Optimisation of a Transonic Flow Radial Vaned Diffuser,
ALFA ROMEO AVIO S P A NAPLES (ITALY)
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The transonic flow in an existing radial vaned diffuser has been analysed with a time dependent finite area calculation method. The calculated Mach number distribution indicates a strong bow shock upstream of the throat. Based on this experience, new diffusers have been designed in order to optimize the Mach number distribution in the semi-vaneless space by designing for a shock free deceleration. The best predictions are obtained with a modified version of the design method of Herbert and Came in which a radial change of diffuser width is incorporated. Experimental results obtained with this optimised design show an important increase in range and confirm the shock-free deceleration of the flow. The difference between the calculated and measured pressure distribution can be explained by incidence effects due to an incorrect estimation of the boundary layer the real flow conditions at the diffuser inlet becomes available.
- Fluid Mechanics
- Hydraulic and Pneumatic Equipment