عنوان مقاله [English]
In helicopter design, determining the geometric shape of the fuselage is one of the main and primary issues that affect the performance characteristics of the helicopter. The aerodynamic coefficients of the helicopter fuselage are the main criteria for determining the quality and appropriateness of the geometric shape of the helicopter fuselage. Optimal design of helicopter body geometry is a complex activity and it is necessary to determine the effects of different parameters of helicopter geometry on aerodynamic coefficients. In this paper, design of computer experiments based on simulation of computational fluid dynamics to study the effects of the main parameters of the helicopter body geometry, such as ratio of largest helicopter body width to helicopter length, ratio of largest helicopter body height to helicopter length and nose to radius of curvature radius ratio The fuselage is based on the aerodynamic coefficients of drag, lift and torsional torque. The experiments are based on Taguchi's orthogonal array L25 (53). To determine the relationship between aerodynamic coefficients and parameters of the geometric shape of the helicopter fuselage and the importance of each parameter in aerodynamic coefficients, three-dimensional procedure diagrams, signal to noise ratios, mean of main effects, response procedure methodology and analysis of variance were used. Also, mathematical models were developed to estimate the aerodynamic coefficients of drag, lift and torsional torque through the response procedure methodology. The results at 95% confidence level show that the most effective parameter in the value of the helicopter body drag coefficient is the ratio of the largest height of the helicopter body to the length of the helicopter and in the lift and torsional torque parameters is the ratio of the largest width of the helicopter to the length of the helicopter.