Effects of submergence in Montana flumes.

摘要

As part of a continued research project for the Utah Water Research Laboratory and the State of Utah, a study of flow measurement devices is being conducted throughout the state. Initially the project included only measurement devices associated with high-risk dams, but has since been broadened to any measurement structure of interest for water users in the state. The physical dimensions, relative elevations, and flow accuracy were documented for each included device.;After visiting sixteen sites, it was found that fourteen of the measuring devices had incorrect geometries. Of these fourteen, thirteen of them were originally Parshall flumes. A large percentage of Parshall flumes with geometry inaccuracies was also found from previous data collected for this project. One reoccurring issue was that the flumes had not been well maintained and had damage to the walls or floor. Some of these Parshall flumes did not have a diverging downstream section and are referred to as Montana flumes. In these cases, a standard Parshall rating curve was used to determine flow where it did not apply. Some of the flumes that were tested operated regularly under submerged conditions, and no adjustments were made for submergence.;The objective of this research is to determine if Montana flumes (Parshall flumes without a diverging section) operate similarly to fully constructed Parshall flumes under both free-flow and submerged conditions. Laboratory tests were performed in the Utah Water Research Laboratory to determine corrections for submergence. Flow 3D(TM), a computational fluid dynamics (CFD) software program, was also used to develop corrections for a submerged Montana flume. The laboratory results were compared to the computational fluid dynamics results. By using Flow 3D(TM), a reliable numerical process was developed to determine the flow rate in a submerged Montana flume in an effort to expand the results to other seized flumes.