Investigation of Engine Oil-cooling Problem during Idle Conditions on Pusher Type Turbo Prop Aircraft

Abstract

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.

Study on oil-cooler location for a pusher type turbo prop aircraft using numerical simulation

“…Upon validating the integrity of the numerical simulation (Premkumar et al , 2017), a five-bladed propeller with oil cooler installed in different radial locations in front of the propeller has been investigated further to ascertain the thrust loss. Numerous researches have been carried out in the area of propeller computation.…”

“…Additionally, with a view to capturing the boundary layer effects, the maximum boundary layer thickness has been calculated, and 12 prism layers of the grid have been created within the calculated boundary layer thickness around the blade region (Zhang et al , 2015) as shown in Figure 4. After pre-processing, the rotational domain values are validated against empirical data (Premkumar et al , 2017).…”

“…Several authors (Devine et al , 2004) developed exciting models having air scoops/NACA scoops to minimise pressure loss which has been tested and validated against experimental data. To simplify the oil cooler installation, many researchers including the author (Premkumar et al , 2017) investigated using propeller suction to induce flow through the oil cooler to vent the excess engine oil temperature caused due to the inadequacy of ram air during idle conditions. Currently, there is a limited research article available to analyse the thrust loss incurred by the pusher propeller flow due to the positional obstruction of the oil cooler duct.…”