夹层结构复合材料翼型件模压工艺

对夹层结构复合材料翼型件的成型工艺进行了选择、试验,确定了夹层结构复合材料翼型件的成型方案,从而使翼型件具有优异的外形和性能。     

面向性能的压气机叶片铣削加工误差分析及统计

为提高航空发动机压气机叶片的加工质量,对其铣削加工中的质量影响因素进行了分析,包括加工前工艺规划及几何造型等因素、加工过程中变形与稳定性等问题以及加工后的残余应力变形等。针对必然存在的加工误差,提出了一种概率统计方法,并在此基础上对于影响气动性能的叶型关键几何区域,建立了有关轮廓误差和叶型参数误差的统计分析方法。借助于气动性能试验,获得了稳定工况下关键参数的误差分布,从而为指导叶片的实际铣削加工提供了理论依据。     

Optimization and design of an aircraft's morphing wing-tip demonstrator for drag reduction at low speed,Part Ⅰ–Aerodynamic optimization using genetic,bee colony and gradient descent algorithms

In this paper, an ‘in-house' genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The algorithm's performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods,namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing wing-tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.     

Rotor airfoil aerodynamic design method and wind tunnel test verification

Well-designed airfoil is very important for high-performance rotor. This paper developed an efficient multi-objective and multi-constraint optimization design system for rotor airfoils based on RANS analysis, and verified the performance of the optimized airfoil. Using CRA09-A as the baseline rotor airfoil, the CRA09-B optimized rotor airfoil was designed successfully. Combined with the foundation of high-precision rotor airfoil stationary test technology, the CRA09-B and CRA09-A rotor airfoils were tested in the S3MA high-speed wind tunnel of ONERA. In order to correct the aerodynamic data, a single parameter linear wall pressure method is used to consider the tunnel effects. The results indicate that multi-objective and multi-constraint optimization design method developed in this study is reliable, and that CRA09-B optimized airfoil provides better stationary performance than CRA09-A airfoil in terms of maximum lift coefficient and lift-to-drag ratio.     

Aerodynamic shape optimization for alleviating dynamic stall characteristics of helicopter rotor airfoil

In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming(SQP) method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation(CST) method, and the C-topology body-fitted mesh is then automatically generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes(RANS) equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower–upper symmetric Gauss–Seidel(LU-SGS) is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart–Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the optimized airfoil under unsteady conditions are obviously weakened, and the dynamic stall characteristics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil.     

基于遗传算法与近似模型的全局气动优化方法

开发了基于精英保留策略与小生境技术的求解有约束优化问题的改进遗传算法,并用一多峰值有约束函数对其寻优能力进行了测试。为了降低气动优化设计时间,提出了集成实验设计、三维粘性流场求解程序、二次多项式近似模型、改进遗传算法的具有全局寻优能力的三维气动优化设计体系。采用该方法对NASA Rotor37动叶片叶型进行了以绝热效率最大为目标的优化设计,优化后叶片绝热效率提高1.1%。该结果表明了本优化设计体系省时、高效的特点。     

Aerodynamic performance enhancement of co-flow jet airfoil with simple high-lift device

The present study performed a numerical investigation to explore the performance enhancement of a co-flow jet (CFJ) airfoil with simple high-lift device configuration, with a specific goal to examine the feasibility and capability of the proposed configuration for low-speed take-off and landing. Computations have been accomplished by an in-house-programmed Reynolds-averaged Navier-Stokes solver enclosed by k-ω shear stress transport turbulence model. Three crucial geometric parameters, viz., injection slot location, suction slot location and its angle were selected for the sake of revealing their effects on aerodynamic lift, drag, power consumption and equivalent lift-to-drag ratio. Results show that using simple high-lift devices on CFJ airfoil can significantly augment the aerodynamic associated lift and efficiency which evidences the feasibility of CFJ for short take-off and landing with small angle of attack. The injection and suction slot locations are more influential with respect to the aerodynamic performance of CFJ airfoil compared with the suction slot angle. The injection location is preferable to be located in the downstream of the pressure suction peak on leading edge to reduce the power expenditure of the pumping system for a relative higher equivalent lift-to-drag ratio. Another concluded criterion is that the suction slot should be oriented on the trailing edge flap for achieving more aerodynamic gain, meanwhile, carefully selecting this location is crucial in determining the aerodynamic enhancement of CFJ airfoil with deflected flaps.     

Transit time difference and equal or non-equal transit time theory for airfoils with lift

The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically. We show that, under thin airfoil assumption and for potential flow, the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference. An analysis of transit time differe...     

Experimental investigation of shock-buffet criteria on a pitching airfoil

An experimental investigation of the shock-buffet phenomenon subject to unsteady pitching supercritical airfoil around its quarter chord has been conducted in a transonic wind tunnel. The model was equipped with pressure taps connected to the fast response pressuretransducers. Measurements were conducted at different free-stream Mach number from 0.61 to0.76. The principle goal of this investigation was to experimentally discuss the shock-buffet criterion over a SC(2)-0410 supercritical pitching ...