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An experimental visualization study was performed to investigate the dependence of the pressure hill height and the influence zone expanse, for flow past a spiked body with different nose configurations, over a Reynolds number range from 2278 to 4405 to establish the vortex shedding process, and applicability in low speed flow regime for effective pressure reduction. It is found that the spike reduces the radius of curvature of the approaching streamline, leading to the deflection of the streamlines towards the shoulder of the basic body, resulting in a narrow zone of the positive pressure hill at the body nose. It is also observed that the pressure hill length and the influence zone expanse decrease with the introduction of spike over the present range of Reynolds numbers. For Reynolds numbers less than 2700, spike with conical nose is found to be more efficient than the spikes with other nose shapes of the present study in reducing the positive pressure at the nose of the blunt body. For higher Reynolds numbers, greater than 2700, the size of the vortex at the junction of the spike and basic body is the largest for the spike with hemispherical nose, and emerges as a potential candidate for application in possible wind-design resistant structures.

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An aerospike, in front of a blunt body, has largely been deemed as a key passive control device for effectively reducing the wave drag and aerodynamic heating associated with high-speed flows. In addition, it has been reported that the presence of a spike brings in unsteadiness in the form of oscillation and pulsation to the flow characteristics. Past researchers, having investigated mainly the aerothermodynamic coefficients, have hinted towards the suppressing of such oscillations with the use of a round nose spike over a sharp spike, though a thorough and a concrete result is yet to be established together with offering a detailed explanation of the flow physics and its dependence on the spike’s geometric characteristics (spike-length to afterbody-diameter ratio, L/D). Numerical investigation has been carried out using axisymmetric Navier-Stokes laminar flow solver at hypersonic Mach number of 6.0. A round-tip spike with a flat face cylindrical afterbody have been simulated for spike length ratios of L/D = 0.5 – 2.0, with spike diameter to-afterbody diameter (d/D) of 0.1. The behavior and subsequent control of flow pulsation for a round (hemispherical) spike with varying L/D-ratio has been established.