The hydrodynamics of bubble columns operated at pressures up to 7.0 MPa are investigated using a laser Doppler velocimetry system. Laser Doppler velocimetry is a noninvasive optical technique, which is used to conduct in situ measurements of velocity, with high spatial resolution, fast dynamic response, and the ability to detect flow. The axial and tangential velocities and the Reynolds shear and normal stresses are analyzed and discussed in relation to large-scale structures present in the flow. This study demonstrates the significance of the pressure effect on the flow field in bubble-column systems.

The flow past an unmanned combat air vehicle (UCAV) 1303 was investigated in a water tunnel in an effort to understand the complex flow field. The UCAV 1303 is characterised by a non slender, 47° swept-leading-edge delta wing, with a cranked trailing edge, a cropped wing tip and a fuselage. It also has no vertical tail. Dye visualisation pictures and five-axis strain gage load data were obtained on a 1:72 scale model in both steady flow and while the model executed preprogrammed manoeuvres. From the strain gage data, body axis force and moment data were derived. In addition to some similarities, comparison of the flow features observed with those of more well known slender delta wing flows showed some remarkable differences such as tip-stall, the presence of two like-sense vortices on the same side of the wing, their simultaneous spiral and bubble bursting. This paper predominantly discusses the flow visualisation results and attempts to correlate the load data to some of the observed flow features.