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The Bloodhound Project Oil Streak visualisation of airflows around the front end of BLOODHOUND SSC

Oil Streak visualisation of airflows around the front end of BLOODHOUND SSC

Engineering News
Friday, 8 May, 2009

Looking at some of the additional Aero work that is being done on the intake. This particular method of visualizing computer simulated flows uses what are called ‘surface constrained streamlines’.  These show the direction flow is taking adjacent to the surface of the vehicle and are the computational equivalent of the patterns that would be produced had the car been tested in a wind-tunnel and colored oil applied to the body ahead of test. In the pictures these streamlines are shown overlaid onto contours of the static pressure acting on the car which helps the aerodynamicist understand why the streak lines are behaving in the way they are.

Mach = 0.1 Surface Pressures and Streak lines


As the speed increases the flow pattern changes, the smoother these lines the better the car will travel through the air. Regions of abrupt direction change and areas of recirculation which indicate flow separation are designed out at every stage, and this is why when there is a change to the body surface, an analysis such as this is carried out. In the picture below you can see an example of recirculation on the canopy immediately ahead of the intake. This confirms that some further changes are required to the detail of the boundary layer diverter which is essentially a slot that prevents the boundary layer developed on the forebody of the car from being ingested by the jet.

Mach = 0.3 Surface Pressures and Streak lines


As the speed continues to increase the pressure gradients on the body further intensify. Shock waves are formed ahead of the nose of the car and in front of the intake. The red colour indicates regions of high (stagnation) pressure downstream of these shocks where the car is in effect pushing the air ahead of itself rather than cutting through it.

Mach = 1.3 Surface Pressures and Streak lines