Jian-Ping Wang

Numerical Investigation of Rotating Detonation Engine Propulsive Performance

A series of 3- and 2-dimensional numerical simulations of a rotating detonation engine (RDE) are carried out with a 1-step chemical reaction model to investigate the RDEs propulsive performance. First, the performance is computed by a 3-dimensional simulation. After the initial instability dies down, the specific impulse and mass flux of RDE converge to constant values. Then, some simplified 2-dimensional cases are simulated. The following propulsive performance collusions are obtained: with the injection stagnation pressure increases, the mass flux increases linearly and the specific impulse decreases a little. With combustor length larger than a special value, specific impulse and mass flux change a little. The propulsive parameters obtained from the 3-dimensional simulation case agree with simplified 2-dimensional simulation cases.

Analytical and Numerical Investigations of Wedge-Induced Oblique Detonation Waves at Low Inflow Mach Number

The wedge-induced oblique detonation wave (ODW) at low inflow Mach number is investigated via Rankine–Hugoniot analysis and numerical simulations. The results show that the Chapman–Jouguet oblique detonation wave (CJ ODW) plays a significant role in the structure of the ODW. And the influence of the CJ ODW is the reason why an attached ODW can propagate upstream. Both the analytical and numerical results show that the decrease of inflow Mach number and the increase of wedge angle are conducive to the upstream propagation of ODW. In the upstream propagation process, a Mach reflection wave configuration is always established on the wedge surface. For the upstream propagating ODW that cannot detach from the wedge surface by itself, it will stabilize at a point on the wedge surface with an induction region, which is a few times the length of the induction zone of an ideal Zeldovich–von Neumann–Döring (ZND) detonation. Benefiting from the short induction region, the stabilized upstream propagating ODW has extraordinary stability.

A predictor–corrector compact finite difference scheme for Burgers’ equation

Abstract In this paper, a compact predictor–corrector finite difference scheme is proposed to solve the Burgers’ equation. The scheme is based on compact derivatives approximation, by which we get the spatial approximations of first-order derivatives and second-order derivatives with fourth-order accuracy (both for inner nodes and boundary nodes). For the first time derivative item, a two-step predictor–corrector method called MacCormack method is used. Numerical experiments show the scheme is in good agreement with the exact solutions.

Numerical Investigation of the Stability of Rotating Detonation Engines

As the injection total pressure increases, the flow field in the combustion chamber of rotating detonation engine (RDE) becomes complicated and the detonation wave becomes unstable. When the total pressure is high enough, the detonation oscillates periodically and alternates between strong and weak. Under the same injection conditions, no oscillation is observed in two-wave RDE, and the two detonation waves propagate stably in the combustion chamber. The choking ratio of the injection Laval nozzle along the head end is not influenced by the total pressure, the mode of propagation, or the number of detonation waves. And thus the mass flux of RDE can be estimated using the maximum mass flux of the injection Laval nozzle. The specific impulse and thrust of RDE show overall growth as total pressure increases. However, they oscillate with the unstable detonation wave in one-wave RDE at high total pressure.

Finite spectral method based on non-periodic Fourier transform

Abstract Finite spectral method is a conception of pointwise or cellwise local spectral schemes based on non-periodic Fourier transform. The method of non-periodic Fourier transform and two finite spectral schemes are presented. Numerical tests of a wave propagation problem and a shock tube problem are performed.

Numerical Investigation of Spontaneous Formation of Multiple Detonation Wave Fronts in Rotating Detonation Engine

This article presents a three-dimensional (3D) numerical study on rotating detonation engine (RDE), using the premixed stoichiometric hydrogen-air mixture. Different from a conventional numerical setting, intervals are set in the gas intake configuration to bring in effects of nonuniform injection in numerical simulation, which is more semblable to the actual condition in experiments. The simulation successfully shows the spontaneous formation of multiple detonation wave fronts. Discussion is carried out about the factors that affect the phenomenon of multiple detonation wave fronts, which may be helpful to enhance the stability and repeatability of the detonation initiation in RDE experiments. Then subsequently, the simulation result of a typical case is thoroughly described. Three stages of the spontaneous formation of multiple detonation wave fronts after initiation are analyzed. This typical case is also compared to both the conventional simulation and the experimental results to verify its effectiveness.

Numerical Investigation of Different Injection Patterns in Rotating Detonation Engines

Previous numerical simulations of the hydrogen-air rotating detonation engine have been carried out using a simple fuel-injection pattern. This pattern assumes that the fresh gas mixture is injected through every point of the head-wall. This article improves the simulation by discussing four new injection patterns. Parts of the wall are treated as a solid wall in the new patterns. The simulation results show that slits or intervals on the head-walls cause interactions between the detonation waves and combustion products, which affect the formation and stability of detonation. Unstable detonation should be a normal state of rotating detonation engines between stable detonation and failed detonation. The features of the flow fields can be used as a reference for combustion chamber design.

Rotating Detonation Engine Injection Velocity Limit and Nozzle Effects on Its Propulsion Performance

Three-dimensional numerical simulation of a rotating detonation engine (RDE) is carried out in coaxial tube chamber to reveal its physical characteristics. Multi-cycle process of RDE is numerically obtained, and it qualitatively agrees with former experimental results. Some key problems about RDE achievements such as fuel injection, pre-combustion, detonation structure are discussed. At last, we made a propulsion performance analysis about RDE by several different numerical cases.

Rotating Detonation Instabilities in Hydrogen-Oxygen Mixture

Rotating detonation engines are studied more and more widely because of high thermodynamic efficiency and high specific impulse. Rotating detonation of hydrogen and oxygen was achieved in this study. Rotating detonation waves were observed by high speed cameras and detonation pressure traces were recorded by PCB pressure sensors. The velocity of rotating detonation waves is fluctuating during the run. Low frequency detonation instabilities, intermediate frequency detonation instabilities and high frequency detonation instabilities were discovered. They are relevant to unsteady heat release, acoustic oscillations and rotating detonation waves.

Experimental Research on Transition Regions in Continuously Rotating Detonation Waves

Continuously rotating detonation waves of thousands of Hz, indicating the merit of continuously rotating detonation waves that ignite only once to keep working, are experimentally gotten in the combustion chamber designed by Peking University. The steady continuously rotating detonation waves have jarless peak pressures and cycles microcosmicly, showing that during this stage, flux, pressure and temperature of working medium are steady. However, transition regions do exist between two groups of steady continuously rotating detonation waves. Related data of transition regions are fitted to find out the basic rule. The paper also figures out the velocity of ideal detonation waves by C-J theory, and obtains the cycle and number of continuously rotating detonation waves with experimental data.