S. . Santhakumar

Abstract: A method is developed to obtain quick engineering estimates for the normal load on slender airbreathing shapes. Estimates of the normal load can be obtained using a Trefftz plane analysis. This computation, although two-dimensional and subsonic, agrees fairly well with experimental data (from NASA and AGARD) for three-dimensional slender bodies in supersonic flows. The computational technique is simple and extremely fast.

Abstract: A wind-tunnel test program was conducted to generate a systematic aerodynamic database for airbreathing vehicles. Generic models consisting of tangent ogival nose, cylindrical body with cruciform intakes or twin intakes were tested at freestream Mach numbers ranging from 0.5 to 3.0. The length and span of intakes were varied. The intakes were two-dimensional with blocked entry. Normal force and pitching moment were nondimensionalized using planform area and distance of centroid (from nose tip) of the planform of the model rather than body cross-sectional area and body diameter, which are traditionally used. When normal-force and pitching-moment coefficients nondimensionalized this way are plotted against angle of incidence, the coefficients of different configurations coalesce for zero roll. In addition, data for different roll angles are found to coalesce when an empirical function of roll angle is introduced in the nondimensionalizing. A prediction method was developed to estimate the normal force and pitching moment of similar body-intake configurations based on this trend. Nomenclature A = cross-sectional area A B = body cross-sectional area of the configuration, = πr 2 A P = planform area of configuration APB = planform area of body API = planform area of intakes alone, A P − APB A R = reference area (equal to A P unless otherwise specified) Cdn = crossflow drag coefficient of circular cylindrical section Cm = pitching-moment coefficient about nose, M p/ qA R X CmNL = nonlinear component of pitching-moment coefficient about nose C N = normal-force coefficient, = N/ qA R C N NL = nonlinear component of normal-force coefficient cn = local normal-force coefficient per unit length d = body diameter H = height of air intake l = length of model li = length of air intake M = freestream Mach number M p = pitching moment about nose N = normal force q = freestream dynamic pressure r = body radius s = total span of body-intake configuration W = width of air intake

Abstract: Aerodynamic study over body-intake configurations has been carried out using a CFD code, PARAS. Body -Twin Intake and Body-Cruciform Intake configurations were studied. The air- intakes are two-dimensional. Computations were carried out for Mach numbers 2.0 and 3.0, angle of incidence from -10 o to +10 o and roll angles 0 o and 45 o . Computations with and without flow through the intakes were carried out. The CFD results were compared with the experimental data and the agreement is found to be good. The effect of flow through intakes on normal force and pitching moment is not significant where the effect is significant on axial force. 6 and Vipin kumar 7 on body-intake configurations for measurement of external aerodynamic coefficients. The objective of present study is to find the applicability of the CFD code, PARAS-3D for the prediction of the external aerodynamics of body-intake configurations and also to find the effect of flow through intakes on external aerodynamic coefficients. The details of body-intake configurations, PARAS-3D code and the computational results are presented. Comparison of the CFD results with experimental data is also presented. II. Body-intake Configurations Two configurations were investigated. configuration-1 consists of body with two side-mounted intakes (twin intake configuration) and configuration-2 consists of body with four intakes (cruciform intake configuration). The body consists of ogival nose followed by circular cylinder. The body is identical for both configurations. Diameter of the body is 27 mm. Nose fineness ratio is 3 and slenderness ratio of the model is 15. The intakes are 2-dimensional. Length and span of intakes of both configurations is same. Thickness of intakes of twin intake configuration is twice that of intakes of cruciform configuration. For twin intake configuration, intake entry plane is not facing the body. For cruciform intake configuration, intake entry plane is facing the body. Angle of intake entry plane is 34.4° with respect to flow direction for all he intakes. The details of the configurations are shown in Fig.1. In the flow through condition, the thickness of the intake walls is taken as 0.5mm. III. PARAS-3D code PARAS-3D code is a PARallel Aerodynamic Simulator, which can simulate viscous, turbulent and three-dimensional fluid flow over arbitrary three-dimensional bodies. The grid around the bodies is generated by means of a Rectangular Adaptive Cartesian Mesh (RAM) technique. This code is based on explicit scheme with second order accurate in space and of total variation diminishing (TVD) type, which is $