Abstract: In order to ensure the safety of the anti-submarine warfare (ASW) helicopter in dropping torpedo, it is necessary to understand the flow field characteristics in each direction and its effect to the torpedo dropping. Some representative flow measurement technology and methods are compared. By means of the sevenhole probe measurement in complicated condition, the velocities of the flow field are obtained at three different heights and different flying states. Through data analysis, the basic laws of the flow field beneath the helicopter. It indicates that the infection which the flow field causes will not affect the safety of dropping torpedo. At the same time, combined with the theoretic analysis of the produce and movement of the flow field, the reliability of the experiment is validated.

Key words: ASW helicopter, abdomen flow field, seven-hole probe, torpedo dropping safety