关键词: servo valve, prestage, turbulent jet, deflector jet

Abstract: In view of the complicated structure of the deflector-jet mechanism, a mathematical model based on the turbulent jet flow theory in the deflector-jet amplifier is proposed. Considering the energy transformation and momentum variation, an equation of the flow velocity distribution at the key fluid region is established to describe the morphological changes of the fluid when it passes through the deflector and jets into the receiver. Moreover, the process is segmented into four stages. According to the research results, the oil enters the deflector and impinges with the side wall. Then one part of the oil's flow velocity decreases and a high pressure zone is formed by the oil accumulation, the other part of the oil reverses out of the deflector along the side wall. Prior to entering the receiver, the flow is a kind of plane impinging jet. Virtually, the working pressure of the receiver is generated by the impact force, while the high speed fluid flows out of the receiver and forms a violent vortex, which generates negative pressure and causes the oil to be gasified. Compared with the numerical simulation results, the turbulent jet model that can effectively describe the characteristics of the deflector-jet mechanism is accurate. In addition, the calculation results of the prestage pressure characteristic have been verified by experiments.

Key words: servo valve, prestage, turbulent jet, deflector jet