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In order to unify the boundary conditions for various pipe elements and to simplify the computer code, the one-dimensional boundary conditions for three-way junction are extended to those for some pipe elements such as a nozzle and an elbow. To examine whether the extended boundary conditions are useful or not, the pulsatile flow through the pipe with the nozzle or elbow are numerically simulated using a Random-Choice Method and then the results are compared with those by the experiments. As a result, good agreement was found between experiments and calculations as long as the pressure histories are concerned and the extension of the boundary conditions is found to be valuable.

Behavior of pressure waves in exhaust pipes of a reciprocating internal combustion engine influences greatly the noise generated at the end of pipe. To find the relation between the flow pattern throughout the exhaust pipe and exhaust noise, a pulsating flow through a pipe with and without a nozzle, the area ratio of the nozzle to the pipe being 0.25, was experimentally examined. The pulsating flow was generated by the rotary valve. The pressure histories at each station along the pipe and the noise generated at the end of the pipe were measured against the different rotational speeds of the rotary valve. The pressures were differentiated with respect to time so that the intensity of the pressure waves was estimated, and wave diagram was constructed. As a result, the relation between the increase and decrease in the intensity of the pressure wave and the rotational speed was found to be related to the arrival time of the compression waves at the rotary valve and the end of pipe.

A pulsatile flow is studied experimentally through a pipe with three-way junction and the results are compared with the numerical ones obtained by a one-dimensional numerical scheme known as a Random-Choice Method. Boundary conditions for three-way junction axe newly introduced in this paper to be adapted to the RCM and are extended to those at a nozzle. As a result, a good agreement was found between experimental and numerical results and especially, the location of the shock wave is captured very well by the RCM with these boundary conditions.

Although the flow through the poppet valves of the four-stroke cycle engine and piston valves and rotary valves of the two-stroke cycle engine is unsteady, because of the periodic area change of the flow passage of the valves, the flow characteristics of these valves is usually evaluated by steady-flow conditions. The author experimented with flow characteristics under steady and unsteady conditions by using a rotary valve, in order to specify the difference between them and to identify the factors that effect this difference. According to the results obtained, inertia of the mass of the fluid in the flow passage of the valve is the most important factor in creating this difference of flow between them. A theoretical analysis of this inertia was found useful in predicting the effect of various parameters on flow through the passage of the valve under an unsteady condition.