Mitsunori Watanabe

Orbital re-entry experiment vehicle ground and flight dynamic test results comparison

The angular motion of an orbital re-entry experiment (OREX) vehicle model was tested in a transonic wind tunnel using a single-degree-of-freedom test method to investigate the angular motion of the OREX vehicle. The purpose of the OREX is to test heat shield materials and to obtain measurements of an aerodynamically heated flowfield. Approximate static and dynamic derivatives of the model were measured by a local linear curvefitting method. The angular motion of real OREX flight data was compared with the wind-tunnel test results. The maximum amplitude of the OREX vehicle in the transonic region is almost the same as that obtained in the wind-tunnel test.

Prediction of Supersonic Aerodynamics for a Mars Entry Capsule Using Large Eddy Simulation

A numerical investigation of supersonic flow around a sphere-cone shapes capsule is performed using Large Eddy Simulation (LES). The unsteady CFD simulation using an implicit LES approach is conducted for the corresponding experimental measurement of aerodynamic forces performed in a supersonic wind tunnel facility. The obtained static aerodynamic coefficients by LES are compared with the experimental data and their accuracies are evaluated for Mach numbers from 1.4 to 4.0 and angles of attack from 0° to 15°. The effects of grid resolution and spatial accuracy on aerodynamic forces are also investigated.

FLAT SPIN OF RECTANGULAR CYLINDERS IN LOW SPEED FLOW

To investigate the flat spin of rectangular cylinders, steady flat spin rates with respect to free stream Reynolds numbers were measured by using 90-deg-edged and SR-round-edged rectangular models at an angle of attack of 90 deg. The steady reduced flat spin rates are almost independent of the Reynolds numbers for 90-deg-edged models. The steady reduced flat spin rates for rounded rectangular cylinders, however, are influenced by the Reynolds numbers in the region Re, < 4~10~. The transient yawing moment acting on the 90-degedged models shows a two-step acceleration, i.e., small moment acts in the initial slow spin stage, then on the halfway to the steady (final) spin rate, a large moment begins to act. On the rounded rectangular models, on the other hand, a large moment begins to act just after slow spin starts. The steady reduced spin rate is estimated by locally integrating the static forces acting on a two-dimensional squared cylinder at angles of attack.