952-956The minimum wall pressure coefficient of orifice plate and its wall pressure distribution relating to tunnel’s and dissipater’s safety are important indices for this energy dissipater design. In the present paper, the minimum wall pressure coefficient of sharp-edged orifice plate was analyzed; meanwhile, the characteristics of sharp-edged orifice plate wall pressure distribution were also analyzed. The research result has shown that the minimum wall pressure coefficient was mainly dominated by the contraction ratio of the orifice plate. The less is the contraction ratio of the orifice plate, the larger is the minimum wall pressure coefficient. The effect of orifice plate’ thickness on the minimum wall pressure coefficient was not obvious and could be neglected. When Reynolds number is more than 105, it has little impact on the minimum wall pressure coefficient. Wall pressure begins to drop down dramatically before 0.5D orifice plate, reaches minimum at the end of orifice plate, and then recovers normally when flows arrival at 3D away after orifice plate. An empirical expression was presented to calculate the minimum wall pressure coefficient. Experimental data illuminate that calculation results by using empirical expression coincided with experiment results
