轴流式压气机进口导叶滞后角的计算

根据一系列平面叶栅风洞试验的结果,确定了轴流式压气机中可转导叶和可变尾缘导叶的气动特性,从而总结出它们的滞后角按卡特公式计算时适用的范围和必须进行的修正。     

爆炸成形弹丸技术现状与发展

介绍了形成高速、飞行稳定且后效好的爆炸成形弹丸的基本设计准则以及几种形成尾翼的结构设计方法。通过总结现有爆炸成形弹丸技术的实验、数值模拟和具体应用实例．提出了爆炸成形弹丸技术的发展方向和新的应用前景。     

沸腾炉旋风燃尽室的冷态及热态试验研究

对沸腾炉旋风燃尽室进行了冷态模型试验和热态燃烧试验。在冷态试验中,对旋风燃尽室的空气动力场特性以及颗粒运动、分布和分离情况进行了观测。在热太燃烧试验中,测算了的燃烧效率。试验结果表明,采和旋风燃尽室来提高沸腾炉的燃烧效率是可行的。     

Unsteady rotor-stator interaction in high speed compressor and turbine stages

The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have been far fewer works which give results of blade row interaction within high speed cases. Two cases are related in this paper. First, the effects of an incoming wake on the rotor flow field of a transonic compressor are analyzed. The blade row interaction proved to be positive regarding the total pressure ratio, but negative regarding the losses. The second case concerns a transonic turbine. Particular emphasis is placed on the assessment of the deterministic correlations included in the Averaged Passage Equation System.     

Computational fluid dynamics simulation of the aerodynamics of a high solidity,small‐scale vertical axis wind turbine

A computational fluid dynamics simulation was performed for a small‐scale, high solidity (σ = 0.48) H‐type Darrieus vertical axis wind turbine. Two‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations were solved for the turbine numerical model, which has a large stationary domain and smaller rotating subdomain connected by a sliding mesh interface. The simulation results were first validated against steady‐state airfoil data. The model was then used to solve for three rotating blades with constant ambient flow velocity (Re = 360,000) over numerous blade speed ratios. The high solidity and the associated low blade speed ratio and rotational speed of the turbine result in complex flow–blade interaction mechanisms. These include dynamic stall resulting in vortex shedding, vortex impingement on the source blade and significant flow momentum extraction causing reduced power production from the downstream blade pass. Copyright © 2011 John Wiley & Sons, Ltd.     

面向空气动力学优化的电动汽车造型设计研究

从汽车造型设计的比例、容积、曲面、细节4个层级出发,逐层分析了未来具有优秀空气动力学性能的电动汽车在比例、容积、曲面、细节中应该具有的特点。提出了要设计未来具有优秀空气动力学性能的电动汽车应该打破过去的"汽车式"的比例容积安排,改变过去"大功率高能耗"的曲面语言,转而探索符合电动汽车设计理念的环保、高效、自然的曲面语言,并且在细节上辅以与电动汽车比例、容积和曲面统一的、合理体现电动汽车技术特点的细节。     

导气与枪管浮动混合式自动机动力学特性研究

为了研究导气与枪管浮动混合式自动机在高初速榴弹发射器上应用的可行性及通过调节导气装置结构参数匹配枪管组件与枪机框组件后坐能量达到降低武器系统后坐力的目的,基于气体动力学理论和热力学理论,推导考虑热量散失及枪管浮动作用的内弹道和导气装置气流问题的基本方程组。利用该计算模型对高初速榴弹发射器发射动力学进行仿真,得出武器系统自动机运动特性曲线及后坐力随时间变化的曲线。将仿真结果与实验结果进行对比,验证模型的正确性。探讨导气装置导气孔直径、导气孔开孔位置、导气室初始容积结构参数对导气室气体压力变化的影响规律,并分析其对自动机速度曲线及后坐力的影响。在完成自动机自动循环的前提下,采用导气与枪管浮动混合式自动机可将武器的最大后坐力控制在1 100 N内,实现武器低后坐发射。     

单风机矿井通风网络非稳定流动模型及MATLAB数值模拟

根据井巷风流一维非稳定流动的微分方程和巷道内风流非稳定流动的数学模型,基于矿内空气动力学和矿井通风网络理论,建立了单风机矿井通风网络非稳定流动的数学模型。应用刚体理论和有限差分法,对模型进行求解,并利用MATLAB模拟了风机切断电源后分支风量的变化,得到了分支风量随时间变化的曲线。     

An experimental investigation on the wake interferences among wind turbines sited in aligned and staggered wind farms

An experimental investigation was conducted for a better understanding of the wake interferences among wind turbines sited in wind farms with different turbine layout designs. Two different types of inflows were generated in an atmospheric boundary layer wind tunnel to simulate the different incoming surface winds over typical onshore and offshore wind farms. In addition to quantifying the power outputs and dynamic wind loads acting on the model turbines, the characteristics of the wake flows inside the wind farms were also examined quantitatively. After adding turbines staggered between the first 2 rows of an aligned wind farm to increase the turbine number density in the wind farm, the added staggered turbines did not show a significant effect on the aeromechanical performance of the downstream turbines for the offshore case. However, for the onshore case, while the upstream staggered turbines have a beneficial effect on the power outputs of the downstream turbines, the fatigue loads acting on the downstream turbines were also found to increase considerably due to the wake effects induced by the upstream turbines. With the same turbine number density and same inflow characteristics, the wind turbines were found to be able to generate much more power when they are arranged in a staggered layout than those in an aligned layout. In addition, the characteristics of the dynamic wind loads acting on the wind turbines sited in the aligned layout, including the fluctuation amplitudes and power spectrum, were found to be significantly different from those with staggered layout.     

Computational observations of the tip loss mechanism experienced by horizontal axis rotors

Blade resolved computations of two different horizontal axis rotors are conducted to investigate the tip loss mechanism experienced by horizontal axis rotors. The tip loss mechanism specifically refers to the effect of the vorticity that is shed from the outboard blade sections, which results in the blade loading dropping off as the tip is approached. In this paper, the shed vorticity is shown to induce a downwash at the rotor plane and spanwise flow accelerations along the blade surfaces. While the downwash reduces the angle of attack of the approach flow, the spanwise flow accelerations lead to additional momentum transport along the blade. This spanwise momentum transport reduces the magnitude and changes the distribution of the static pressure developed on the pressure and suction surfaces of the outboard blade sections. As a result of this modification, the torque producing force drops off faster than the thrust producing force as the tip is approached, resulting in a rotation of the net force vector towards the streamwise direction. This anisotropy must be accounted for by tip flow corrections if the loading on the outboard blade sections is to be computed with sufficient accuracy. In addition, it is also shown that changes in the static pressure distribution cannot be accurately approximated by only modifying the angle of attack of the approach flow, as this would lead to blade loading changes that are inconsistent with the observed behaviour of the lift and drag coefficients on the outboard blade sections.