CFD Based Investigation on Effects of Compression Surface At Fighter Aircraft Engine Intake

摘要

The purpose of the intake of an aircraft is to supply the engine with a proper airflow during various flight conditions. A good intake design is characterized by providing high pressure recovery and low distortion. Therefore it is essential to divert as much of the boundary layer as possible since it is a factor which affect the quality of the airflow. On aircrafts with engines installed on wing pylons, which is the most common configuration on transport and passenger aircraft, the inlet is short and leads directly to the engine and the pressure recovery is good. For engines that are integrated with the body, for example on fighter aircrafts, the airflow is travelling along the body of the aircraft before it reaches the air intake. A boundary layer builds up along the body, something which is not desirable, especially in the part of the flow that supplies the engines. The pressure recovery is lower because of this, something that has a negative effect upon engine thrust. There are, however, ways to prevent the boundary layer from entering the inlet, or at least to minimize the amount that does. It is common to use a boundary layer diverter. It affects the aircraft performance in so many ways. So, it needs some other provision or technology to overcome intake problem in fighter crafts. In the present work, a well-designed compression surface is installed in the entry of the engine intake to redirect boundary layer and create shock wave for getting desired flow in the compressor (When a flow crosses a shock wave, its velocity got reduced, which in term increases pressure). The compression surface is placed at the entry of the diffuser to perform the above mentioned operation. The work extents to, a comparative investigation is proposed for with and without compression surface. ANSYS-Fluent is a commercial CFD code which will be used for performing the simulation and the simulation configuration contains two different Mach speeds (0.7 & 2) with three different angles of attacks (0°, 7.5° and 15°). The simulation results are evaluated to find out pressure recovery in the engine intake between with and without compression surface.