Aircraft engines need a cooling system to keep the engine oil well within the temperature limits for continuous operation. The aircraft selected for this study is a typical pusher type Light Transport Aircraft (LTA) having twin turbo prop engines mounted at the aft end of the fuselage. Due to the pusher propeller configuration, effective oil cooling is a critical issue, especially during lowspeed ground operations like engine idling and also in taxiing and initial climb. However, the possibility of utilizing the inflow induced by the propeller for oil cooling is the subject matter of investigation in this work. The oil cooler duct was designed to accommodate the required mass flow, estimated using the oil cooler performance graph. A series of experiments were carried out with and without oil cooler duct attached to the nacelle, in order to investigate the mass flow induced by the propeller and its adequacy to cool the engine oil. Experimental results show that the oil cooler positioned at roughly 25 % of the propeller radius from the nacelle center line leads to adequate cooling, without incorporating additional means. Furthermore, it is suggested to install a NACA scoop to minimize spillage drag by increasing pressure recovery.
Experimental and numerical investigation of fore body geometrical effects on drag and flow-field of non-circular cylinder (D-shaped bluff body) were conducted in the subcritical flow regime at Reynolds number in the range of 1 x 10 5 ≤ Re ≤ 1.8 x 10 5. To shield the non circular cylinder (D-shaped model) front surface from the positive pressure of the unsteady vortex generation in the near wake, circular disk of various geometries were attached upstream of the non-circular cylinder base model. The fore body makes the streamlines that separate from its edges to attach smoothly onto the front face shoulders of the main body, thereby converting the bluff body into an equivalent streamlined body to result in low drag. The diameter of the fore body (b1) ranges from 0.25 to 0.75 times the hydraulic diameter of base model (b2) and the gap ratio (g/ b2),was in the range from 0.25 to 1.75 b2. The experimental and numerical investigations show that by using a circular disk as fore body with a width ratio b1/b2 of 0.75 and a gap ratio of g/ b2 = 0.75 results in a configuration having percentage drag reduction of about 67 % and 65 % respectively.
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