Papers by Keyword: Shock Wave

Abstract: The purpose of this research is to find propagation rules and development of shock wave caused by roof caving in goaf. The test equipment which was used consisted of high-speed camera and schlieren system. Different kind of roadways have been designed to discuss the propagation rules and development of falling shock wave in different roadway.The results of the experiment indicated that no matter what kind of roadway the shock wave in, the propagation process can roughly divide into two stages. In the first stage, the velocity of shock wave is slower than the second stage and the face of shock wave are clearer, the lines are smoother. But in the second stage, the velocity of shock wave are faster than the first stage and there are many whirls, the lines are more tiny and chaotic. Further research into shock wave caused by roof caving in goaf is necessary.

Abstract: Shock Wave-Boundary Layer Interaction (SBLI) is a phenomenon occurring in high-speed propulsion systems that is highly undesirable. Numerous methods have been tested to manipulate and control SBLI which includes both active and passive flow control techniques. To determine the improvements brought by the flow control techniques, advanced and state-of the-art flow diagnostics and experimental techniques are required, especially when it involves high-speed flows. In this study, a number of advanced flow diagnostics were employed to investigate the effect of micro-vortex generators in controlling SBLI in Mach 5 such as Pressure Sensitive Paints (PSP), Particle Image Velocimetry (PIV), schlieren photography and oil-flow visualization. The flow diagnostics successfully visualized the boundary layer separation and also the improvements brought by the micro-vortex generators.

Abstract: In this paper, blast effect of oil-associated gas in gas injection wells is determined when using air injection displacement, and on this basis, the relevant safety distance is determined also. Numerical simulation is used to calculate the overpressure distribution, explosion energy and TNT equivalence of combustible gas explosion in gas injection wells. Based on shock wave damage criterion, the safety distances in seven levels are obtained, which are personnel minor injuries, severe injuries, death, and destruction of buildings with mild, moderate, severe manage and destroying. Therefore, technical support is provided to accident prevention, emergency and rescue.

Abstract: Using the method of numerical simulations to study fluid dynamic characteristic of underwater vehicle rotary motion, using the N-S equation turbulence model description of the steady rotation of the vehicle, this paper studies the numerical calculation method of aircraft rotating derivative underwater, using UDF programming to produce a stable pressure rotation the flow field, set up an numerical turning basin. Then based on the simulation analysis the influence of the different radius of gyration and different angle of attack on the vehicle motion.

Abstract: The flow passage including supply hole of externally pressurized gas was investigated. The outlet velocity of supply hole, bearing number and supply pressure’s relationship were built. According to supply hole’s speed, supersonic or subsonic model was chosen to calculate bearing clearance’s pressure distribution. Bearing number’s effects on pressure’s distribution was also studied. The calculation result shows that at larger bearing number, supply hole’s speed is harder to be chocked. Both in supersonic and subsonic condition, larger bearing number produces lower pressure loss.

Abstract: Taking into account the issue of configuration or aerodynamic heating, most supersonic and hypersonic flight vehicles have to use the blunt-nosed body. However, in supersonic especially in hypersonic flow the strong bow shock ahead of the blunt nose introduces a rather high shock drag that affects the aerodynamic performance of the vehicles seriously. A spike mounted on a blunt body during its flight pushes the strong bow shock away from the body surface and forms recirculation flow with low pressure ahead of the body surface, and then decreases the drag. The drag reduction effects of spikes in high supersonic and hypersonic flow had been validated through experimental and numerical methods. In order to analyze the influence of the spike on aerodynamic characteristics at low supersonic (M=1.5) flow past blunt-nosed bodies, numerical studies were carried out which included the influence of the spike shape, the analysis of the fluid flow structures and the effect on the aerodynamic characteristics of a blunt body.

Abstract: For understanding the dynamic behavior of open and closed foam subject to a shock wave, this paper through experiments, to gain a deeper understanding of the incidence, reflection and transmission of a shock wave when it interacted with cellular foam. Moreover, by analyzing the loss of the peak overpressure and positive impulse, we were able to respectively know the positive impulse of the incidence, reflection and transmission shock wave. The experimental results indicated that the attenuation capability for foam to the shock wave was caused by the internal friction and deformation of solid phase, which would absorb the energy of the shock wave. From the results we gain an understanding that the mechanical phenomenon of open foam to shock wave are not fully consistent with those of closed foam , while the attenuation of open foam to shock wave is more effective than that of closed foam.

Abstract: Self-similar solution of two-dimensional problem of interaction between a plane longitudinal shock wave and free boundary of elastic half-space is considered. It is suggested that the intensity of this wave is constant. Feasible combinations of wave surfaces which may be generated in elastic medium as a result of such interaction are investigated. Choosing of unique physically admissible mode of deformation propagation from among mathematically possible wave patterns is related to shockwave evolutionary condition and the second law of thermodynamics.

Abstract: The process of shock disturbances in incompressible nonlinear elastic medium is considered. For the case of one-dimensional deformation the two types of plane shock waves are shown, which carry shift deformations in the medium. The properties of these waves are described, their propagation velocities are calculated. The solution of the boundary problem of the interaction of two plane waves with different shear polarization is presented to demonstrate ways of using the obtained results.

Abstract: Supersonic swirling separator has been developed for natural gas dehydration in recent years. Referred to quantities of literature, the working principle and advantages of supersonic swriling separator are discussed. The paper also reviews the research progress of supersonic swirling separator both in developed countries and China in detail. Firstly, the separation technology process from Twister-I to improved Twister-II, and 3s technology in Russia, which comes from aviation technology are reviewed. Secondly, the design of nozzle and cyclone device which are important components for a separator, the simulation of characteristics of gas-fluid two phase flow, and the acquisition of various types of separators and indoor experiments since the project set up in 2003 in China have been introduced. Although there is a considerably long way to go before the industrial application, great achievements such as patents have been made and abundant experimental data and valuable conclusions have been accumulated for further research. Through comparisons and analyses of all these separators, the paper points out both their advantages and disadvantages and the focus of research in the future.