Abstract:
Automotive components are tested extensively in wind tunnels by automotive manufacturers
and race teams. This is usually achieved using an accurate scale model
representation of the component within the wind tunnel.
Automotive heat exchangers, however, are comprised of numerous intricate geometries
and are therefore impractical to produce at model scale. Instead they are
simply modelled as pressure drops, achieved using a thin mesh or honeycomb of
known porosity. Most commercial computational fluid dynamics solvers ignore the
geometry of the heat exchanger and instead model it as a discontinuity with a known
pressure drop and heat transfer.
The pressure drop across an automotive heat exchanger, however, was found to
vary with both the coolant temperature and the angle of inclination of the heat
exchanger. This thesis initially presents a relationship between the pressure drop
coefficient and the inclination angle for varying media porosities. Mathematical
relationships for inclination angles of 0°, 15°, 30° and 45°. were derived relating
this pressure drop coefficient to the porosity of the media. Weighted least squares
is proposed over ordinary least squares when obtaining the Forchheimer equation
coefficients from experimental measurements.
Investigation extends into the thermo-fluid effects on a full scale automotive heat
exchanger when inclined at 0 °, 15°, 30° and 45°. It was found, depending on the
angle, that there was a difference in the pressure drop of up to 10% between the
unheated and heated (100 C) heat exchanger. Based on the proposed mathematical
relationship, this correlated to a 4% decrease in porosity in order to accurately model
the automotive heat exchanger at subscale.
The thesis concludes with experimental and numerical investigation into the heat
transfer on a hydrodynamically and thermally developing ow within a radiator
channel. Laser doppler anemometry measurements recorded a 1.5% increase in the
centreline velocity compared to 0.8% obtained from numerical simulation.
