Study on relationship between thermal stratification and cavity flow in a branch pipe with a closed end. Development of evaluation method for penetration length of cavity flow in branch pipe consisted of vertical and horizontal pipe

This paper describes the characteristics of the cavity flow which appears in a pipe with a closed end, and the development of the evaluation method of a penetration length of cavity flow. The penetration length of a cavity flow in a branch pipe with a closed end was clarified experimentally under the condition that there was a constant flow in the main loop which was connected with a branch pipe, which consist of a vertical and a horizontal pipe. The experiment was carried out for that branch pipe arrangement. In this experiment, the effect of horizontal branch pipe length and diameter, temperature, and fluid velocity in the main loop were clarified. The evaluation method of penetration length of cavity flow into a vertical, LSh, was developed based on the experimental results. This method was consists of two model, i.e. the analysis model for cavity flow and the natural convection which appears in down stream of thermal stratification layer. It was confirmed that the method predicted penetration length of cavity flow well. (author)