Details

Autor(en) / Beteiligte

• Huang, Xiaodong

Titel

Hydrodynamic study of one dimensional two-phase helium flow

Ort / Verlag

ProQuest Dissertations Publishing

Erscheinungsjahr

1994

Link zum Volltext

• ProQuest

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• This thesis presents the results of experimental and analytical investigations into the hydrodynamics of one dimensional two-phase helium flow. The study includes: pressure drop measurements of two-phase helium flowing in horizontal tubes under various conditions; investigation into the performance of a venturi flowmeter in vertical and horizontal flows; and the development of capacitance probes to measure void fraction in two-phase helium flow. Two-phase helium pressure drop measurements were conducted on two test sections: one with a length of 128.3 cm and ID of 5.3 mm, and the other with length of 75.6 cm and ID of 4.57 mm. Data for pressure drop and void fraction were obtained at mass flowrates from 0.5 g/s to 2.0 g/s under pressures between 0.65 atm and 1.2 atm. Results for the two-phase pressure drop measurements are analyzed in terms of the conventional two-phase pressure drop multiplier, which is found to depend on system pressure, and vapor quality. Mass flow rate does not appear to have an effect on the two-phase frictional multiplier. A slight tube size effect on the two-phase pressure drop multiplier is found at 1.2 atm; however, this effect quickly diminishes as the system pressure reduces. In general, the homogeneous model gives a much better prediction to the frictional multiplier in horizontal two-phase helium flow than the Lockhart-Martinelli correlation. The performance of a venturi flowmeter in two-phase helium flow was investigated by installing two identical venturis with 2.29 mm throat and 4.57 mm inlet diameter in the same flow loop. With one operating in single phase liquid helium and one in two-phase helium, the ratio of the pressure drop across the two venturis is found to be well correlated to vapor quality in both vertical and horizontal two-phase helium flows. Comparison of such a correlation with homogeneous model predictions shows good agreement especially at vapor qualities below $\sim$0.6. Slip ratio in two-phase helium flow is deduced from void fraction data obtained with capacitance probes. The slip ratio is found to decrease toward unity with increasing system pressure and increasing mass flowrate. Comparison of the slip ratio data with theoretical models is also discussed.