Low Speed Small UAVs Aerodynamic Characteristics And RCS Computing Analysis

Recently, small Unmanned Aerial Vehicles (UAV) has been attracting the attention in world wide. Especially the airfoil profile design of low speed and the accuracy of calculating in the Radar Cross Section (RCS) have becoming the key parts in the small UVA development.First of all, this paper studies the single-point and multi-point aerodynamic shape optimization for airfoils, an optimized airfoil reduce the power consumption in air vehicles,while highly improving the aerodynamic efficiency and stability. The paper uses modified Hicks-Henne shape function method as the parametric description of airfoils, and Genetic Algorithm to complete the optimization. To get the better shape of the airfoil SD7062, the research respectively uses changing the parametric description method, increasing the number of design variables, and converting the table choice of Uniform Experimental method. The single-point optimization of the airfoil with the goal of maximizing its lift to drag ratio is firstly accomplished,and take the weight resistance coefficient as the goal of multi-point optimization.The research conclusions show that, modified Hicks-Henne shape function method is more appropriate for the airfoil optimization than the unmodified Hicks-Henne shape function method, and the description distortion about the whole airfoil and inaccuracy near the trailing edge which often occur when using the traditional method were all eliminated. After the optimization. Also, increasing the number of design variables can improve the aerodynamic efficiency at the design point, but if the optimization pay too much attention at the one design point,and ignore the other points’ influence,may have a negative effect on the shape of airfoil.At last, converting the table choice of Uniform Experimental method from to a new one has impact the optimization results, the new table has gain much more information in the limited experiment. The multi-point optimization is overall consideration of all the chosen design points, although it sacrifice the part of design points’ aerodynamic efficiency, it consists with the engineering application.The second part of the paper takes the calculation and research in the RCS, the accuracy and efficient calculation is the important precondition of the air vehicles’ stealth performance.Based on the FDTD, MoM and PO+IMEC method, respectively of cube and cylinder, date type structure and the triangle surface structure model to calculate. The calculation draw the conclusion: The MoM is suitable for high calculation precision, but time consuming is longest,the FDTD has high calculate precision, but it still using too much time, and prone to error in strong echo in reflection. The PO+IMEC takes shortest time, but the calculate precision is low.Finally the paper choose the MoM method to calculate the RCS of the small UVA, separately calculate the partial and the whole machine model of UVA, the part of the UAV is obtained mainly produce scattering source is the wing leading edge, main wing, tail, and analysis of the scattering form results.