Heat transfer rate and surface pressure measurements in short duration hypersonic flow

ABSTRACTExperiments were carried out with air as the test gas to obtain the surface convective heating rate and surface pressure distribution on blunt and sharp cone models flying at hypersonic speeds. Tests were performed in a hypersonic shock tunnel at two different angles of attack: ${0}^\circ$ and ${5}^\circ$ with angles of rotation $\phi = {0}^\circ, {90}^\circ$, and ${180}^\circ$. The experiments were conducted at a stagnation enthalpy of 1.4MJ/kg, flow Mach number of 6.56 and free stream Reynolds number based on the model length of $9.1 \times {10}^{5}$. The effective test time of the shock tunnel is 3ms. The results obtained for cone model with a bluntness ratio of 0.2 were compared with sharp cone models for $\alpha ={0}^\circ$. The measured stagnation heat transfer value matched well with the theoretical value predicted by the Fay and Riddell correlation and with the CFD results.

Modeling the processes of aerogasdynamics of structural elements of a supersonic aircraft

The purpose of the research was to study the aerodynamic features of the flow around the simplest structural elements of an aircraft, such as sharp and blunt-nose cones. For calculations we applied the perfect gas model. To describe flows with large adverse pressure gradients, we used the Menter's shear stress transfer model. We analyzed changes in the aerodynamic characteristics of the cones in a wide range of angles of attack α and flow Mach M∞ numbers. Furthermore, we investigated the parameters of the base region of the sharp cone at transonic and supersonic speeds, and compared the simulation results with the data of a physical experiment both in wind tunnels and on a ballistic installation. The comparison showed good agreement with the experimental data. Numerical simulation data can be applied to form the external appearance of aircraft for various purposes, to study the influence of the temperature factor on the flow around bodies, and to create semi-empirical models for calculating the parameters of the base region of conical bodies.

Hypersonic flow over spherically blunted cone capsules for atmospheric entry. Part 1. The sharp cone and the sphere

Depending on the cone half-angle and the inverse normal-shock density ratio $\unicode[STIX]{x1D700}$, hypersonic flow over a spherically blunted cone exhibits two regimes separated by an almost discontinuous jump of the body end of the sonic line from a point on the spherical nose to the shoulder of the cone, here called sphere behaviour and cone behaviour. The inflection point of the shock wave in sphere behaviour is explained. In Part 1 we explore the two elements of the capsule shape, the sphere and the sharp cone with detached shock, theoretically and computationally, in order to put the treatment of the full capsule shape on a sound basis. Starting from the analytical expression for the shock detachment angle of a cone given by Hayes & Probstein (Hypersonic Flow Theory, 1959, Academic Press) we make a hypothesis for the sharp cone, about the functional form of the dependence of dimensionless quantities on $\unicode[STIX]{x1D700}$ and a cone angle parameter, $\unicode[STIX]{x1D702}$. In the critical part of atmospheric entry the shock shape and drag of the capsule are insensitive to viscous effects, so that much can be learned from inviscid studies. Accordingly, the hypothesis is tested by making a large number of Euler computations to cover the parameter space: Mach number, specific heat ratio and cone angle. The results confirm the hypothesis in the case of the dimensionless shock stand-off distance as well as for the drag coefficient, yielding accurate analytical functions for both. This reduces the number of independent parameters of the problem from three to two. A functional form of the shock stand-off distance is found for the transition from the $90^{\circ }$ cone to the sphere. Although the analysis assumes a calorically perfect gas, the results may be carried over to the high-enthalpy real-gas situation if the normal-shock density ratio is replaced by the density ratio based on the average density along the stagnation streamline (see e.g. Stulov, Izv. AN SSSR Mech. Zhidk. Gaza, vol. 4, 1969, pp. 142–146; Hornung, J. Fluid Mech., vol. 53, 1972, pp. 149–176; Wen & Hornung, J. Fluid Mech., vol. 299, 1995, pp. 389–405).