Abstract:
Ski-jump ramp is of great significance to improve the takeoff performance of carrier based aircraft. However, the ski-jump ramp produces stronger air-wake than that of the flat deck, resulting in unstable air flow above the deck and near the glide line, that can affect the takeoff and landing safety of the carrier based aircraft. Using the DES turbulence model mixed with RANS and LES, CFD computations were performed to simulate air wakes of the flat and ski-jump decks. The comparison shows that there is a huge separation bubble behind the ski-jump ramp, which has a great impact on the air flow on the upper surface of the deck and near the landing glide line, leading to the reduction of the
x-velocity of the wind over the deck as well as the increase of the takeoff and landing speeds of the carrier aircraft. Meanwhile, the amplitude of velocity fluctuations is also increased by the separation bubble, and this brings difficulty in accurate track control of the carrier aircraft. In order to effectively suppress the air wake caused by the ski-jump ramp, the control based on cylindrical vortex generators (CVG) has been proposed. Due to the existence of CVG, the flow around the upper surface of the ski-jump ramp is changed from separated flow to attached flow, and it greatly reduces the fluctuation amplitude of the air flow on the upper surface of the ski-jump deck. Compared to the case without CVG, the
x-velocity of the wind over the deck is increased, and the PSD of the wind velocity fluctuation is reduced by 20 to 40 dB, restored to the same level as that of the flat deck, thus effectively improving the take-off and landing safety of the carrier aircraft.