A Detailed Study of Transom Breaking Waves
Hydromechanics department rept.
NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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Detailed measurements of the turbulent multiphase flow associated with wave breaking present a unique instrumentation challenge. Measurement systems must be capable of high sampling rates, large dynamic ranges, as well as be capable of making measurements in water, air and optically opaque regions. An experiment was performed in on Carriage 2 in the Deep Water Basin at the Naval Surface Warfare Center, Carderock Division, NSWCCD in October 2007 to measure various characteristics of the breaking wave generated from a submerged ship transom. The primary objective of this work was to obtain full-scale qualitative and quantitative flow field data of a large breaking transom wave over a range of conditions, specifically transom drafts and Froude numbers. Several types of measurements were made of the transom stern wave. Sinkage and trim were measured using two string potentiometers. Drag, vertical and side forces were measured using block gages. To quantify the spray and free surface deformation, several techniques were used, including a scanning LiDAR system, laser sheet flow visualization Quantitative visualization or QViz, and Senix Ultrasonic acoustic distance sensors. Additional measurements were made using the Nortek Acoustic Wave and Current AWAC profiler, which measured velocity and acoustic backscatter through the water column. An array of impedance void fraction probes was also used to measure the entrained air at various locations and depths behind the stern.
- Physical and Dynamic Oceanography