The downwash flow velocity ranged from 4.

Experimental diagnostic study has been performed,and results show that the downwash flow had remark able impacts on the aerodynamic performances, characteristic temperatures,and infrared radiation.

It showed that the influences from gyro zero-position,rocket thrust eccentricity,launch mode and downwash flow field caused by helicopter are evident.

A rotor free-wake model including fuselage effects was established to predict the rotor induced velocity flowfield of a real helicopter which has a combined rotor and fuselage configuration,and to provide a calculating method of the downwash flowfield for airborne rocket or missile fire.

Anumerical method usingthe three-dimensional Euler equations is presented to predict the rotor in-ducedvelocity flowfield of a real helicopter and to provide a calculated method on the downwash flowfield forrocket or missile emission on helicopters.

Under the effects of rotor downwash,the high-speed and high-temperature engine jet will cause a considerable change of infrared radiation characterstics of the helicopter.

The results show that the strengthening subtropical high pressure, the momentum transmission of jet stream in the middle-lower troposphere, a violent downdraft from upper air and a sudden intensification of the outer pressure gradient force of the tyhoon are the important factors due to the strong outer w.

Based on FY-2 infrared images and the reanalysis data for six hours of NCEP(1°×1°),the heavy dust storm process occurred on 13 April 2007 in the middle west part of Hexi corridor is analyzed,particularly the cloud head of the descending jet was tracked and the gravitational instability,conditional symmetric instability and conditional instability are diagnosed in detail.