While the ideal from an aerodynamic stand would be non-intrusive, until an economical technique is developed there will be occasions when the user will be prepared to resort to an intrusive method. Preliminary experiments on surface flow visualization in the cryogenic wind tunnel by use of condensing or freezing gasesĬryogenic wind tunnel users must have available surface flow visualization techniques to satisfy a variety of needs. This visualization clearly shows the flow reattachment on the back surface of a capsule, which is suspected to induce the rapid rolling motion. In order to investigate the flow field around the capsule, the combined technique of color schlieren and surface tufts is applied. Moreover, it rolls multiple times during the test. Similarly, the HTV-R model exhibits pitch and yaw oscillations in a flow of Mach 0.5. In a flow of Mach 0.9, the SPH model exhibits oscillations in pitch and yaw, and it rolls half a turn during the test. The developed mounting apparatus is used in the wind tunnel tests with these capsule models. Two types of capsule models are prepared, one is drag type (SPH model) and the other is lift type (HTV-R model). This 3-DOF free rotational mounting apparatus achieves the least frictional torque from the support and the instruments. A special support is developed to allow the model to rotate around the pitch, yaw and roll axes.

The rotational behavior of capsule-shaped models is investigated in the transonic wind tunnel of JAXA. With its very extensive Reynold's number domain (10 to the 4th - 10 to the 6th), this tunnel has shown itself to be well adapted to the study of turbulence and of the flow instabilities related to its appearance.įlow visualization around a rotating body in a wind tunnel

The experimental technique used for visualizing laminar-turbulent transition phenomena, developed in previous tests in ONERA's small TH1 water tunnel, has been successfully applied in the new TH2 tunnel. Flow instability and turbulence - ONERA water tunnel visualizations

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