No description available.

No description available.

No description available.

The main aim of this study was to investigate noise reduction techniques for bluff body noise. Three methods were investigated, using a splitter plate on a fairing- strut configuration, applying flow control to the surface of a fairing and fitting a splitter plate behind a isolated bluff body. Aerodynamic tests were performed in wind tunnel facilities using particle image velocimetry (PIV), hotwire anemometry, pressure sensors and a force balance. Acoustic tests using a microphone array, on-surface microphones and freefield mi- crophones were performed to investigate the noise generated by the models. The splitter plate fitted to the fairing-strut configuration was found to be dominated by large scale vortex shedding. The addition of the splitter plate blocked the interaction between the two opposing shear layers aft of the shell's trailing edge thereby reducing their interaction with the downstream strut. Broadband noise reductions were observed as well as reduction in the noise levels of the peaks asso- ciated with the shedding. Applying flow control showed noise reductions for both cases when suction and blowing were applied. These reductions were observed at the lower tested Reynolds numbers (ReDshell = 1.75 x 105), at higher Reynolds numbers (ReDshell = 3.5 x 105) the noise reductions decreased when compared to the baseline case. The splitter plate fitted behind an isolated bluff body modified the wake, decreasing shedding frequency and drag with an increase in the splitter plate length. Broadband noise reductions were observed with all three splitter plate lengths and the tonal peak of the vortex shedding noise was suppressed. The study shed light on the possibility of achieving noise reductions using the three methods. However more research is required to apply these findings on a landing gear.

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This study investigates the aerodynamics of nil inverted wing in ground effect, a race car wheel and the interaction between the two components, using numerical and experimental methods. The wheels were located behind the wing at flU overlap and gap of 20mm, and the wing ride height. iu the vertical direction was the primary variable. Models of 50% scale were used , giving a Reynolds number of 5.8 x 105 based on the wing chord . The Detached-Eddy Simulation model was validated against wind tunnel measurements including PIV, surface pressures and forces , where it was found to outperform a Reynolds averaged Navier-Stokes approach which used the Spalart-Allmaras turbulence model. It accurately predicted the wing vortex breakdown at low ride heights, which is of the bubble type with a spiralling tail, and the wake of the wheel. A mesh sensitivity study revealed that a finer mesh increased the amount of structures captured with the DES model, improving its accuracy.

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No description available.

No description available.

The work reported in this text describes the development of an advanced method for the aerodynamic testing of model propellers. The technique involves the measurement of the time averaged surface pressure distributions on rotating model propeller blades, thereby giving access to more detailed information than was previously possible. This information may be used both to improve the fundamental understanding of propeller aerodynamics, and to provide high quality detailed validation data for theoretical predictive techniques. The experimental system is described, and results showing the effects of changes in advance ratio, blade setting angle, number of blades and nacelle geometry are discussed. Flow phenomena unrepresentative of full scale flight conditions were identified and removed, thus ensuring the realistic testing of propellers at model scale. In addition, the development of a potential flow theoretical method for the prediction of the flowfield around propeller/axisymmetric nacelle combinations is described. The technique uses a vortex lattice representation for the propeller blades, together with a surface source distribution for the non-lifting surfaces (spinner, hub and nacelle). The method is found to predict all the trends experimentally observed and to give good numerical agreement for the blade surface pressures over the outboard half of the propeller radius