JF 17 Thunder Uses a DSI Inlet

DSI Inlet of JF-17 Thunder

The Diverterless Supersonic Inlet (DSI) is a novel air inlet design principle used by modern fighter aircraft to control air flow into their engines. It is a three-dimensional bulge loss without surface layer partition. It consists of a “bump” and a forward-swept inlet cowl. Both work together to divert boundary layer airflow away from the aircraft’s engine. DSIs can be used to replace the intake ramp and inlet cone, which are more complex, heavy and expensive. The purpose of the intake of an aircraft is to supply the engine with a proper airflow during various flight conditions. Characteristics of a good intake design includes provision of high pressure recovery and low distortion.

According to experts, the DSI inlet has three main advantages over conventional inlets. First it adopts a “cone flow” wave rider design, which has a higher total pressure recovery. It improves the stealth performance of the aircraft. Secondly it reduces the drag on the windward side of the aircraft. Third is that no auxiliary intake and exhaust valves are designed. Thus reducing the weight of the aircraft by hundreds of kilograms. It grants the provision of carrying extra load during operations. Overall the DSI inlet has the characteristics of simple structure, light weight, low resistance and invisibility.

So far five modern aircraft designs have successfully integrated DSI. One is F-35 Joint Strike Fighter, and the others are the J-10, JF-17, J-20 and J-31 multi-role fighter aircraft.