摘要: |
The objective of this project is to develop a report to document the study approach and the research results. The report will include a practical design method for estimating average and local velocities in culverts and will describe how the results can be used to develop improved methods for facilitating fish Federal Highway Administration (FHWA) at the Turner-Fairbank Highway Research Center's J. Sterling Jones Hydraulic Research Laboratory in McLean, Virginia. Hydraulic variables will include flow depth, flow condition (laminar, transition and turbulent), Froude number and the variation of flow velocities within the culvert cross-section. Culvert variables will include size and shape, slope, sediment deposits and culvert material. The experiments will be conducted in a new designed culvert test facility where a 15- to 20-foot length of specified culvert geometries will be installed between the headbox and tail box. Only the symmetrical half of the culverts will be modeled allowing larger scale models (1:5). Current FHWA laboratory instrumentation can now achieve much more precise measurements than was possible a few years ago to evaluate these hydraulic characteristics under low flow conditions. An advanced particle image velocimetry (PIV) technology will be used for measuring instantaneous flow fields in the culvert. The particle image velocimetry technique (PIV) is an optical flow diagnostic based on the interaction of light refraction and scattering with inhomogeneous media. |