Abstract
The flow of a mixture of air and water in both horizontal and vertical pipes was studied. Two kinds of pipes were used : a galvanised 1. 009" I. D. pipe and a rough 0. 986" I. D. pipe of a relative roughness k/d= . 0282, together with a vertical glass pipe 0. 977" I. D. The flow types as visualized were found to be bubble and separate flow for horizontal pipes, whilst for vertical pipes the flow types were bubble and slug. The flow was divided into four possible combinations: 1. water turbulent, air turbulent : t. t. flow 2. " viscous, " viscous : v. v. flow 3. " " , " turbulent : v. t. flow 4. " turbulent, " viscous : t. v. flow. Accordingly, the flow was found to be of the t. t. and t. v. types. Equations were derived for determining the fraction of pipe area filled with air. Two different equations were found describing the separate and bubble flow. These equations involved constants which were determined by experiment. They lead to a dimensionless parameter dp T. P/Dp2 which had a definitive relationship with the operating variables. The behaviour of this parameter is different for different types of flow, which was determined experimentally for the t. t. and t. v. flow types. The results were compared with those of other investigators and a fairly satisfactory correlation obtained. A new method for measuring the fraction of pipe area filled with air is presented. The method appeared promising when the results were compared with those obtained by the use of a cine-camera. This method is of great interest since it is fundamental and with further development greater accuracy should be possible.