Streamlined bodies drag force estimation using wake integration technique

Abstract

In this paper, the drag force calculation around the SUBOFF submarine in axisymmetric configuration was investigated using the "Wake Integration Technique." This method is usually used in wind tunnels as an auxiliary method instead of the common "surface integral technique" for flow around complex geometries or shock wave flows. The results of this method are dependent on data collection vertex space, distance, and section size, where practical suggestions were made for each parameter in this research. Furthermore, the contribution of the pressure, momentum, and fluctuation terms in the total drag force were also evaluated at different cross sections. These findings can be implemented in wind tunnels with small test section length and also to compare the results obtained by the common surface integral method. Simulations were carried out at different aspect ratios at zero angles of attack, and the capabilities of this method at inclined flows were also discussed. The obtained results were also compared against the common method, and the results show only 4% deviation at zero angle. Keywords Wake survey • Wind tunnel • Drag force • Momentum defect principle • Suboff submarine List of symbols L Body length D Maximum body diameter AR Length-to-the-diameter aspect ratio x, y, z Coordinate system Δx, Δy Grid space in x and y-direction d The ratio of grid space to diameter X Longitudinal distance from the body r Measurement radius S Surface area P , u Local pressure and velocity P ∞ , U ∞ Free-stream pressure and velocity C D Drag coefficient C p Pressure coefficient Incidence angle y + Dimensionless wall distance Fluid density xx Normal stress component

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