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An empirically-based prediction method for car aerodynamic lift and side forces
Technical Paper
1994-11-0100
Sector:
Event:
Vehicle Aerodynamics
Language:
English
Abstract
Following a similar approach to that used in the earlier MIRA
Drag Prediction Method, an empirically-based method has been
devised for estimating, from dimensional parameters, aerodynamic
lift and side forces experienced by cars and light vans.
In order to identify, and then quantify, the parameters with
significant influence on lift and side forces, MIRA's existing
data-base was extended to include data from the relevant
literature, together with new data from a substantial program of
wind-tunnel measurements carried out specifically for this
project.
The data-base consists mainly of wind-tunnel measurements on
variable- geometry models. From these, empirical relationships have
been derived to allow front, rear and total lift coefficients (at
zero yaw angle) and side force and yawing moment coefficients to be
predicted from the selected vehicle dimensional parameters. The
development of these relationships is detailed in this paper. A
computer program has been written into which these empirical
relationships have been incorporated.
Validation of the resulting prediction method against
wind-tunnel data for a wide range of vehicles has shown a fairly
good correlation between predicted and measured force and moment
coefficients. The need for further refinement of the method is
recognized, however, in order to realize its full potential as a
design tool