The Study of Flow discharge formula on slit dam
Date Issued
2005
Date
2005
Author(s)
Chen, Ying-Nan
DOI
zh-TW
Abstract
The project proposes to collect the international and domestic literatures and design cases associated with flume experiments to derive the flow discharge model of slit dams and their spillways. The model utilizes the fundamentals of fluid mechanics and open channel mechanics. It employs continuity equation, momentum equation, energy equation, and the method of calculating the energy loss of piers to derive the energy loss associated with the flows between slit dams. The model also takes into account of section contraction, the distance between dams, and the number of dams to formulate the slit dam discharge equation. The flume experimental divides into the flow depth over comb and the flow depth not yet over two parts, setup involves four various distances between the dams and discharge for every slope, three different drops and bed slopes. The 360 set data obtained is analyzed to propose capital result model.
1. In the flow depth over comb or the flow depth not yet over two situaion, energy reduced rate will all be followed to increase as become high to drop, the factor of flow depth is no certain relation in this change to the thing that energy reduced rate.
2. For discharge formula of dam in soil and water conservation manual used in Taiwan area, by way of this project that there is phenomenon underestimated seriously to emerge in discharge formula estimating the slit dam with this discharge formula, it is unsuitable to use for what has been designed the slit dam on the engineering, need to do a revision of Cd value, could be geared to actual circumstances the situation, the relational formula received is as follows:
，which R2=0.88
3. When the flow depth are higher than comb, the formula of traditional check dam can’t represent the discharge of slit dam, with the result of this study, the discharge formula must multiply a correct coefficient to conform to realize situation, get a relationship formula as follows:
，which R2=0.87
Where, Q= the discharge of slit dam(cms); B=dam width(m)
b=comb interval length(m) ;S=bed slope
h=observing water head(m) ;n=numbers of comb
g=acceleration of gravity
Subjects
梳子壩
水槽試驗
能量損失
slit dam
flume experiment
energy loss
Type
thesis
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