Characteristics of a typical lifting symmetric supercritical airfoil

The theoretical aerodynamic characteristics of a typical lifting symmetric supercritical airfoil demonstrating its superiority over thenaca 0012 airfoil from which it was derived are presented in this paper. Further, limited experimental results confirming the theoretical inference are also presented. Invited Lecture given at the 3rd Asian Congress on Fluid Mechanics, held in Tokyo during 1–5 September, 1986     

流动空气压差比拟与风电叶片翼型线确定理论的探讨

翼型是风电叶片设计的关键元素,对风电叶片的气动性能、风能转化和利用率都有重要影响。因此,翼型研究一直是风电叶片研究的热点和难点。论文深入分析了流动空气与风电叶片的相互作用,提出了用空气重力比拟其流动前后压差产生的动力的概念,建立了流动空气沿风电叶片流动的能量转化关系,以此为基础推导出了风电叶片翼型线理论公式,并用Xfoil软件对比分析了翼型线理论公式确定的新翼型和BRUXEL36翼型,发现在-2°~6°攻角条件下,新翼型具有较高升阻比,其中在攻角为3°时,新翼型升阻比高出BRUXEL36翼型25左右。论文研究为流动空气与风电叶片相互作用理论及风电叶片翼型线理论的发展提供了新尝试和重要借鉴。     

基于PSI9816智能压力测量系统的应用研究与风洞实验

论述PSI9816智能压力测量系统的工作原理及硬件结构特点,利用LabWindows/CVI开发工具实现系统的模块功能及其工作流程,结合国家863计划"风力机先进翼型族的设计与实验研究"的翼型风洞实验实例,说明了PSI9816智能压力测量系统在风洞实验中的良好应用前景,具有很高的使用价值.     

不可压缩流中二元翼运动的余维二分叉

考虑二元机翼在不可压缩流作用下运动的余维二分叉问题,弹簧的非线性刚度考虑为立方型。化方程为四维一阶微分方程,解析求出了系统发生叉式分叉与HOPF分叉的临界流速的表达式和发生余维二分叉的临界流速和一次刚度。在两个参数平面上研究了系统在余维二分叉点附近的不同区域内平衡点和极限环的稳定性及其个数。最后用数值积分方法给出相应的结果。     

基于N-S方程和序列二次规划的翼型优化设计

实际工程中的翼型设计通常是对某一性能良好的基本翼型进行局部改进以满足特定的工程要求。中将N—S方程流场分析程序和序列二次规划结合起来，发展了一种实用的翼型优化设计方法，用以提高基本翼型在多个设计点、在多种约束条件下的气动性能。由N—S方程计算得到的升力、阻力等气动参数构成目标函数，数值优化程序对其进行最优化。超临界翼型的设计算例表明，中发展的翼型优化方法设计质量高，所需机时少，易于实施，有较大的工程应用价值。     

基于进化算法的压气机叶型多目标优化设计

该文发展了基于进化计算和Navier-Stokes方程求解技术的压气机叶型气动多目标优化设计技术。压气机叶型气动优化设计目标是静压升最大和总压损失最小。文中采用Bezier曲线参数化叶栅几何型线、相应的控制点坐标作为设计变量：压气机叶型气动性能采用Reynolds平均Navier-Stokes方程和Baldwin—Lomax代数紊流模型进行评价；采用实数型多目标进化计算作为优化算法对叶型进行优化设计。优化设计结果得到一组Pareto解集，并且将特定的Pareto解和初始叶型进行详细的气动性能分析比较。优化设计结果证明了该文发展的多目标优化设计技术的有效性和实用性。     

A robust weakly compressible SPH method and its comparison with an incompressible SPH

This paper presents a comparative study for the weakly compressible (WCSPH) and incompressible (ISPH) smoothed particle hydrodynamics methods by providing numerical solutions for fluid flows over an airfoil and a square obstacle. Improved WCSPH and ISPH techniques are used to solve these two bluff body flow problems. It is shown that both approaches can handle complex geometries using the multiple boundary tangents (MBT) method, and eliminate particle clustering‐induced instabilities with the implementation of a particle fracture repair procedure as well as the corrected SPH discretization scheme. WCSPH and ISPH simulation results are compared and validated with those of a finite element method (FEM). The quantitative comparisons of WCSPH, ISPH and FEM results in terms of Strouhal number for the square obstacle test case, and the pressure envelope, surface traction forces, and velocity gradients on the airfoil boundaries as well as the lift and drag values for the airfoil geometry indicate that the WCSPH method with the suggested implementation produces numerical results as accurate and reliable as those of the ISPH and FEM methods. Copyright © 2011 John Wiley & Sons, Ltd.     

Airfoil optimisation for vertical‐axis wind turbines with variable pitch

To advance the design of a multimegawatt vertical‐axis wind turbine (VAWT), application‐specific airfoils need to be developed. In this research, airfoils are tailored for a VAWT with variable pitch. A genetic algorithm is used to optimise the airfoil shape considering a balance between the aerodynamic and structural performance of airfoils. At rotor scale, the aerodynamic objective aims to create the required optimal loading while minimising losses. The structural objective focusses on maximising the bending stiffness. Three airfoils from the Pareto front are selected and analysed using the actuator cylinder model and a prescribed‐wake vortex code. The optimal pitch schedule is determined, and the loadings and power performance are studied for different tip‐speed ratios and solidities. The comparison of the optimised airfoils with similar airfoils from the first generation shows a significant improvement in performance, and this proves the necessity to properly select the airfoil shape.     

Ram‐air kite airfoil and reinforcements optimization for airborne wind energy applications

We present a multidisciplinary design optimization method for the profile and structural reinforcement layout of a ram‐air kite rib. The aim is to minimize the structural elastic energy and to maximize the traction power of a ram‐air kite used for airborne wind energy generation. Because of the large deformations occurring during flight, a fluid‐structure interaction (FSI) routine is included in the optimization, which determines the actual deformed rib geometry and its corresponding aerodynamic characteristics. A qualitative comparison between FSI inclusion and exclusion in the optimization is given. Discrepancies in airfoil profile and structural layout are observed.     

基于动态近似边界条件的气动弹性数值模拟

发展了一种利用欧拉方程计算非定常气动力的数值方法,通过在固定物面边界上满足动态近似边界条件计算出非定常气动力,避免了在每个时间步重新生成网格或需用动网格技术进行网格变形处理过程,提高了计算效率。运用这种方法计算了一系列非定常气动力算例,并与非结构动网格准确边界条件下的欧拉方程解和实验数据进行了比较,进一步分析了翼型俯仰角和马赫数对非定常气动力相对误差的影响。将气动力解算器与结构方程耦合进行气动弹性数值模拟,计算了跨音速具有S型颤振边界的二元气动弹性标准算例-Isogaiwing。算例结果表明,利用动态近似边界条件的欧拉方程具有简便、高效的特点,并能在小振幅情况下得到与精确边界条件精度相当的非定常流场解,还可以用于气动弹性分析。