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排序方式: 共有300条查询结果,搜索用时 390 毫秒
1.
Rayleigh-Brillouin light scattering experiments were performed on gelatin gels in order to obtain the (hypersonic) sound velocity and sound attenuation as a function of gelatin concentration. The results show that in the high frequency regime there is a strong coupling in the gel between the dynamics of the network and that of the fluid. The network sound velocity varies with
1/2. Sound attenuation increases with increasing gelatin concentration. 相似文献
2.
A sharp‐interface immersed boundary framework for simulations of high‐speed inviscid compressible flows 下载免费PDF全文
Shuvayan Brahmachary Ganesh Natarajan Vinayak Kulkarni Niranjan Sahoo 《国际流体数值方法杂志》2018,86(12):770-791
A new finite‐volume flow solver based on the hybrid Cartesian immersed boundary (IB) framework is developed for the solution of high‐speed inviscid compressible flows. The IB method adopts a sharp‐interface approach, wherein the boundary conditions are enforced on the body geometry itself. A key component of the present solver is a novel reconstruction approach, in conjunction with inverse distance weighting, to compute the solutions in the vicinity of the solid‐fluid interface. We show that proposed reconstruction leads to second‐order spatial accuracy while also ensuring that the discrete conservation errors diminish linearly with grid refinement. Investigations of supersonic and hypersonic inviscid flows over different geometries are carried out for an extensive validation of the proposed flow solver. Studies on cylinder lift‐off and shape optimisation in supersonic flows further demonstrate the efficacy of the flow solver for computations with moving and shape‐changing geometries. These studies conclusively highlight the capability of the proposed IB methodology as a promising alternative for robust and accurate computations of compressible fluid flows on nonconformal Cartesian meshes. 相似文献
3.
本文在高超声速脉冲式风洞内对基于纳米示踪的平面激光散射技术(nano-based planar laser scattering, NPLS)的应用进行了探索, 并在此基础上对平板边界层流动结构的精细测量进行了研究. 试验来流Ma=7.3, 总压4.8 MPa, 总温680 K. 通过时序的分析和调试, 对各分系统实现了高精度的同步控制; 定量的粒子注入及混合, 实现了粒子的均匀撒播, 对主流获得了均匀的显示效果; 对于边界层流动, 获得了精细的瞬态流动结构图像, 显示了层流到湍流的转捩过程, 并分析了其时空演化特性. 相似文献
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随着临近空间高超声速技术的迅猛发展和临近空间高超声速导弹的装备使用,新的军事威胁已成为现实。由于临近空间高超声速导弹飞行弹道低且具有机动飞行的特点,需要对它进行实时探测跟踪才有可能对其飞行弹道进行预测。受地球曲率等因素的影响,地面雷达系统对临近空间高超声速导弹的探测距离有限,且组网探测对雷达数量需求庞大,因此卫星探测是一种较好的手段。对美国当前大力发展的海陆军通用型高超声速滑翔体(Common Hypersonic Glide Body, C-HGB)的红外辐射特性进行了初步分析,并结合高轨红外预警卫星的探测能力,初步分析了预警卫星对处于滑翔飞行阶段的C-HGB的可探测性。结果表明,当前的高轨红外预警卫星难以实现对处于滑翔段的C-HGB的探测,所以需要改进卫星红外探测系统或者组建低轨卫星星座。 相似文献
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The evolution of 2-D disturbances in hypersonic boundary layer with Mach number 6,8, and 10 was investigated numerically by
three different numerical schemes. At the entrance, second mode T-S waves with different amplitudes were introduced, and the
relation between the Mach number and the amplitude of the disturbance when shocklets started to appear was investigated. By
comparing the disturbance velocity profiles with those provided by linear stability theory, the effects of shocklets on flow
structures were also investigated. 相似文献
9.
The aerodynamic characteristics of cone-sphere models are studied at Mach numbers M = 6, 8.4, and 12 to 13 over a wide Reynolds number range. Models of a braking device (sphere) were connected with a load (frustum of a cone) by means of shrouds. The dependences of the aerodynamic coefficients C x and C y on the angle of attack α were obtained for different relative dimensions of the load and the braking device, shroud lengths, and Mach and Reynolds numbers. The effect of the above-mentioned parameters on the aerodynamic characteristics of the models is analyzed. The C x (ReD) dependences of load-parachutemodels in a symmetric flow are determined over the wide Mach and Reynolds number ranges 6 ≤ M ≤ 13 and 3 · 103 ≤ ReD ≤ 3 · 106. 相似文献
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