Direct onset detonation initiated by high temperature jets from a pre-combustion tube is investigated numerically. A dispersion-controlled dissipative scheme is adopted to solve Euler equations with axis-symmetric flows implemented with detailed chemical reaction kinetics of the hydrogen-oxygen mixture. For validation and verification purpose, computational results are compared with experimental results. Three regimes of direct detonation initiation, referred to as supercritical, critical and subcritical ones, are demonstrated with numerical analyses from a viewpoint of chain reactions. The regimes are affected by the PDEs geometric configuration. It is recognized that the SWACER mechanism plays an important role in the state transit of chemically reacting flows in which the gradient of chemical radicals presents properly.

A general form of the dispersion-controlled dissipative (DCD) scheme is proposed.An unstructured DCD is constructed and its reliability is demonstrated with numerical simulations.Comparisons of the unstructured results with the second order structured results reveal that the previous resolution is well retained.In order to simulate detonation problems,unstructured DCD is combined with detailed chemical reaction kinetics.The algorithm is used to simulate detonation propagating along a straight duct with or without a wedge.Comparison of the numerical simulations and experiments shows that the algorithm works well in capturing detonation waves.Neither numerical oscillation nor artificial viscosity occurs in practical calculations.

The chemically reacting flow-field of a detonation wave in a bend is simulated by CFD method. The dispersion-controlled dissipative scheme (DCD) is adopted to solve two-dimensional Euler equations implemented with detailed chemical reaction kinetics of hydrogen-oxygen-argon mixture. The fractional step method is applied to treat the stiff problem arising from computation of chemical reaction flow. From the numerical results it is observed that as the curvature of the bend changes,different detonation phenomena occurred along the wall of the bended pipe.If detonation wave propagating through bend with little curvature,the affection of the expansion wave is then stronger to induce the decouple process of the reaction zone and the leading shock.Re-setup of detonation can be completed when the overdriven detonation from another wall reignites the gas mixture in the decoupled zone,and then high overpressure impacts on the bend wall.

In this paper, the improved finite analytic method has been proposed for calculating the fluid flow with the large separation region at the high Reno-Ids number. By this algorism, the complex operations caused by exponential functions and series sum can be removed and a lot of the computational time can be saved. The Renolds number of the flow which can be resolved with this method is about twenty times as much as that of the flow with the or iginal one on the same computational grids. Numerical experiments show that reults obtained with both methods at the same boudary conditions and the same Renolds number are extremely similar and the solutions of the flow at the high Renolds number are satisfactorily.