Author(s): Albert Molinas; Khalid B. Marcus

Linked Author(s): Albert Molinas, Khalid B. Marcus

Keywords:

Abstract: Techniques are presented to predict the choking phenomenon which occurs in natural and man made waterways with constriction features. The techniques use the energy equation, the momentum principle, and the continuity equation in one dimensional flow derivation; both the form and the friction losses are considered in the study. The different loss coefficients assumed and introduced in the governing equations are extracted and grouped in functional relationships to predict the choking occurrences. Governing equations are transformed to relate a threshold value of Froude number, termed as the limiting Froude number, to the geometry of the constriction feature and to the discharge coefficient for different flow regimes including subcritical and supercritical approach flow conditions. Governing flow equations in constricted channels result in a Froude number termed as the working Froude number. By comparing the limiting and the working Froude numbers, occurrences of choking phenomenon can be predicted. Theoretical derivations are used in conjunction with laboratory data for horizontal board constrictions to develop a more general coefficient of discharge applicable to severe contractions and to estimate the subcritical upstream flow conditions.

DOI: https://doi.org/10.1080/00221689809498615

Year: 1998