Anomalous particle transport in the heliosphere

The transport of energetic particles in the presence of magnetic turbulence can exhibit a variety of regimes different from the standard quasilinear diffusion. Here we discuss a number of solar and space problems where nonquasilinear diffusion is found, and then we illustrate anomalous transport regimes, for which the mean square deviation grows nonlinearly with time. In particular, we concentrate on superdiffusive regimes, and show what is the theoretical framework which is to be used to describe superdiffusion. We discuss the results of numerical simulations which show that superdiffusive and subdiffusive regimes are possible, and describe data analyses which allow to single out the superdiffusive transport from the observation of energetic particle profiles upstream of interplanetary shocks. The implications of superdiffusion on the efficiency of wave particle interactions are also discussed.     

老子深邃的贵身思想

老子关注人的一项重要内容就是要确定身与物谁贵谁轻。他主张贵身，反对以物役身；人是目的，物为手段；人以身为贵，依道贵身；贵身有道。     

Three dimensional investigation of the shock train structure in a convergent–divergent nozzle

Three-dimensional computational fluid dynamics analyses have been employed to study the compressible and turbulent flow of the shock train in a convergent–divergent nozzle. The primary goal is to determine the behavior, location, and number of shocks. In this context, full multi-grid initialization, Reynolds stress turbulence model (RSM), and the grid adaption techniques in the Fluent software are utilized under the 3D investigation. The results showed that RSM solution matches with the experimental data suitably. The effects of applying heat generation sources and changing inlet flow total temperature have been investigated. Our simulations showed that changes in the heat generation rate and total temperature of the intake flow influence on the starting point of shock, shock strength, minimum pressure, as well as the maximum flow Mach number.     

Mach reflection in steady supersonic flow considering wedge boundary-layer correction

Mach reflection in steady supersonic flow is an important phenomenon having received extensive studies, among which simplified theoretical models to predict the size of Mach stem and other flow structure are of particular interest. Past efforts for such models were based on inviscid assumption while in real cases the flow is viscous. Here in this paper we consider the influence of wedge boundary layer on the Mach stem height. This is done by including a simplified boundary layer model into a recently published inviscid model. In this viscous model, the wedge angle and the trailing edge height, which control the Mach stem height, are replaced by their equivalent ones accounting for the displacement effect of the wedge boundary layer, with the boundary layer assumed to be laminar or fully turbulent. This viscous model is shown to compare well with numerical results by computational fluid dynamics and gives a Mach stem height as function of the Reynolds number and Mach number. It is shown that due to the viscous effect, the Mach stem height is increased, through increasing the effective wedge angle.     

Interaction mechanisms of shock waves with the boundary layer and wakes in a highly-loaded NGV using hybrid RANS/LES

Accurate predictions of Shock Waves and Boundary Layer Interaction (SWBLI) and strong Shock Waves and Wake Vortices Interaction (SWWVI) in a highly-loaded turbine propose challenges to the currently widely used Reynolds-Averaged Navier-Stokes (RANS) model. In this work, the SWBLI and the SWWVI in a highly-loaded Nozzle Guide Vane (NGV) are studied using a hybrid RANS/LES strategy. The Turbulence Kinetic Energy (TKE) budget and the Proper Orthogonal Decomposition (POD) method are used to analyze flow mechanisms. Results show that this hybrid RANS/LES method can obtain detailed flow structures for flow mechanisms analysis. Strong shock waves induce boundary layer separation, while the presence of a separation bubble can in turn lead to a Mach reflection phenomenon. The shock waves cause trailing-edge vortices to break clearly, and the wakes, in turn, can change the shocks intensity and direction. Furthermore, the Entropy Generation Rate (EGR) is used to analyze the irreversible loss. It turns out that the SWWVI can reduce the flow field loss. There are several weak shock waves in the NGV flow field, which can increase the irreversible loss. This work offers flow mechanisms analysis and presents the EGR distribution in SWBLI and SWWVI areas in a transonic turbine blade.     

Simulator of pyroshock environment and effect rules of its adjustable parameters

During the launching of spacecraft, the on-board devices will undergo a series of pyroshock environments. In order to verify the reliability of these devices under these pyroshock environments, all of them are needed to take the shock test before launching. This paper has carried out an in-depth research on the simulation method of the pyroshock based on the true explosive excitation. In this study, a simulator containing multiple adjustment parameters is presented and the safety is considered by the design of the protective cover. And the working process of this setup is simulated with the explicit dynamic codes LS-DYNA. What’s more, the effects of the adjustment parameters on the three factors of shock Response Spectrum (SRS) of the resonant board are explored carefully. The rules achieved in this paper are verified by a typical example. The results indicate that the improved simulator can avoid the danger of explosive and make full use of the advantage of actual explosive excitation. And the test condition can be quickly realized at the simulator according to the effect rules of the three adjustable parameters.     

类X-38升力体运载器气动布局概念设计

开展升力体运载器的气动布局概念设计研究,利用二次曲线横截面及模线设计方法,提出一种类X-38升力体运载器气动外形,进行机体的优化和控制舵的匹配设计,研究飞行器的气动特性和操纵效率问题。研究表明,该方案可以获得较高的配平升阻比及配平攻角,有较高的容积效率和机动控制效率,可以作为未来航天运载器的潜在可行方案。     

Interference-free wind tunnel testing of jet propelled missiles

Wind tunnel evaluation of the aerodynamic interaction effects between plume and the external flow past the missile body including the wake boundary (“slipstream”) over powered flight envelopes of rocket propelled vehicles can be greatly facilitated — or even made possible — by a methodology replacing the hot propellant by cold, inert gases. Model nozzle design is based on the second order matching of plume geometry and first order modeling of plume stiffness. Since modeled nozzles will have larger throat radii than the prototypes, one can use sting-supported, sting-fed model installations thus eliminating aerodynamic interference effects due to struts. The concepts of simulated altitude and simulated full-scale Reynolds Number greatly reduce wind tunnel occupancy time. Computer programs, covering all steps of evaluating prototype nozzle performance, model sting nozzle design, model test evaluation and interpretation have been developed. The modeling methodology is supported by experimental results obtained in an induction wind tunnel at the FFA, Bromma, Sweden and in the 16 T and VKF-A altitude tunnels at AEDC, Tullahoma, Tenn.     

大尺寸测量系统配置中包络性与可达性分析

构建了包络性和可达性分析的原理与公式，定量判定当前测量设备空间位置是否合理，为实现在大尺寸测量方案规划阶段对测量设备的可行空间进行快速有效的规划提供依据。阐述了大尺寸测量系统总体架构与阶段任务划分，定义了包络性与可达性的输入输出关系。论述了包络性与可达性的原理与公式，包括可测量体素和外包络体的定义、数学模型和推导公式以及判定公式。最后，在CATIA环境下开发包络性和可达性分析工具，并以机翼翼肋为例，对该翼肋上待测关键特征进行包络性和可达性仿真分析。仿真结果表明，该包络性与可达性分析的原理与公式是可行的。     

后掠翼身交接区流动结构及参数影响研究

在水槽中利用激光片光源及荧光素钠染色液显示方法 ,研究了圆柱、机翼与平板交接区及后掠圆柱、后掠机翼变迎角情况下的干扰流场结构、特性及参数影响规律。结果表明 ,除Re数之外模型迎角、后掠角等参数对干扰区马蹄涡特性有很大影响。研究发现后掠圆柱及后掠机翼在一定条件下存在一类既不同于马蹄涡也不同于卡门涡的空间稳定发展的三维旋涡系即背涡。讨论了干扰背涡产生的机制及其与马蹄涡的相互关系。