Aiming at the requirement of wide range and high precision regulation characteristics of marine diesel engine two-stage turbocharging by-pass valve

the optimization design research of offset special-shaped by-pass valve disc was carried out to realize the equal percentage flow regulation characteristics

which solves the problem of low flow adjustment accuracy of universal quick-open by-pass valve. And the bypass valve with equal percentage flow characteristics can achieve consistent control parameters within the full opening range. According to the different special-shaped valve structures

the flow regulation characteristics were analyzed

and the design method of multi-cross section mixing valve was put forward. Through the flow characteristic test of various valves

the effective adjustment range of multi-cross section mixing valve was verified. The research shows that the flow characteristics of the optimized multi-cross section mixing valve are the closest to the equal percentage flow characteristics. The maximum effective relative opening is 0.73

which is 2.6 times that of the general plat by-pass valve. The gain change rate is reduced and the regulation accuracy is greatly improved. It shows that the multi-cross section mixing valve can significantly improve the regulation characteristics of the boost pressure

and can effectively and smoothly control the boost pressure of the adjustable two-stage turbocharging system.