Browsing by Author "Chaplin, Ross"
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Item Open Access Aerodynamic interference between high-speed slender bodies(Cranfield University, 2009-12) Chaplin, Ross; MacManus, David G.Significant aerodynamic interference can occur between high-speed bodies in close proximity. A complex flowfield develops where shock and expansion waves from a generator body impinge upon the adjacent receiver body. The pressure and flow angularity changes which occur across these disturbances modify the body aerodynamics. The aim of this research is to quantify the aerodynamic interference effects for multi-body configurations and understand the relevant flow physics. The interference aerodynamics for slender bodies in a supersonic flow were investigated through a parametric wind tunnel study. The receiver bodies were finned and un-finned configurations. The effect of lateral and axial body separations, receiver incidence and the strength of the disturbance field were investigated. Measurements included forces and moments, surface pressures and flow visualisations. Supporting computations using steady-state, viscous predictions provided a deeper understanding of the underlying aerodynamics and flow mechanisms. Good agreement was found between the measured and predicted interference loads and surface pressures for all configurations. The interference loads are strongly dependent upon the axial impingement location of the primary shockwave. These induced loads change polarity as the impingement location moves aft over the receiver. The magnitude of the interference loads increase when the receiver is at incidence and are amplified by up to a factor of three when rear fins are attached. In general, the interference loads are larger for a stronger disturbance flowfield. The centre of pressure location is substantially affected and the static stability of the finned receiver changes in some configurations. The effect of the aerodynamic interference on the body trajectories was assessed using an unsteady, Euler prediction in combination with a 6DOF dynamic model. This shows aerodynamic ii interference can cause a collision between the bodies. Moreover, the initial interference loads dominate the subsequent body trajectories and static modelling can be used to evaluate the dynamic trajectories.Item Open Access Aerodynamic Interference on Finned Slender Body(American Institute of Aeronautics and Astronautics, 2016-04-28) Chaplin, Ross; MacManus, David G.; Leopold, Friedrich; Martinez, Bastien; Gauthier, Thibaut; Birch, TrevorAerodynamic interference can occur between high-speed slender bodies when in close proximity. A complex flowfield develops where shock and expansion waves from a generator body impinge upon the adjacent receiver body and modify its aerodynamic characteristics in comparison to the isolated case. The aim of this research is to quantify and understand the multibody interference effects that arise between a finned slender body and a second disturbance generator body. A parametric wind tunnel study was performed in which the effects of the receiver incidence and axial stagger were considered. Computational fluid dynamic simulations showed good agreement with the measurements, and these were used in the interpretation of the experimental results. The overall interference loads for a given multibody configuration were found to be a complex function of the pressure footprints from the compression and expansion waves emanating from the generator body as well as the flow pitch induced by the generator shockwave. These induced interference loads change sign as the shock impingement location moves aft over the receiver and in some cases cause the receiver body to become statically unstable. Overall, the observed interference effects can modify the subsequent body trajectories and may increase the likelihood of a collision.Item Open Access A case study on the aerodynamic heating of a hypersonic vehicle(Royal Aeronautical Society, 2012-09-30T00:00:00Z) Mifsud, Michael; Estruch-Samper, David; MacManus, David G.; Chaplin, Ross; Stollery, J. L.A Parabolised Navier-Stokes (PNS) flow solver is used to predict the aerodynamic heating on the surface of a hypersonic vehicle. This case study highlights some of the main heat flux sensitivies to various conditions for a full-scale vehicle and illustrates the use of different complimentary methods in assessing the heat load for a realistic application. Different flight phases of the vehicle are considered, with freestream conditions from Mach 4 to Mach 8 across a range of altitudes. Both laminar and turbulent flows are studied, together with the effect of the isothermal wall temperature, boundary-layer transition location and body incidence. The effect of the Spalart-Allmaras and Baldwin-Lomax turbulent models on the heat transfer distributions is assessed. A rigorous assessment of the computations is conducted through both iterative and grid convergence studies and a supporting experimental investigation is performed on a 1/20th scale model of the vehicle's forebody for the validation of the numerical results. Good agreement is found between the PNS predictions, measurements and empirical methods for the vehicle forebody. The present PNS approach is shown to provide useful predictions of the heat transfer over the axisymmetric vehicle body. A highly complex flow field is predicted in the fin-body-fin region at the rear of the vehicle characterised by strong interference effects which limit the predictions over this region to a predominately qualitative level.