Question: The WS-15, code name Emei, is a Chinese after burning turbofan engine, a stealth, twinjet, fifth-generation fighter aircraft developed by China's Chengdu Aerospace Corporation for what airforce?
Related documents: [0]  [DOC] The WS-15 (), codename Emei, is a Chinese afterburning turbofan engine designed by the Shenyang Aeroengine Research Institute and manufactured by the Xi'an Aero-Engine Corporation, used to power China's Chengdu J-20 fighter, which would be able to achieve supercruise. [END] 
[1]  [DOC] The Chengdu J-20 () is a stealth, twinjet, fifth-generation fighter aircraft developed by China's Chengdu Aerospace Corporation for the People's Liberation Army Air Force (PLAAF). The J-20 made its maiden flight on 11 January 2011, but the plane was officially revealed on China International Aviation & Aerospace Exhibition in 2016. In March 2017, Chinese media claimed that the aircraft has entered initial operational capability phase with limited service within Air Force. [END] 
Answer: 
People's Liberation Army Air Force
People's Liberation Army Air Force