Thermodynamic Effect on Rotating Cavitation in an Inducer

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Yoshiki Yoshida ◽  
Yoshifumi Sasao ◽  
Mitsuo Watanabe ◽  
Tomoyuki Hashimoto ◽  
Yuka Iga ◽  
...  
Keyword(s):  
Cavity Length ◽  
Cavity Growth ◽  
Cavitation Number ◽  
Liquid Temperature ◽  
Cryogenic Fluids ◽  
Thermodynamic Effect ◽  
Different Temperatures ◽  
Critical Cavitation ◽  
Thermal Imbalance ◽  
The Relationship

Cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances in turbomachines due to the delay of cavity growth. The relationship between the thermodynamic effect and cavitation instabilities, however, is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation appeared in the turbopump inducer, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K, and 83 K) with a focus on the cavity length. At higher cavitation numbers, supersynchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect.

Thermodynamic Effect on Rotating Cavitation in an Inducer

2007 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Yoshifumi Sasao ◽  
Mitsuo Watanabe ◽  
Tomoyuki Hashimoto ◽  
Yuka Iga ◽  
...  
Keyword(s):  
Cavity Length ◽  
Cavity Growth ◽  
Speed Ratio ◽  
Thermodynamic Effect ◽  
Cavitation Instability ◽  
Different Temperatures ◽  
Shaft Vibration ◽  
Critical Cavitation ◽  
Thermal Imbalance ◽  
The Relationship

Rotating cavitation in inducers is known as one type of cavitation instability, in which an uneven cavity pattern propagates in the same direction as the rotor with a propagating speed ratio of 1.0–1.2. This rotating cavitation causes shaft vibration due to the increase of the unsteady lateral load on the inducer. On the other hand, cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances due to the delay of cavity growth. However, the relationship between the thermodynamic effect and cavitation instabilities is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K and 83 K) with a focus on the cavity length. At higher cavitation numbers, super-synchronous rotating cavitation (Super-SRC) occurred at the critical cavity length of Lc/h ≅ 0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation (SRC) occurred at the critical cavity length of Lc/h ≅ 0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect.

Influence of Thermodynamic Effect on Synchronous Rotating Cavitation

2007 ◽  
Vol 129 (7) ◽  
pp. 871-876 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Yoshifumi Sasao ◽  
Kouichi Okita ◽  
Satoshi Hasegawa ◽  
Mitsuru Shimagaki ◽  
...  
Keyword(s):  
Cavity Length ◽  
Cavity Growth ◽  
Head Loss ◽  
Liquid Temperature ◽  
Fluid Force ◽  
Cryogenic Fluids ◽  
Thermodynamic Effect ◽  
Cavitation Instability ◽  
Different Temperatures ◽  
Thermal Imbalance

Synchronous rotating cavitation is known as one type of cavitation instability, which causes synchronous shaft vibration or head loss. On the other hand, cavitation in cryogenic fluids has a thermodynamic effect on cavitating inducers because of thermal imbalance around the cavity. It improves cavitation performances due to delay of cavity growth. However, relationships between the thermodynamic effect and cavitation instabilities are still unknown. To investigate the influence of the thermodynamic effect on synchronous rotating cavitation, we conducted experiments in which liquid nitrogen was set at different temperatures (74K, 78K, and 83K). We clarified the thermodynamic effect on synchronous rotating cavitation in terms of cavity length, fluid force, and liquid temperature. Synchronous rotating cavitation occurs at the critical cavity length of Lc∕h≅0.8, and the onset cavitation number shifts to a lower level due to the lag of cavity growth by the thermodynamic effect, which appears significantly with rising liquid temperature. Furthermore, we confirmed that the fluid force acting on the inducer notably increases under conditions of synchronous rotating cavitation.

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 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.

Inducer Design Optimization to Improve its Suction Performance

2019 ◽  
Author(s):  
Yushi Nakamura ◽  
Marek Lubieniecki ◽  
Kentarou Hayashi ◽  
Yutaka Kawata ◽  
Masahiro Miyabe ◽  
...  
Keyword(s):  
Response Surface ◽  
Design Space ◽  
Cavitation Number ◽  
Design Parameters ◽  
Baseline Design ◽  
Starting Point ◽  
Blade Shape ◽  
Critical Cavitation ◽  
Suction Performance ◽  
The Relationship

Abstract The purpose of this paper is to present optimization method of an inducer blade shape to improve its suction performance and clarify the relationship between pump performance and design parameters. In order to conduct the optimization process a response surface based optimization framework was established. Baseline was designed in previous research [1]. The inducers were 3Dprinted in ABS plastic and their wetted and cavitating characteristics were measured. It was confirmed that the optimized inducer can maintain its wetted performance at lower cavitation numbers. A response surface is a mathematical model that approximates the relationship between the input parameters and the objective function from a finite number of learning points within the design space. The design space was defined by four parameters: sweep angle, sweep radius, incidence angle and blade solidity at the tip that controlled the blade shape. The performance of each design was evaluated with a CFD simulation established in a commercial solver. The optimization goal was to minimize the critical cavitation number that corresponds to a 5% drop of pressure increase through the pump due to cavitation. A starting point of the optimization was the industrial pump designed by a Japanese company Teral [1]. The results of the numerical optimization show that the critical cavitation number was decreased by 17.6% with respect to the baseline design. In the experimental results, an average improvement of 15.4% was achieved.

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 Effects on Developed Cavitation

1975 ◽  
Vol 97 (4) ◽  
pp. 507-513 ◽  
Author(s):  
J. W. Holl ◽  
M. L. Billet ◽  
D. S. Weir
Keyword(s):  
Cavity Length ◽  
Cavitation Number ◽  
Measured Temperature ◽  
Cavity Pressure ◽  
Dimensionless Form ◽  
Dimensionless Numbers ◽  
Thermodynamic Effect ◽  
Thermodynamic Effects ◽  
Temperature And Pressure ◽  
Temperature Depression

The results of an investigation of thermodynamic effects are presented. Distributions of temperature and pressure in a developed cavity were measured for zero- and quarter-caliber ogives. A semiempirical entrainment theory was developed to correlate the measured temperature depression, ΔT, in the cavity. This theory correlates ΔTmax expressed in dimensionless form as the Jakob number in terms of the dimensionless numbers of Nusselt, Reynolds, Froude, and Pe´cle´t, and dimensionless cavity length, L/D. The results show that in general ΔT increases with L/D and temperature and the cavitation number based on measured cavity pressure is a function of L/D for a given model contour, independent of the thermodynamic effect.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

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