Transient formation characteristics of temperature stratified flow in a horizontal water pipe with an injection of hot water from a hole of a pipe
Temperature stratified flow was numerically analyzed in a horizontal pipe. Initially cold water is running and developed in a pipe. From a part of a pipe wall, hot water is injected. Subsequent transient velocity and temperature stratification process was numerically analyzed. This process is a model for such transfer phenomena as follows, i.e., blowing of fresh air into a long tunnel, replacing process of hazardous fluids from a pipeline of an industrial plant with safer fluids, ventilation of a large construction house or ducts, transient combustion process in a tunnel or huge duct, transient flow and temperature characteristics in a canal or river with multiple sub channels. These various cases become more complicated and more serious for the larger scale systems. Temperature stratified flow is everywhere established which makes the prediction difficult. This paper presents transient three-dimensional numerical analyses for a horizontal pipe in which laminar cold water runs steadily. Hot water is injected from a lower side corner of a pipe. Model equations consist of fully three-dimensional balance equations in a cylindrical coordinate. Total tube length computed is 10 times of a pipe diameter d{sub 0}. Hot water inlet hole is 0.4d{sub 0} long in an axial direction and {pi}d{sub 0}/8 in a circumferential direction near the entrance of the system. Reynolds number in a pipe is 1000. Reynolds number of the hot water at the injection hole is 447. Grashof number based on the temperature difference is 5 x 10{sup 7} and Pr = 5.41. Transient three-dimensional velocity profiles and isotherms are presented. The instantaneous water temperature represents oscillatory fluctuation depending on the level in a pipe and on the axial distance from the injection hole. For the tube diameter 0.1m, an average temperature arrived a quasi-steady state after 5 minutes with strong temperature stratification even at 1m from an injection hole. Near the injection hole, hot water makes circumferential convection with oscillatory up and down vortex flow in an axial direction. Warmer water makes stratified flow with faster axial velocity near the top of the tube with much slower axial velocity near the bottom of the tube. These fully three-dimensionally complicated flow and temperature stratification characteristics are presented in various ends view and side views of a long pipe. The importance to note the temperature stratified flow is discussed.
- Research Organization:
- Kyushu Univ., Kasuga (JP)
- OSTI ID:
- 20030474
- Resource Relation:
- Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
- Country of Publication:
- United States
- Language:
- English
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