Cut‐Throat Flume Characteristics

Abstract

The characteristics of cut‐throat flow measuring flumes are examined with special attention to scale effects and the transition submergence at which the flow regime changes from undrowned to drowned. Three flumes were tested over a scale range of 1:4. The results for undrowned flumes indicate a small scale effect at low flow rates only. The noted scale effect is completely eliminated by adjusting the data to correct for dissimilar boundary layer growth. The results for drowned flow indicate no scale effect for relative submergences below 0.85. Above this value an apparent scale effect is noted although it is shown to be of little practical consequence. The value of transition submergence is shown to be nonconstant and dependent on the discharge through the structure. A physical explanation for this behavior is put forward. It is concluded that hydraulic model studies of cut‐throat flumes, are feasible provided the submergence is kept below 0.85 and the entrance and exit conditions are modeled correctly in addition to the flume itself.