Influence of Rotational Speed on Thermodynamic Effect in a Cavitating Inducer

2009 ◽  
Author(s):  
Kengo Kikuta ◽  
Yoshiki Yoshida ◽  
Tomoyuki Hashimoto ◽  
Hideaki Nanri ◽  
Tsutomu Mizuno ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Rotational Speed ◽  
Cavity Length ◽  
Cold Water ◽  
Thermodynamic Effect ◽  
Suction Performance ◽  
Temperature Depression

To estimate the influence of velocity on the thermodynamic effect, we conducted experiments in which the inducer rotational speed was changed in liquid nitrogen. The experiments in liquid nitrogen and in cold water allowed us to estimate the amplitude of the thermodynamic effect. In the experiment with lower rotational speed, suction performance was improved. The cavity length at lower rotational speed was shorter than that at higher speed. Thus, we confirmed that the degree of the thermodynamic effect depends on the rotational speed as lower rotational speed suppresses cavity length. Temperature depression was estimated based on a comparison of cavity length in liquid nitrogen and that in water. We found that the degree of temperature depression became smaller when the rotational speed was lower.

Thermodynamic Effect on a Cavitating Inducer in Liquid Nitrogen

2006 ◽  
Vol 129 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Kengo Kikuta ◽  
Satoshi Hasegawa ◽  
Mitsuru Shimagaki ◽  
Takashi Tokumasu
Keyword(s):  
Liquid Nitrogen ◽  
Cavity Length ◽  
Cold Water ◽  
Cavitation Number ◽  
Experimental Investigations ◽  
Thermodynamic Effect ◽  
Blade Tip ◽  
Cryogenic Flow ◽  
The Difference ◽  
Temperature Depression

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 indicator. Comparison of the tip cavity length in liquid nitrogen (80K) with that in cold water (296K) 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 temperature depression was estimated from the difference of the cavitation number of corresponding cavity condition (i.e., cavity length) between in liquid nitrogen and in cold water. 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.

Thermodynamic Effect on a Cavitating Inducer in Liquid Nitrogen

2005 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Kengo Kikuta ◽  
Satoshi Hasegawa ◽  
Mitsuru Shimagaki ◽  
Noriaki Nakamura ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Triple Point ◽  
Cavity Length ◽  
Cold Water ◽  
Experimental Investigations ◽  
Pump Performance ◽  
Thermodynamic Effect ◽  
Blade Tip ◽  
Cryogenic Flow ◽  
Temperature Depression

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.

scholarly journals Influence of Thermodynamic Effect on Blade Load in a Cavitating Inducer

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Kengo Kikuta ◽  
Noriyuki Shimiya ◽  
Tomoyuki Hashimoto ◽  
Mitsuru Shimagaki ◽  
Hideaki Nanri ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Liquid Nitrogen ◽  
Cavity Length ◽  
Cold Water ◽  
Pressure Rise ◽  
Cavitation Number ◽  
Design Parameters ◽  
Trailing Edge ◽  
Thermodynamic Effect ◽  
Blade Tip

Distribution of the blade load is one of the design parameters for a cavitating inducer. For experimental investigation of the thermodynamic effect on the blade load, we conducted experiments in both cold water and liquid nitrogen. The thermodynamic effect on cavitation notably appears in this cryogenic fluid although it can be disregarded in cold water. In these experiments, the pressure rise along the blade tip was measured. In water, the pressure increased almost linearly from the leading edge to the trailing edge at higher cavitation number. After that, with a decrease of cavitation number, pressure rise occurred only near the trailing edge. On the other hand, in liquid nitrogen, the pressure distribution was similar to that in water at a higher cavitation number, even if the cavitation number as a cavitation parameter decreased. Because the cavitation growth is suppressed by the thermodynamic effect, the distribution of the blade load does not change even at lower cavitation number. By contrast, the pressure distribution in liquid nitrogen has the same tendency as that in water if the cavity length at the blade tip is taken as a cavitation indication. From these results, it was found that the shift of the blade load to the trailing edge depended on the increase of cavity length, and that the distribution of blade load was indicated only by the cavity length independent of the thermodynamic effect.

Thermodynamic Effect and Cavitation Performance of a Cavitating Centrifugal Pump

2011 ◽  
Author(s):  
Teiichi Tanaka
Keyword(s):  
Centrifugal Pump ◽  
Liquid Nitrogen ◽  
Cold Water ◽  
Experimental Results ◽  
Flow Coefficient ◽  
Test Setup ◽  
Cavitation Performance ◽  
Thermodynamic Effect ◽  
Delivery Pressure ◽  
Temperature Depression

The thermodynamic effect which affects the cavitation performance of a cavitating centrifugal pump was investigated experimentally using liquid nitrogen. To measure the pump cavitation performance, a test setup which could carry out experiments using both liquid nitrogen and cold water was constructed. The test setup consisted of a suction tank, a test pump, a mass flow meter, a ball valve and pipes. Vacuum-insulated pipes were used. The test pump was a centrifugal type magnetic pump, and two impellers, which differed in cavitation performance, were used in experiments. Cavitation performance using liquid nitrogen or cold water could be obtained from the measurement of the pump suction and delivery pressure, the pump suction and delivery temperature, and the discharge flow rate. And an improvement in pump cavitation performance could be seen when comparing the experimental results from using liquid nitrogen with those from using cold water. The experimental results indicated that cavitation performance using liquid nitrogen was better than that using cold water. This improvement in cavitation performance was thought to be due to the thermodynamic effect of cavitation. And the estimated temperature depression due to the thermodynamic effect decreased with a decreasing flow coefficient. Moreover, it was shown that the estimated temperature depression due to the thermodynamic effect on the low cavitation performance impeller was larger than that on the high cavitation performance impeller at the same flow coefficient.

Thermodynamic Effect on Cavitation Performances and Cavitation Instabilities in an Inducer

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Kengo Kikuta ◽  
Yoshiki Yoshida ◽  
Mitsuo Watanabe ◽  
Tomoyuki Hashimoto ◽  
Katsuji Nagaura ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Temperature Difference ◽  
Cavity Length ◽  
Cold Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Blade Passage ◽  
Thermodynamic Effect

Based on the length of the tip cavitation as an indication of cavitation, we focused on the effect of thermodynamics on cavitation performances and cavitation instabilities in an inducer. Comparison of the tip cavity length in liquid nitrogen (76K and 80K) as working fluid with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect on the cavitations. The degree of thermodynamic effect was found to increase with an increase of the cavity length, particularly when the cavity length extended over the throat of the blade passage. In addition, cavitation instabilities occurred both in liquid nitrogen and in cold water when the cavity length increased. Subsynchronous rotating cavitation appeared both in liquid nitrogen and in cold water. In the experiment using liquid nitrogen, the temperature difference between 76K and 80K affected the range in which the subsynchronous rotating cavitation occurred. In contrast, deep cavitation surge appeared only in cold water at lower cavitation numbers. From these experimental results, it was concluded that when the cavity length extends over the throat, the thermodynamic effect also affects the cavitation instabilities as a “thermal damping” through the unsteady cavitation characteristics.

Thermodynamic Effect on a Cavitating Inducer—Part I: Geometrical Similarity of Leading Edge Cavities and Cavitation Instabilities

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Jean-Pierre Franc ◽  
Guillaume Boitel ◽  
Michel Riondet ◽  
Éric Janson ◽  
Pierre Ramina ◽  
...  
Keyword(s):  
Transit Time ◽  
Cavity Length ◽  
Cold Water ◽  
Rotation Speed ◽  
Leading Edge ◽  
Cavitation Number ◽  
Thermodynamic Effect ◽  
Cavity Closure ◽  
Cavity Development ◽  
Onset Of Cavitation

The thermodynamic effect on a cavitating inducer is investigated from joint experiments in cold water and Refrigerant 114. The analysis is focused on leading edge cavitation and cavitation instabilities, especially on alternate blade cavitation and supersynchronous rotating cavitation. The cavity length along cylindrical cuts at different radii between the hub and casing is analyzed with respect to the local cavitation number and angle of attack. The similarity in shape of the cavity closure line between water and R114 is examined and deviation caused by thermodynamic effect is clarified. The influence of rotation speed on cavity length is investigated in both fluids and analyzed on the basis of a comparison of characteristic times, namely, the transit time and a thermal time. Thermodynamic delay in the development of leading edge cavities is determined and temperature depressions within the cavities are estimated. Thresholds for the onset of cavitation instabilities are determined for both fluids. The occurrence of cavitation instabilities is discussed with respect to the extent of leading edge cavitation. The thermodynamic delay affecting the occurrence of cavitation instabilities is estimated and compared with the delay on cavity development.

Thermodynamic Effect on Sub-Synchronous Rotating Cavitation and Surge Mode Oscillation in a Space Inducer

2009 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Hideaki Nanri ◽  
Kengo Kikuta ◽  
Yusuke Kazami ◽  
Yuka Iga ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Cold Water ◽  
Acoustic Resonance ◽  
Pipe System ◽  
Thermodynamic Effect ◽  
Mode Oscillation ◽  
Cavitation Instability ◽  
Different Temperatures ◽  
Thermodynamic Effects ◽  
The Relationship

The relationship between the thermodynamic effect and sub-synchronous rotating cavitation was investigated with a focus on cavity fluctuations. Experiments on a three-bladed inducer were conducted with liquid nitrogen at different temperatures (74 K, 78K and 83 K) to confirm the dependence of the thermodynamic effects. Sub-synchronous rotating cavitation appeared at lower cavitation numbers in liquid nitrogen at 74 K, the same as in cold water. In contrast, in liquid nitrogen at 83 K, the occurrence of sub-synchronous rotating cavitation was suppressed because of the increase of the thermodynamic effect due to the rising temperature. Furthermore, unevenness of cavity length under synchronous rotating cavitation at 83 K was also decreased by the thermodynamic effect. However, surge mode oscillation occurred simultaneously under this weakened synchronous rotating cavitation. Cavity lengths on the blades oscillated with the same phase and maintained the uneven cavity pattern. It was inferred that the thermodynamic effect weakened the peripheral cavitation instability, i.e., synchronous rotating cavitation, and thus axial cavitation instability, i.e., surge mode oscillation, was easily induced due to the synchronization of the cavity fluctuation with an acoustic resonance in the present experimental inlet-pipe system.

Thermodynamic Effect on Subsynchronous Rotating Cavitation and Surge Mode Oscillation in a Space Inducer

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Yoshiki Yoshida ◽  
Hideaki Nanri ◽  
Kengo Kikuta ◽  
Yusuke Kazami ◽  
Yuka Iga ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Cold Water ◽  
Acoustic Resonance ◽  
Pipe System ◽  
Thermodynamic Effect ◽  
Mode Oscillation ◽  
Cavitation Instability ◽  
Different Temperatures ◽  
Thermodynamic Effects ◽  
The Relationship

The relationship between the thermodynamic effect and subsynchronous rotating cavitation was investigated with a focus on cavity fluctuations. Experiments on a three-bladed inducer were conducted with liquid nitrogen at different temperatures (74, 78, and 83 K) to confirm the dependence of the thermodynamic effects. Subsynchronous rotating cavitation appeared at lower cavitation numbers in liquid nitrogen at 74 K, the same as in cold water. In contrast, in liquid nitrogen at 83 K the occurrence of subsynchronous rotating cavitation was suppressed because of the increase of the thermodynamic effect due to the rising temperature. Furthermore, unevenness of cavity length under synchronous rotating cavitation at 83 K was also decreased by the thermodynamic effect. However, surge mode oscillation occurred simultaneously under this weakened synchronous rotating cavitation. Cavity lengths on the blades oscillated with the same phase and maintained the uneven cavity pattern. It was inferred that the thermodynamic effect weakened peripheral cavitation instability, i.e., synchronous rotating cavitation, and thus axial cavitation instability, i.e., surge mode oscillation, was easily induced due to the synchronization of the cavity fluctuation with an acoustic resonance in the present experimental inlet-pipe system.

scholarly journals An Experimental Investigation of Thermal Effects in a Cavitating Inducer

2004 ◽  
Vol 126 (5) ◽  
pp. 716-723 ◽  
Author(s):  
Jean-Pierre Franc ◽  
Claude Rebattet ◽  
Alain Coulon
Keyword(s):  
Thermal Effects ◽  
Cavity Length ◽  
Cold Water ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Operating Conditions ◽  
Fluid Temperature ◽  
Two Phase ◽  
Thermodynamic Effect ◽  
Comparison Of Tests

The thermal effects which affect the development of leading edge cavitation in an inducer were investigated experimentally using refrigerant R114. For different operating conditions, the evolution of the cavity length with the cavitation parameter was determined from visualizations. The tests were conducted up to two-phase breeding. The comparison of tests in R114 and in cold water allowed us to estimate the amplitude of the thermodynamic effect. The results show that the B-factor depends primarily upon the degree of development of cavitation but not significantly upon other parameters such as the inducer rotation speed or the fluid temperature, at least in the present domain of investigation. These trends are qualitatively in agreement with the classical entrainment theory. In addition, pressure fluctuations spectra were determined in order to detect the onset of cavitation instabilities and particularly of alternate blade cavitation and rotating cavitation. If the onset of alternate blade cavitation appeared to be connected to a critical cavity length, the results are not so clear concerning the onset of rotating cavitation.

Steady Analysis of the Thermodynamic Effect of Partial Cavitation Using the Singularity Method

2006 ◽  
Vol 129 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Satoshi Watanabe ◽  
Tatsuya Hidaka ◽  
Hironori Horiguchi ◽  
Akinori Furukawa ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Cold Water ◽  
Flow Analysis ◽  
Conduction Model ◽  
Cryogenic Fluids ◽  
Singularity Method ◽  
Partial Cavitation ◽  
Thermodynamic Effect ◽  
Unsteady Heat Conduction ◽  
Suction Performance ◽  
Better Than

It is well known that the suction performance of turbopumps in cryogenic fluids is much better than that in cold water because of the thermodynamic effect of cavitation. In the present study, an analytical method to simulate partially cavitating flow with the thermodynamic effect in a cascade is proposed; heat transfer between the cavity and the ambient fluid is modeled by a one-dimensional unsteady heat conduction model under the slender body approximation and is coupled with a flow analysis using singularity methods. In this report, the steady analysis is performed and the results are compared with those of experiments to validate the model of the present analysis. This analysis can be easily extended into unsteady stability analysis for cavitation instabilities such as rotating cavitation and cavitation surge.

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