1996 Fiscal Year Final Research Report Summary
Analysis of flow phenomena in pipes of gravity controlled water drainage systems
| Project/Area Number |
06452291
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Architectural environment/equipment
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| Research Institution | THE UNIVERSITY OF TOKYO |
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Principal Investigator |
KAMATA Motoyasu Graduate School of Engineering, THE UNIVERSITY OF TOKYO Professor, 大学院・工学系研究科, 教授 (70011228)
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| Co-Investigator(Kenkyū-buntansha) |
KURABUCHI Takashi Seience University of Tokyo Faculty of Enfineering, Associate Professor, 工学部, 助教授 (70178094)
CHIDA Yoshitaka Faculty of Engineering, THE UNIVERSITY OF TOKYO Research Associate, 工学部, 助手 (00107559)
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| Project Period (FY) |
1994 – 1996
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| Keywords | gravity controlled water drainage system / drainage stack / pressure distribution in pipe / fluctuation of pressure / peak negative pressure / peak positive pressure |
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| Research Abstract |
The purpose of this study is to develop a design route of stack drainage systems based on prediction of time-averaged and fluctuated pressure distribution of drainage stacks. Each flow portion which affects the pressure variances in stacks is separately modeled and integrated to form overall pressure distributions. A prediction method had been developed until last year, which is applicable to single point steady discharge cases. In order for its extension, a new series of experiments of multiple-point steady discharge were carried out to obtain data for various flow rate ratios and distances of upper and lower flow discharge with almost the same air flow rate, which was controlled by a butterfly valve inserted at stack vent of the drainage systems. A primary analysis of the data suggest that the peak negative pressure values of both upper and lower discharge tend to increase with making lower discharge within the B zone length of the upper discharge. While the peak negative pressure of the upper discharge is virtually the same as the single-point cases and that of lower discharge is almost irrespective of the discharge points if the distance between the upper and lower discharge is sufficiently large. Moreover, it was found that the frictional coefficient of the peak negative pressure of the lower discharge can be expressed as a function of the flow rate ratio of the lower discharge against total discharge flow rate. The B zone length was found to become larger than the single-point discharge, and the relations between the peak negative pressure and its length were expressed as a power law functions with the value of more than 0.7. It was concluded that the pressure distribution for the multiple-discharge cases can be developed by determining empirical constants based on properly designed additional experiments.
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