ACCURATE DISCHARGE COEFFICIENT RELATIONSHIP FOR THE CRUMP WEIR

Achour Bachir; Amara Lyes

Article Details

ACCURATE DISCHARGE COEFFICIENT RELATIONSHIP FOR THE CRUMP WEIR

Authors:

Achour Bachir | Amara Lyes

Publisher:

Université Mohamed Khider de Biskra

Journal:

LARHYSS Journal Vol.20 Issue 1, pp.165-187

Document Type:

Article

Publication Date:

3/2023

Document Language:

English

Document ID (Org No.):

2001912791

pISSN:

2602-7828

Keywords:

Abstract:

 Due to its horizontal crest in the transverse direction and its inclined upstream and downstream faces, whose inclination is well defined, the Crump weir can be classified into the category of triangular longitudinal profile weirs, including the Bazin weir It is an intermediate category between that which includes thin-crested weirs characterized by reduced thickness and that which includes broad-crested weirs that extend over a given length in the streamwise direction
In practice, the Crump weir is preferably used as a sill for several reasons The weir reduces the upstream flow velocity by raising the water level, which reduces or even avoids erosion Additionally, the measurement of the upstream flow depth h, counted above the weir, is carried out with the greatest precision when the device is used as a flow meter
The Crump weir as a flow measuring structure has not been studied from a theoretical point of view, and only experimental observations have enabled it to be calibrated The resulting stage-discharge relationship is not only empirical but also incomplete since the effect of influential parameters, such as h/B, where B is the width of the rectangular approach channel, has not been accounted for, which affects the accuracy of the flow rate calculation Only the effect of the relative elevation of the crest weir P* = P/h on the flow rate was examined on the basis of observations, where P is the elevation of the crest weir The dimensionless parameter P* reflects the influence of the vertical contraction of the flow caused by the weir
In this study, it is proven that the ratio h/B accounts for 235% as an average effect in the calculation of the discharge coefficient Cd and hence of the flow rate Q The refined model describing this effect is yielded based on the analysis of observations available in the literature because current theories are unable to produce a mathematical representation of this effect Unlike h/B, the effect of P* is derived from a rigorous theory based on the energy equation, judiciously transformed into dimensionless terms, along with rational hydraulic concepts Therefore, the discharge coefficient relationship resulting from this study is a semiempirical formula that can be written symbolically in the following form  It is inferred that  is a constant whose appropriate value is estimated to be 08601, while the symbolic functions f1 and f2 are explicitly defined as simple and handy relationships Compared to recent observations, the previous Cd relationship causes a maximum deviation of only 0864%, resulting in the same maximum deviation in the flow rate Q computation Therefore, it can be considered the most accurate and comprehensive Cd relationship ever developed before for the Crump weir working under free overflow conditions This allows the user to estimate the rate Q sought with great certainty and confidence.

Article Details

ACCURATE DISCHARGE COEFFICIENT RELATIONSHIP FOR THE CRUMP WEIR

Authors:

Achour Bachir | Amara Lyes

Publisher:

Université Mohamed Khider de Biskra

Journal:

LARHYSS Journal Vol.20 Issue 1, pp.165-187

Document Type:

Article

Publication Date:

3/2023

Document Language:

English

Document ID (Org No.):

2001912791

pISSN:

2602-7828

Crump weir

stage-discharge relationship

flow measurement

semiempirical approach

discharge coefficient

Issues

Article Details

ACCURATE DISCHARGE COEFFICIENT RELATIONSHIP FOR THE CRUMP WEIR

Authors: Achour Bachir | Amara Lyes

Publisher: Université Mohamed Khider de Biskra

Journal: LARHYSS Journal Vol.20 Issue 1, pp.165-187

Document Type: Article

Publication Date: 3/2023

Document Language: English

Document ID (Org No.): 2001912791

pISSN: 2602-7828

Crump weir

stage-discharge relationship

flow measurement

semiempirical approach

discharge coefficient

Issues

Authors:

Achour Bachir | Amara Lyes

Publisher:

Université Mohamed Khider de Biskra

Journal:

LARHYSS Journal Vol.20 Issue 1, pp.165-187

Document Type:

Article

Publication Date:

3/2023

Document Language:

English

Document ID (Org No.):

2001912791

pISSN:

2602-7828