Discussion on data and steady state

DR MASSEY (Paper 38): Tests have been made on models of in-line banks with variable transverse pitches and staggered banks with varying bypass

gaps. In both cases the wider gaps tended to pass more flow than would have been expected on

an area basis. This was of course due to the

lower frictional losses in these wider gaps.

An effect of this low friction was to draw air from the neighbouring channels of the bank and thus set up a cross-flow. This caused a drift of the incident temperature spike towards the wide pitches or bypass respectively.

Velocity measurements using laser doppler anemometry have confirmed these findings. In deed a simple model of the flow in an in-line bank, based on the measured velocity distrib ution, has predicted the drift of the temper ature spike quite accurately.