Study of cooling air inlet and exit geometries for horizontally opposed piston aircraft engines

Effect of Propeller on Engine Cooling System Drag and Performance

“…The results of Ref. 5 show that this particular side exit configuration increased flow separation over the rear part of the nacelle and thereby increased the drag. In the presence of the propeller slipstream, however, the drag is not only lower (generally), but also continues to decrease with flow rate; this is in contrast with the propeller-off configuration, for which the drag slightly increased with flow rates.…”

“…5. The upper plenum pressure recovery C p as a function of inlet area ratio A ^ IA f , where A " is the incoming flow cross-section area ahead of the model (Fig.…”