二维高超声速钝体激波层紫外辐射的实验观察

利用光学多道分析仪，在JF-10氢氧爆轰驱动高焓激波风洞上测量了二维钝体驻点的发射光谱．实验结果表明，在200~280nm的波长范围内，辐射主要来自NO的γ系，同时还分辨出了OH的A-X跃迁、N_2~+的B-X跃迁和烧蚀金属的原子线辐射．

泰氟龙烧蚀对黏性激波层电子密度的影响

采用黏性激波层基本方程组对有无泰氟龙烧蚀两种情况下的钝锥体化学非平衡绕流作了数值求解，以研究泰氟龙烧蚀对流场电子密度的影响规律。算例结果表明：泰氟龙烧蚀确有降低流场电子密度的效应。平衡催化壁工况下这种效应的强度，显著大于非催化壁工况下的强度；远下游截面处的这种效应的强度，显著大于驻点区的强度。此外，通过计算结果分析，对形成上述影响规律的原因作了初步讨论。

Dust-Cloud Structures behind a Shock Wave Moving Over a Deposited Layer of Fine Particles

The present paper investigates dispersed-phase flow structures of a dust cloud induced by a normal shock wave moving at a constant speed over a flat surface deposited with fine particles. In the shock-fitted coordinates, the general equations of dusty-gas

Heating characteristics of blunt swept fin-induced shock wave turbulent boundary layer interaction

An experimental study was conducted on shock wave turbulent boundary layer interactions caused by a blunt swept fin-plate configuration at Mach numbers of 5.0, 7.8, 9.9 for a Reynolds number range of (1.0.similar to 4.7) x 10(7)/m. Detailed heat transfer and pressure distributions were measured at fin deflection angles of up to 30 degrees for a sweepback angle of 67.6 degrees. Surface oil flow patterns and liquid crystal thermograms as well as schlieren pictures of fin shock shape were taken. The study shows that the flow was separated at deflection of 10 degrees and secondary separation were detected at deflection of theta greater than or equal to 20 degrees. The heat transfer and pressure distributions on flat plate showed an extensive plateau region followed by a distinct dip and local peak close to the fin foot. Measurements of the plateau pressure and heat transfer were in good agreement with existing prediction methods, but pressure and heating peak measurements at M greater than or equal to 6 were significantly lower than predicted by the simple prediction techniques at lower Mach numbers.

Two-way coupling model for shock-induced laminar boundary-layer flows of a dusty gas

The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift force. The governing equations are formulated in the dilute two-phase continuum framework with consideration of the finiteness of the particle Reynolds and Knudsen numbers. The full Lagrangian method is explored for calculating the dispersed-phase flow fields (including the number density of particles) in the regions of intersecting particle trajectories. The computation results show a significant reaction of the particles on the two-phase boundary-layer structure when the mass loading ratio of particles takes finite values.

Study of the shock motion in a hypersonic shock system turbulent boundary-layer interaction

Wall pressure fluctuations and surface heat transfer signals have been measured in the hypersonic turbulent boundary layer over a number of compression-corner models. The distributions of the separation shock oscillation frequencies and periods have been calculated using a conditional sampling algorithm. In all cases the oscillation frequency distributions are of broad band, but the most probable frequencies are low. The VITA method is used for deducing large scale disturbances at the wall in the incoming boundary layer and the separated flow region. The results at present showed the existence of coherent structures in the two regions. The zero-cross frequencies of the large scale structures in the two regions are of the same order as that of the separation shock oscillation. The average amplitude of the large scale structures in the separated region is much higher than that in the incoming boundary layer. The length scale of the separation shock motion region is found to increase with the disturbance strength. The results show that the shock oscillation is of inherent nature in the shock wave/turbulent boundary layer interaction with separation. The shock oscillation is considered to be the consequence of the coherent structures in the separated region.

Shock-Induced Dust Cloud Over a Deposit Layer of Fine Particles

The present paper investigates particle density pro les of a dust cloud induced by a normal shock wave moving at a constant speed along a at surface deposited with ne particles. In shock-fixxed coordinates, numerical simulation of ow structures of the carrier- and dispersed- phases was performed for the M = 2 case. The neness and non-uniformity of the particle size are taken into account and their effcts on the dust cloud are discussed in detail.

Direct Numerical Simulation of Shock/Turbulent Boundary Layer Interaction in a Supersonic Compression Ramp

A direct numerical simulation of the shock/turbulent boundary layer interaction flow in a supersonic 24-degree compression ramp is conducted with the free stream Mach number 2.9. The blow-and-suction disturbance in the upstream wall boundary is used to trigger the transition. Both the mean wall pressure and the velocity profiles agree with those of the experimental data, which validates the simulation. The turbulent kinetic energy budget in the separation region is analyzed. Results show that the turbulent production term increases fast in the separation region, while the turbulent dissipation term reaches its peak in the near-wall region. The turbulent transport term contributes to the balance of the turbulent conduction and turbulent dissipation. Based on the analysis of instantaneous pressure in the downstream region of the mean shock and that in the separation bubble, the authors suggest that the low frequency oscillation of the shock is not caused by the upstream turbulent disturbance, but rather the instability of separation bubble.

Effects of Magnetohydrodynamic Interaction-Zone Position on Shock-Wave/Boundary-Layer Interaction

A third-order weighted essentially nonoscillatory and non-free-parameter difference scheme magnetohydrodynamic solver has been established to investigate the mechanisms of magnetohydrodynamics controlling separation induced by an oblique shock wave impinging on a flat plate. The effects of magnetohydrodynamic interaction-zone location on the separation point, reattachment point, separation-bubble size, and boundary-layer velocity profiles are analyzed. The results show that there exists a best location for the magnetohydrodynamic zone to be applied, where the separation point is delayed the farthest, and the separation bubble is decreased up to about 50% in size compared to the case without magnetohydrodynamic control, which demonstrated the promising of magnetohydrodynamics suppressing the separation induced by shock-wave/boundary-layer interactions.

Micro-shock waves generated inside a fluid jet impinging on plane wall

An Nd:glass laser pulse (18 ns, 1.38 J) is focused in a tiny area of about 100-mum diam under ambient conditions to produce micro-shock waves. The laser is focused above a planar surface with a typical standoff distance of about 4 mm, The laser energy is focused inside a supersonic circular jet of carbon dioxide gas produced by a nozzle with internal diameter of 2.9 mm and external diameter of 8 mm, Nominal value of the Mach number of the jet is around 2 with the corresponding pressure ratio of 7.5 (stagnation pressure/static pressure at the exit of the nozzle), The interaction process of the micro-shock wave generated inside the supersonic jet with the plane wall is investigated using double-pulse holographic interferometry. A strong surface vortex field with subsequent generation of a side jet propagating outward along the plane wail is observed. The interaction of the micro-shock wave with the cellular structure of the supersonic jet does not seem to influence the near surface features of the flowfield. The development of the coherent structures near the nozzle exit due to the upstream propagation of pressure waves seems to be affected by the outward propagating micro-shock wave. Mach reflection is observed when the micro-shock wave interacts with the plane wall at a standoff distance of 4 mm, The Mach stem is slightly deflected, indicating strong boundary-layer and viscous effects near the wall. The interaction process is also simulated numerically using an axisymmetric transient laminar Navier-Stokes solver. Qualitative agreement between experimental and numerical results is good.

Interferometric Measurement of Density in Nonstationary Shock Wave Reflection Flow and Comparison with CFD

We present density measurements from the application of interferometry and Fourier transform fringe analysis to the problem of nonstationary shock wave reflection over a semicircular cylinder and compare our experimental measurements to theoretical results from a CFD simulation of the same problem. The experimental results demonstrate our ability to resolve detailed structure in this complex shock wave reflection problem, allowing visualization of multiple shocks in the vicinity of the triple point, plus visualization of the shear layer and an associated vortical structure. Comparison between CFD and experiment show significant discrepancies with experiment producing a double Mach Reflection when CFD predicts a transitional Mach reflection.

An investigation of electromagnetic wave propagation in plasma by shock tube

This paper presents the electromagnetic wave propagation characteristics in plasma and the attenuation coefficients of the microwave in terms of the parameters n(e), v, w, L, w(b). The phi800 mm high temperature shock tube has been used to produce a uniform plasma. In order to get the attenuation of the electromagnetic wave through the plasma behind a shock wave, the microwave transmission has been used to measure the relative change of the wave power. The working frequency is f = (2 similar to 35) GHz (w = 2pif, wave length lambda = 15 cm similar to 8 mm). The electron density in the plasma is n(e) = (3 x 10(10) similar to 1 x 10(14)) cm(-3). The collision frequency v = (1 x 10(8) similar to 6 x 10(10)) Hz. The thickness of the plasma layer L = (2 similar to 80) cm. The electron circular frequency w(b) = eB(0)/m(e), magnetic flux density B-0 = (0 similar to 0.84) T. The experimental results show that when the plasma layer is thick (such as L/lambda greater than or equal to 10), the correlation between the attenuation coefficients of the electromagnetic waves and the parameters n(e), v, w, L determined from the measurements are in good agreement with the theoretical predictions of electromagnetic wave propagations in the uniform infinite plasma. When the plasma layer is thin (such as when both L and lambda are of the same order), the theoretical results are only in a qualitative agreement with the experimental observations in the present parameter range, but the formula of the electromagnetic wave propagation theory in an uniform infinite plasma can not be used for quantitative computations of the correlation between the attenuation coefficients and the parameters n(e), v, w, L. In fact, if w < w(p), v(2) much less than w(2), the power attenuations K of the electromagnetic waves obtained from the measurements in the thin-layer plasma are much smaller than those of the theoretical predictions. On the other hand, if w > w(p), v(2) much less than w(2) (just v approximate to f), the measurements are much larger than the theoretical results. Also, we have measured the electromagnetic wave power attenuation value under the magnetic field and without a magnetic field. The result indicates that the value measured under the magnetic field shows a distinct improvement.

Shock slip-relations for thermal and chemical nonequilibrium flows

This paper appears to be the first where the multi-temperature shock slip-relations for the thermal and chemical nonequilibrium flows are derived. The derivation is based on analysis of the influences of thermal nonequilibrium and viscous effects on the mass, momentum and energy flux balance relations at the shock wave. When the relaxation times for all internal energy modes tend to sere, the multi-temperature shock slip-relations are converted into single-temperature ones for thermal equilibrium hows. The present results can be applied to flows over vehicles of different geometries with or without angles of attack. In addition, the present single-temperature shock slip-relations are compared with those in the literature, and Some defects and limitations in the latter are clarified.

Reflection of shock-wave in pur foam from rigid wall

Keller proposed that a building, a mechanical installation or a body wrapped bya layer of foam plastics may be an efficient means for protection from damage ofblast wave. However, the practical effect was beyond expectation. For example, agunner wearing the foam plastics-padded waistcoat was injured more seriously by theblast wave from a muzzle. Monti took the foam plastics as homogeneous two-phasemedium and analyzed it with the theory of dusty flow. The obtained results showthat the peak pressure behind the reflected shock wave from rigid wall with foamcoat exceeds obviously that without foam coat under the same condition. Gel'fand,Patz and Weaver made experimental observations by means of shock tubes and veri-