Pulse Detonation Engine Performance Research Articles

The flowfield and performance of pulse detonation engines

Numerical simulations of an idealized pulse detonation engine consisting of a tube closed at one end and open at the other are presented in this paper. Uncertainties noted previously in the specification of open-boundary conditions in one-dimensional simulations are resolved by conducting multidimensional simulations and extracting the needed information. Further confidence in the simulations is gained by comparing some of the computed flow variables with recent experimental data. The results from the simulations are then used to elucidate the detailed features of the flowfield and the role of key parameters that determine the overall propulsive performance. Specific values for the performance measures of a pulse detonation engine operating on a stoichiometric ethylene/oxygen mixture are calculated from the simulations to be 2100 N s/m 3 for the impulse (independent of system size), 163–165 s for the mixture-based specific impulse and 725–740 s for the fuel-based specific impulse. The computed performance measures are found to be in good agreement with most experimental data and an explanation is provided where differences are observed. Results from various simulations are used to arrive at a general expression that can be used to estimate the impulse from various detonable mixtures.

A Simplified Analysis on a Pulse Detonation Engine Model.

The performance of pulse detonation engines was analytically estimated by using a simple model. A pulse detonation engine was modeled as a straight tube. One end of the tube was closed and the other was open, and a detonation wave was ignited at the closed end. One cycle of the pulse-detonation-engine operation was divided into three phases: combustion, exhaust, and filling phases. The combustion and exhaust phases were theoretically analyzed with some simplifications, using the Hugoniot relation for the Chapman-Jouguet detonation wave and flow relations for self-similar rarefaction waves. Based on the simplified theoretical analysis, useful formulas for impulse density per one-cycle operation and time-averaged thrust density were derived.

Thermodynamic Cycle Analysis of Pulse Detonation Engines

Pulse detonation engines (PDEs) are currently attracting considerable research and development attention because they promise performance improvements over existing airbreathing propulsion devices. Because of their inherently unsteady behavior, it has been difficult to conveniently classify and evaluate them relative to their steady-state counterparts. Consequently, most PDE studies employ unsteady gasdynamic calculations to determine the instantaneous pressures and forces acting on the surfaces of the device and integrate them over a cycle to determine thrust performance. A classical, closed thermodynamic cycle analysis of the PDE that is independent of time is presented. The most important result is the thermal efficiency of the PDE cycle, or the fraction of the heating value of the fuel that is converted to work that can be used to produce thrust. The cycle thermal efficiency is then used to find all of the traditional propulsion performance measures. The benefits of this approach are 1) that the fundamental processes incorporated in PDEs are clarified; 2) that direct, quantitative comparisons with other cycles (e.g., Brayton or Humphrey) are easily made; 3) that the influence of the entire ranges of the main parameters that influence PDE performance are easily explored; 4) that the ideal or upper limit of PDE performance capability is quantitatively established; and 5) that this analysis provides a basic building block for more complex PDE cycles. A comparison of cycle performance is made for ideal and real PDE, Brayton, and Humphrey cycles, utilizing realistic component loss models. The results show that the real PDE cycle has better performance than the real Brayton cycle only for flight Mach numbers less than about 3, or cycle static temperature ratios less than about 3. For flight Mach numbers greater than 3, the real Brayton cycle has better performance, and the real Humphrey cycle is an overoptimistic (and unnecessary) surrogate for the real PDE cycle.

詳細化学反応を含む２次元数値流体力学によるＰＤＥ性能予測

One-dimensional numerical analyses of pulse detonation engine (PDE) have been performed by numerous workers. In one-dimensional codes, however, it is basically difficult to set adequate boundary conditions at exit plane, although PDE performance depends strongly on the boundary conditions. To evaluate the influence of boundary conditions, we performed a two-dimensional analysis for a straight single PDE, flying in an external environment under different fuel/oxidizer equivalence ratios. As a result, the physical processes in one PDE cycle and associated PDE performance are acquired.