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The fluidal jet turbulator has been a novel perturbation generator in the pulse-detonation engines research field for the past few years. In this paper, an experiment is performed to study the deflagration to detonation transition (DDT) process in a detonation chamber with a reactive transverse methane-oxygen mixture jet in crossflow (JICF). The jet injection arrangement is fundamentally investigated, including single jet and various double jets patterns. Corresponding two-dimensional direct numerical simulations with a multistep chemical kinetics mechanism are employed for analyzing details in the flow field, and the interaction between the vortex and flame temporal evolution is characterized. Both the experiments and simulations demonstrate that the JICF can distinctly accelerate flame propagation and shorten the DDT time and distance. The vortex stream induced by the jet distorts and wrinkles the flame front resulting in local flame acceleration. Moreover, the double jet patterns enhance flame acceleration more than the single jet injection because of the intrinsic counterrotating vortex pairs and enhanced turbulence intensity.

A new hypersonic inlet named three-dimensional section controllable internal waverider inlet is presented in this paper to achieve the goal of section shape geometric transition and complete capture of the upstream mass. On the basis of the association between hypersonic waverider airframe and streamtraced hypersonic inlet, the waverider concept is extended to yield results for the internal flows, namely internal waverider concept. It is proven theoretically that not osculating cones but osculating axisymmetric theory is appropriate for the design of section controllable internal waverider inlet. And two design methods out of the internal waverider concept are proposed subsequently to construct two inlets with specific section shape request, triangle to ellipse and rectangle to ellipse ones. The calculation results show that the inlets are capable of keeping their shock structures and the main flow characteristics exactly as their derived flowfield. Further, the inlets successfully capture all the upstream mass despite their complicated cross-section transitions. It is believed that the concept proposed explores a new way of designing three-dimensional hypersonic inlets with special demand of section shape transition. However, the detailed flow characteristic and the performance of the internal waverider inlets are still under investigation. section controllable, internal waverider, hypersonic inlet, osculating flow, all mass captureThe new design concept of inward turning hypersonic inlet [1] has received considerable attention in the research community of hypersonic inlet design. It has been proven lately that the inlet holds the potential of better aerodynamic performance than those with conventional compression styles. For example, the JAWS [2,3] developed by U.S. Air Force Research Laboratory (AFRL) got a 24.87% net thrust addition compared with a typical two-dimensional planar hypersonic inlet. In June 2007, the hypersonic collaborative Australia/United States experiment (HyCAUSE) [4,5] flight experimental scramjet engine validated the performance of another three-dimensional inward turning hypersonic inlet. Recently, Lockheed has announced that their next generation hypersonic aircraft, Force Application and Launch from CONUS (FALCON) [6,7] , will also contain two modules of the innovative three-dimensional inward turning inlet. In the critical reviews [8][9][10] , Billig from Johns Hopkins University, stated the foundation of the concept, detailed design method as well as the performance of streamtraced inlet, an important member of the inward turning inlets. More significantly, it is believed [10] that the threedimensional inward turning inlet will lead the hypersonic inlet research in the future and consequently bring about a revolution in scramjet propulsion technology.The ongoing three-dimensional hypersonic inlets include Busemann, JAWS, modular waverider, rectangular to elliptical shape transition (REST) and rectangular to circular shape transition (RCST) ones. According to their integration manner...

The physical characteristics inside shock waves with nonequilibrium molecular motion are difficult to describe using conventional macroscopic methods. In this paper, nonequilibrium hydrodynamic and thermodynamic effects caused by the strong nonequilibrium molecular velocity distribution at a shock wave are studied using a mesoscopic kinetic approach. This approach is based on a lattice Boltzmann method and a kinetic nonequilibrium method. The former adopts a compressible double-distribution-function model with separated density and total energy distribution functions. The latter represents the nonequilibrium effects through nonequilibrium kinetic moments based on the nonequilibrium molecular velocity distribution. The nonequilibrium effects in the steady state and the process of the formation of a regular reflection shock wave are presented. Nonequilibrium effects inside the shock wave are further investigated. First, the curvature pattern during the formation of a regular reflection shock wave is addressed. The curvature characteristic leads to distinct features of nonequilibrium effects compared with the linear pattern. A vector-based approach for visualizing nonequilibrium effects is proposed to study the curvature pattern. Second, the influence of viscosity on nonequilibrium effects, which is related to the average collision time among molecules at the shock wave, is explored. The results obtained in this paper provide mesoscopic physical insight into the flow mechanisms occurring in shock waves.

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