Noriaki Nakamura

Thermodynamic Effect on a Cavitating Inducer in Liquid Nitrogen

For experimental investigations of the thermodynamic effect on a cavitating inducer, it is nesessary to observe the cavitation. However, visualizations of the cavitation are not so easy in cryogenic flow. For this reason, we estimated the cavity region in liquid nitrogen based on measurements of the pressure fluctuation near the blade tip. In the present study, we focused on the length of the tip cavitation as a cavitation parameter. Comparison of the tip cavity length in liquid nitrogen (80 K) with that in cold water (296 K) allowed us to estimate the strength of the thermodynamic effect. The degree of thermodynamic effect was found to increase with an increase of the cavity length. The estimated temperature depression caused by vaporization increased rapidly when the cavity length extended over the throat. In addition, the estimated temperature inside the bubble nearly reached the temperature of the triple point when the pump performance deteriorated.Copyright

Theromdynamic Effect on a Cavitating Inducer in Liquid Nitrogen

For experimental investigations of the thermodynamic effect on a cavitating inducer, it is neccesary to observe the cavitation. However, visualizations of the cavitation are not so easy in cryogenic flow. For this reason, we estimated the cavity region in liquid nitrogen based on measurements of the pressure fluctuation near the blade tip. The degree of the thermodynamic effect was found to increase with the increase of the cavity length of the tip cavitation. The estimated temperature depression caused by vaporization increased rapidly when the cavity length extended over the throat. In addition, the estimated temperature inside the bubble nearly reached the temperature of the triple point when the pump performance deteriorated.

Effect of the Casing Configurations on the Inlet Flow in Rocket Pump Inducer

The effects of the inlet casing configurations on unsteady cavitation were examined with a 3-bladed inducer. The inlet flow and cavitation pattern with two casings were visualized using by PIV and high-speed video. It was found that the rotating cavitation would be suppressed when the tip clearance at the inducer inlet was increased. The vortex cavitation in tip leakage flow and cavitation in back flow effected the suppression of the rotating cavitation through the inlet casing configuration.