The Design, Experimentation, and Characterization of a High-Pressure Round-Edged Orifice Plate Test Facility

Orifice plates are commonly found in fluid measurement devices, piping systems, and engines. They are used as flow measurement devices, appear as restrictors in piping, or are used as fuel injectors inside internal combustion engines. While there are equations that predict the discharge coefficient performance for orifice plates, the most accurate estimates are developed empirically from experimental data, or numerical simulations. The focus of this thesis is on a sponsor provided round-edged orifice plate under a range of high-pressure flow conditions, with the goal of characterizing the relationship between pressure difference across the orifice and the discharge coefficient, as well as the effect phenomena like cavitation may have. To perform such measurements, a test facility was designed and instrumented to measure the flow rate through and pressure difference across the orifice plate geometry. Additionally, high-speed video of the orifice plate was collected to determine the presence of a range of fluid phenomena, including cavitation and hydraulic flip. The results show that for the range of pressure differentials tested the orifice plate discharge coefficient is roughly independent of both Reynolds number and cavitation number. Additionally, the asymptotic value of the coefficient is above that predicted for sharp-edged orifice plates and below those for venturi tubes. The high-speed video, recording at frame rates up to 720 fps, shows no evidence of cavitation or hydraulic flip for all experimental pressure differential ranges, 50 to 1200 psid, which indicates that the rounded inlet edge of the orifice delays the onset of cavitation inside the throat of the orifice plate and the flow remains single-phase until exiting. This result, along with the independence of Reynolds number, indicates that for the pressure differential range tested the orifice plate discharge coefficient is only a function of the geometry