Aerodynamics and Flow-Field Analysis

ACI has extensive experience in Low and High Speed Aerodynamics and in Flow-Field Analysis. This expertise includes both experimental techniques and Computational Fluid Dynamics (CFD) methods. The CFD methods used by ACI personnel range from simple Potential Flow, such as vortex lattice and panel codes, to full 3-D Navier-Stokes methods.

The pictures shown below represent work that used both aerodynamic analysis and CFD methods. These pictures represent shadowgraphs of a planetary atmospheric entry model that uses aerobraking technology. This model was tested in the ballistic range at NASA / Ames Research Center. The test section pressure was 15 mm Hg, the velocity was 4.1 km/sec. The picture on the left is the experimental shadowgraph; the picture on the right is the shadowgraph overlayed with computed pressure contours. The agreement of the shock locations indicate that the computed solution correctly models the air dissociation caused by the high speed of the model. For this test, the trajectory of the model was defined by a sequence of shadowgraph images. The aerodynamic forces were modeled using functions of the pitch, roll, and yaw angles and the angular rates. Undetermined parameters in these functions were found by using the aerodynamic forces to calculate the trajectory and by making small adjustments to the parameters until the calculated trajectory best approximated the experimental trajectory.