Engine System Performance of Pulse Detonation Concepts Using the NPSS Program

Abstract

The Numerical Propulsion Systems S imulation (NPSS) tool has been used to analyze several Pulse Detonation Engine (PDE) concepts that have been of interest lately. The PDE cycle approximates a constant volume combustion process which results in both a temperature and pressure rise across t he device. In this study, the PDE was modeled using standard shock tube relationships and flow into and out of the device was assumed to be steady state. The capabilities of NPSS in modeling this concept will be discussed. An analysis was completed comp aring a PDE to a conventional ramjet. For the purposes of the study, the PDE was modeled as a ramjet with a detonation chamber instead of the conventional combustor (basic PDE). Comparisons were made on thrust, specific fuel consumption (SFC), and engine pressure ratio over a range of peak temperatures. The unsteady flow characteristic of the PDE has the potential to degrade inlet and nozzle performance relative to steady flow. A short parametric study was completed to gauge the overall performance impa ct of changes to inlet and nozzle performance. The incorporation of a detonation tube into the core of a high bypass turbofan engine (~100,000 lb. thrust class) was also investigated. Thrust and SFC comparisons are made along with comments on changes req uired to the system in order to incorporate such a device into a high bypass turbofan engine. Finally, a brief discussion is included on the usefulness of this level of analysis of PDE concepts. Areas of concern will be noted with possible workarounds id entified. NPSS Analysis Tool