Abstract

The Periodic Phenomena and the Inerease of Resistance at Detachable to the Form Hydrodynamical Cavitation

G.Kuznetsov (Wave Research Center of the General Physics Institute RAS, Moscow, Russia)

e-mail: kuznetsovgn@mtu-net.ru

In cavitations pipes the acoustic noise and pulsations of pressure on a surface of streamline bodies, and also cross vibrations and factors of resistance to a flow are investigated structure. Is investigated cavitations on circular cylinders, wings of a various structure, disks, spheres and well streamline bodies. Is established, that at detachable it is found out to the form cavitations in spectra of pulsations of factors of normal pressure on a surface of a streamline body and in external cavitations noise sound-scale with the basic frequency similar the Struhals frequency. In particular, at a flow of the cylinder the periodic track such as a track of Carman, even is observed when Reynolds numbers essentially exceeded critical values. Factor of resistance and factor of pulsations of normal pressure simultaneously sharply grows. These sizes become equal to values at Reynolds numbers essentially exceeded critical values. For an explanation of effects the account of a trajectory of movement gas bubbles in a hydro-dynamical field is executed in view of gradients of pressure and pulsations. Is established, that cavitations germs not only extend in a zone of under-pressure and are compressed in a zone of the increased pressure, but also are braked or are accelerated because of interaction with a gradient of pressure along lines of a current. The dimensionless criterion describing this process is received. The explanation of a physical nature of the observable experimental phenomena is given.

Section : 4