Through the past decades, people have done a great deal of experiment research on single jet and have got abundant datum, while have not done much on the flow characteristic of multiple jets. In recent years, with the development of industry, the appliance of multiple jets is more and more, in many engineering technique branches all have many jets problems, for example rocket and jet plane in avigation, steam pump, steamer, firebox in dynamical aspect, mixed equiment in chemical engineering, jet component...