Convective Heat Transfer for Pulsating Flow in the Takedown Pipe of a V-6 Engine

To examine the effects of pulsating flow, heat transfer parameters were measured on a heated takedown pipe for a recent commercial V-6 engine. Operation of the engine as an air compressor provided flow at rates from 250 to 750 slpm and engine speeds from 750 to 3250 rpm. Non-dimensional frequencies fell in the range 0.045 < w+ < 0.97, corresponding to high-frequency flows rather than quasi-steady. Compared to a modified Dittus-Boelter correlation, halfway along the test section the convective heat transfer parameters for pulsating flow showed convective enhancement factors of the order of three to eight for engine speeds to 1750 rpm; for steady flow from a comparable manifold these factors were approximately two.