Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system. In this paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry as-well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has a direct proportional relationship with the product of the inlet pressure, the square of flow rate and two-thirds power exponent of the input power. The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence on the reaction thrust characteristics. In addition, the best values of the half cone angle and the cylinder column length exist to make the reaction thrust reach its maximum under the same inlet conditions.
Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.
