共查询到5条相似文献,搜索用时 2 毫秒
1.
Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously
generates a shock wave that propagates through the foil and deforms it at a high speed. This high-speed foil deformation can
project dry micro- particles deposited on the anterior surface of the foil at high speeds such that the particles have sufficient
momentum to penetrate soft targets. We used this method of particle acceleration to develop a drug delivery device to deliver
DNA/drug coated microparticles into soft human-body targets for pharmaceutical applications. The device physics has been studied
by observing the process of particle acceleration using a high-speed video camera in a shadowgraph system. Though the initial
rate of foil deformation is over 5 km/s, the observed particle velocities are in the range of 900–400 m/s over a distance
of 1.5–10 mm from the launch pad. The device has been tested by delivering microparticles into liver tissues of experimental
rats and artificial soft human-body targets, modeled using gelatin. The penetration depths observed in the experimental targets
are quite encouraging to develop a future clinical therapeutic device for treatments such as gene therapy, treatment of cancer
and tumor cells, epidermal and mucosal immunizations etc.
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2.
For ideal nozzles, basically two different types of shock structures in the plume may appear for overexpanded flow conditions, a regular shock reflection or a Mach reflection at the nozzle centreline. Especially for rocket propulsion, other nozzle types besides the ideal nozzles are often used, including simple conical, thrust-optimized or parabolic contoured nozzles. Depending on the contour type, another shock structure may appear: the so-called cap-shock pattern. The exact knowledge of the plume pattern is of importance for mastering the engine operation featuring uncontrolled flow separation inside the nozzle, appearing during engine start-up and shut-down operation. As consequence of uncontrolled flow separation, lateral loads may be induced. The side-load character strongly depends on the nozzle design, and is a key feature for the nozzle’s mechanical structure layout. It is shown especially for the VULCAIN and VULCAIN 2 nozzle, how specific shock patterns evolve during transients, and how - by the nozzle design - undesired flow phenomena can be avoided. 相似文献
3.
In the Shock Wave Journal Vol. 2, No. 4 a benchmark test for shock wave reflection over wedges was announced. International
scientists who are interested in shock wave research were invited to participate. The benchmark test aimed at comparison of
various advanced numerical schemes as well as experimental results. During the last three years more than twenty results,
including both CFD and experiments, were collected from all over the world. Efforts contributed by these scientists made the
present benchmark test reach to a standard of the state of the art of the computational fluid dynamics applied to the shock
wave research. However, it was regrettable not to publish all the results collected due to limitation on the available page
number.
Received 5 November 1994 / Accepted 9 September 1996 相似文献
4.
A numerical simulation was performed for the process of formation of single Mach reflection on a wedge by solving a BGK type kinetic equation for the reduced distribution function with a finite difference scheme. The calculations were carried out for a shock Mach number 2.75 and wedge angle 25° in a monatomic gas, which corresponds to the conditions of single Mach reflection in the classical von Neumann theory. The calculations were performed for both diffuse and specular reflection of molecules at the wall surface. It is concluded that the diffuse reflection of molecules at the wall surface or the existence of the viscous or thermal layer is an essential factor for a nonstationary process at the initial stage of Mach reflection. Furthermore, the numerical results for diffuse reflection are found to simulate the experimental results very well, such as a transient process from regular reflection to Mach reflection along with shock propagation.This article was processed using Springer-Verlag TEX Shock Waves macro package 1990. 相似文献
5.
Jiˇí Fürst 《Flow, Turbulence and Combustion》2006,76(4):331-342
The article describes the development of a high order finite volume method for the solution of transonic flow problems. The method is based on a reconstruction procedure similar to the weighted essentially non-oscillatory scheme (WENO). The analysis of accuracy and stability of the method is carried out for the case of smooth data and for simple discontinuity. The computational results demonstrate the performance of the WLSQR method for the solution of several flow problems in 2D and 3D using both structured and unstructured meshes. 相似文献