气垫船推进装置气动力优化与模型试验研究

以某气垫船推进装置为研究对象,以提高其推进效率为目标,开展推进装置气动力理论优化设计与风洞试验验证工作。首先,基于B样条参数化方法,对推进装置的导管外形进行参数化建模,获得B样条控制参数,并将其定义为优化设计变量;其次,基于试验设计方法DOE、B样条参数化方法和数值仿真方法,开展导管气动力优化设计,形成理论优化方案。最后,设计制作缩尺模型,开展风洞试验,进一步验证理论优化方案的可信度。研究表明:导管外形对其自身以及整个推进装置的气动性能影响明显;通过精细设计导管外形,可以获得更高的推进效率;优化导管外形之后,气垫船推进装置的推进效率明显提升,其中额定功率下的总推力可提高约3%。

基于遗传算法的微型飞行器气动力优化设计

本文以固定机翼式微型飞行器的翼型气动力优化设计为研究背景,在105量级的低雷诺数范围内,把遗传算法与Navier-Stokes方程数值解法相结合,建立了一种以实数编码为基础的自适应算法模型。在基准翼型的基础上,结合锦标赛选择、部分交叉以及自适应变异算子,对翼型进行了升阻比气动力优化设计,并设计了一种高效的复制算子来提高算法的稳定性和计算效率。优化后的翼型升阻比提高显著,表明该算法对低雷诺数翼型的气动外形设计合理有效。

多段翼型气动力优化设计的多标准高效进化算法

本文分别结合基因算法与博弈论中的竞争型Nash对策及分级型Stackelberg对策构造了多标准高效进化算法,并对二维三段翼型成功地进行了多标准位置增升优化。基因算法在合适地选择了基因操作算子后可以得到全局最优解,博弈论的引入使得传统基因算法具备了无人工干预的多标准优化算法,并且这一优化过程接近于实际翼型工程气动力设计情况。应用本文的方法成功地对三段翼型进行了不同气动条件下的缝翼与襟翼的位置组合优化,最后给出了优化算例,并对两种算法进行了对比。

气动力优化EFP性能的模拟

在作用的速度范围内，我们用数值模拟的办法研究了气动力优化条件下铁ＥＦＰ的侵彻和穿透性能。介绍通过三维纳维耶—斯托克斯（Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ）编码和二维、三维欧拉（Ｅｕｌｅｒｉａｎ）流体编码预报外弹道和终点弹道的例子。对三个ＥＦＰ构形在额定马赫（Ｍａｃｈ）数６和攻角范围０°～５°之间进行气动力预报。终点弹道学评定单块有限钢靶的特征。对撞击速度范围在１５００ｍ／ｓ～２５００ｍ／ｓ之间以及倾角达２０°的侵彻状态进行模拟。分析和讨论位于弹丸几何形状上的气动力要求与它的终点弹道性能之间的一致性。

基于非结构网格离散型伴随方法的翼型优化

发展实现了基于非结构网格离散型伴随方法的气动力优化技术并将其应用于翼型优化。针对以往伴随模型只考虑流场伴随方程而使梯度计算量仍与设计变量数目相关的问题,研究了基于目标函数计算全过程的伴随模型,通过对优化问题整体进行线化、转置运算从而得到完整的伴随模型,实现了梯度计算的计算量与设计变量数目无关的效果。同时针对离散型伴随方法具体推导过程冗长易错的问题,选择性地利用自动微分技术对空间离散过程的各部分进行处理,既避免了盲目使用自动微分导致计算效率低下的问题,又大幅减小了离散型伴随方法具体形式的推导实现难度。翼型反设计问题和约束优化问题计算结果展示了本文方法的有效性。

基于CG法及Taguchi理论的气动力鲁棒性优化方法

针对传统的基于固定设计点气动力优化设计方法中存在的非设计点性能较差的问题,利用Taguchi鲁棒性设计理论和共轭梯度(Conjugate Gradient,CG)法,在斯坦福大学的开源CFD软件平台SU2的基础上,提出了一种高鲁棒性气动力优化设计方法。以NACA0012翼型为算例,以降低波阻为目标,对翼型的气动外形进行了鲁棒性优化设计,并与单点设计结果进行了对比。研究结果表明,采用提出的高鲁棒性气动力优化设计方法,在一定的亚声速范围内可以有效降低翼型波阻,实现翼型在波动飞行环境下的高鲁棒性气动力设计。研究结果对高鲁棒性气动力优化设计具有一定的工程指导价值。

PARETO FRONT CAPTURE USING DETERMINISTIC OPTIMIZATION METHODS IN MULTI-CRITERION AERODYNAMIC DESIGN

Deterministic optimization methods are combined with the Pareto front concept to solve multi-criterion design problems. The algorithm and the numerical implementation are applied to aerodynamic designs. Evolutionary algorithms （EAs） and the Pareto front concept are used to solve practical design problems in industry for its robustness in capturing convex, concave, discrete or discontinuous Pareto fronts of multi-objective optimization problems. However, the process is time-consuming. Therefore, deterministic optimization methods are introduced to capture the Pareto front, and the types of the captured Pareto front are explained. Numerical experiments show that the deterministic optimization method is a good alternative to EAs for capturing any convex and some concave Pareto fronts in multi-criterion aerodynamic optimization problems due to its efficiency.

Pneumatic resistance network analysis and dimension optimization of high pressure electronic pneumatic pressure reducing valve

The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.

Design and parametric optimization of thermal management of lithium-ion battery module with reciprocating air-flow

Single cell temperature difference of lithium-ion battery(LIB) module will significantly affect the safety and cycle life of the battery. The reciprocating air-flow module created by a periodic reversal of the air flow was investigated in an effort to mitigate the inherent temperature gradient problem of the conventional battery system with a unidirectional coolant flow with computational fluid dynamics(CFD). Orthogonal experiment and optimization design method based on computational fluid dynamics virtual experiments were developed. A set of optimized design factors for the cooling of reciprocating air flow of LIB thermal management was determined. The simulation experiments show that the reciprocating flow can achieve good heat dissipation, reduce the temperature difference, improve the temperature homogeneity and effectively lower the maximal temperature of the modular battery. The reciprocating flow improves the safety, long-term performance and life span of LIB.

Aerodynamic Optimum Design of Transonic Turbine Cascades Using Genetic Algorithms

This paper presents an aerodynamic optimum design method for transonic turbine cascades based on the Genetic Algorithms coupled to the inviscid flow Euler solver and the boundary-layer calculation.The Genetic Algorithms control the evolution of a population of cascades towards an optimum design.The fitness value of each string is evaluated using the flow solver. The design procedur6 has been developed and the behavior of the genetic algorithms has been tested. The objective functions of the design examples are the minimum mean-square deviation between the aimed pressure and computed pressure and the minimum amount of user expertise.

Study on Aerodynamic Design Optimization of Turbomachinery Blades

This paper describes the study on aerodynamics design optimization of turbomachinery blading developed by the authors at the Institute of Engineering Thermophysics, Chinese Academy of Sciences, during the recent few years. The present paper describes the aspects mainly on how to use a rapid approach of profiling a 3D blading and of grid generation for computation, a fast and accurate viscous computation method and an appropriate optimization methodology_ including a blade parameterization algorithm to optimize tm-bomachinery blading aerodynamically. Any blade configuration can be expressed by three curves, they are the camber lines, the thickness distributions and the radial stacking line, and then the blade geometry can be easily parameterized by a number of parameters with three polynomials. A gradient-based parameterization analytical method and a response surface method were applied herein for blade optimization. It was found that the optimization process provides reliable design for turbomachinery with reasonable computing time.

Blade Parameterization and Aerodynamic Design Optimization for a 3D Transonic Compressor Rotor

The present paper describes an optimization methodology for aerodynamic design of turbomachinery combined with a rapid 3D blade and grid generator （RAPID3DGRID）, a N.S. solver, a blade parameterization method （BPM）, a gradient-based parameterization-analyzing method （GPAM）, a response surface method （RSM） with zooming algorithm and a simple gradient method. By the use of blade parameterization method a transonic com- pressor rotor can be expressed by a set of polynomials, and then it enables us to transform coordinate-expressed blade data to parameter-expressed and then to reduce the number of parameters. With changing any one of the parameters and by applying grid generator and N.S. solver, we can obtain several groups of samples. Here only ten parameters were considered to search an optimized compressor rotor. As a result of optimization, the adiabatic efficiency was increased by 1.73%.

Aerodynamic design optimization by using a continuous adjoint method

This paper presents the fundamentals of a continuous adjoint method and the applications of this method to the aerodynamic design optimization of both external and internal flows.General formulation of the continuous adjoint equations and the corresponding boundary conditions are derived.With the adjoint method,the complete gradient information needed in the design optimization can be obtained by solving the governing flow equations and the corresponding adjoint equations only once for each cost function,regardless of the number of design parameters.An inverse design of airfoil is firstly performed to study the accuracy of the adjoint gradient and the effectiveness of the adjoint method as an inverse design method.Then the method is used to perform a series of single and multiple point design optimization problems involving the drag reduction of airfoil,wing,and wing-body configuration,and the aerodynamic performance improvement of turbine and compressor blade rows.The results demonstrate that the continuous adjoint method can efficiently and significantly improve the aerodynamic performance of the design in a shape optimization problem.

A Study of 3D Aerodynamic Design for a Transonic Compressor Blading Optimized by the Locations of Aerofoil Maximum Thickness and Maximum Camber

A design procedure for improving the efficiency of a transonic compressor blading was proposed based on a rapid generation method for three-dimensional blade configuration and computational meshes, a three-dimensional Navier-Stokes solver and an optimization approach. The objective of the present paper is to design a transonic compressor blading optimized only by selection of the locations of maximum camber and maximum thickness for the airfoils at different span heights and to study how do these two design parameters affect the blade performance. The blading configuration and the computational meshes can be obtained very rapidly for any given combination of maximum camber and maximum thickness. The computational grid system generated is used for the Navier-Stokes solution to predict adiabatic efficiency, total pressure ratio and flow rate. As a main result of the optimization, adiabatic efficiency was successfully improved.

Exploration in Optimal Design of an Airfoil with a Leading Edge Rotating Cylinder

Based on the theory of moving surface boundary layer control(MSBC),a concept of an airfoil having a rotating cylinder at the leading edge has been developed and experimentally proven to have good aerodynamic performance even at large angles of attack.Thus,this research aims to give guidance on optimizing the design of this kind of airfoil with high lift coefficients.Using computational fluid dynamics(CFD)technique,the CFD simulation results have been compared with the experimental results available in the literature,and then the SST two-equation model is selected as the appropriate turbulence model.At a given cylinder surface velocity ratio,the cylinder diameter d,the drop height of trailing edgeδand the curvatures of the pressure and suction surfaces of the airfoil are regarded as the optimal design parameters and the airfoil lift coefficient is considered as the optimization objective function.Therefore,using orthogonal optimization method,we herein develop a new design of airfoil favorable for having a rotating leading edge.It has been numerically proven that the resulting airfoil has good capability of achieving a substantially superior performance when compared to the airfoils of the prior art.

Multi-objective optimization of shock control bump on a supercritical wing

Based on the supercritical ＂wingl＂ which was released in the DPW-III conference, multi-objective optimization has been done to increase the lift-drag ratio at cruise condition and improve transonic buffet boundary and drag-rise performance. Hicks-Henne shape functions are used to represent the bump shape. In the design optimization to increase lift-drag ratio, the objectives involve the cruise point and three other off-design points nearby. In the other optimization process to improve buffet and drag-rise performance, three buffet onset points near the cruise point and one drag-rise point are selected as the design points. Non-dominating sort genetic algorithm II （NSGA-II） is used in both processes. Additionally, individual analysis for every selected point on the Pareto frontier is conducted in order to avoid local convergence and achieve global optimum. Re- sults of optimization for aerodynamic efficiency show a decrease of 11 counts in drag at the cruise point. Drag at nearby off-design points are also reduced to some extent. Similar approaches are made to improve buffet and drag-rise characteristics, resulting in significant improvements in both ways.