations that the reduced DDT phenomenon was observed. The present investigation explored the possibility of applying such an apparatus into an intermittent pulsed detonation device using gaseous C3H8/O2. Results show significant improvements in comparison to cases without the spiral. Tests through a range of cycle frequencies up to 20 Hz in oxygen-propane mixtures at 1 atm demonstrated the feasibility of the Shchelkin spiral in a pulsed mode. The results also demonstrated the need to optimize the chamber’s dimensions and various other associated processes to ensure that a detonation wave is sustained within the detonation chamber.
Flow features of shock-induced combustion around projectile traveling at hypervelocities
The shock-induced combustion with periodic unsteadiness around a projectile fired into hypersonic flows is numerically studied. The mechanism of periodic unsteadiness is clarified using an x-t diagram of the flow variable on the stagnation streamline. The frequencies of the periodic unsteadiness obtained quantitatively agree with the experimental observations. The key parameters which are responsible in triggering the instability and in determining the frequency of the periodic unsteadiness are discussed by using the time integration of the species equations. The result indicates that the key parameters are induction time, heat release, and concentration of the heat release. The induction time is a key parameter for the frequency of the unsteadiness. The concentration of heat release is important for the unsteadiness itself. Total energy creating the compression waves depends on the amount of heat release itself. All of these features are recognized in a simple zero-dimensional analysis.