scholarly journals Interaction between Uneven Cavity Length and Shaft Vibration at the Inception of Synchronous Rotating Cavitation

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Y. Yoshida ◽  
Y. Kazami ◽  
K. Nagaura ◽  
M. Shimagaki ◽  
Y. Iga ◽  
...  
Keyword(s):  
Cavity Length ◽  
Experimental Results ◽  
Fluid Force ◽  
Cavitation Instability ◽  
Shaft Vibration ◽  
Relationship Of ◽  
The Relationship

Asymmetric cavitation is known as one type of the sources of cavitation induced vibration in turbomachinery. Cavity lengths are unequal on each blade under condition of synchronous rotating cavitation, which causes synchronous shaft vibration. To investigate the relationship of the cavity length, fluid force, and shaft vibration in a cavitating inducer with three blades, we observed the unevenness of cavity length at the inception of synchronous rotating cavitation. The fluid force generated by the unevenness of the cavity length was found to grow exponentially, and the amplitude of shaft vibration was observed to increase exponentially. These experimental results indicate that the synchronous shaft vibration due to synchronous rotating cavitation is like selfexcited vibrations arising from the coupling between cavitation instability and rotordynamics.

Rotordynamic Forces Acting on Three-Bladed Inducer Under Super-Synchronous/Synchronous Rotating Cavitation

2008 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Masato Eguchi ◽  
Taiichi Motomura ◽  
Masaharu Uchiumi ◽  
Hirotaka Kure ◽  
...  
Keyword(s):  
Cavity Length ◽  
Active Magnetic Bearings ◽  
Fluid Forces ◽  
Wide Range ◽  
Cavitation Instability ◽  
Cryogenic Flow ◽  
Shaft Vibration ◽  
Rotordynamic Forces ◽  
Relationship Of ◽  
The Relationship

Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery. To investigate the relationship of the uneven cavity length and rotordynamic force in a cavitating inducer with three blades, we conducted two experiments. In one, the growth of cavity unevenness at the inception of synchronous rotating cavitation in cryogenic flow was observed, and in the other, the rotordynamic fluid forces in water were examined by using a rotordynamic test stand with active magnetic bearings. Rotordynamic performances were obtained within a wide range of cavitation numbers and whirl/shaft speed ratios included super-synchronous/synchronous rotating cavitation. These experimental results indicate that the shaft vibration due to the rotating cavitation is one type of self-excited vibrations arising from the coupling of cavitation instability and rotordynamics.

Rotordynamic Forces Acting on Three-Bladed Inducer Under Supersynchronous/Synchronous Rotating Cavitation

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yoshiki Yoshida ◽  
Masato Eguchi ◽  
Taiichi Motomura ◽  
Masaharu Uchiumi ◽  
Hirotaka Kure ◽  
...  
Keyword(s):  
Cavity Length ◽  
Active Magnetic Bearings ◽  
Fluid Forces ◽  
Wide Range ◽  
Cavitation Instability ◽  
Cryogenic Flow ◽  
Shaft Vibration ◽  
Rotordynamic Forces ◽  
Relationship Of ◽  
The Relationship

Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery. To investigate the relationship of the uneven cavity length and rotordynamic force in a cavitating inducer with three blades, we conducted two experiments. In one, the growth of cavity unevenness at the inception of synchronous rotating cavitation in cryogenic flow was observed, and in the other, the rotordynamic fluid forces in water were examined by using a rotordynamic test stand with active magnetic bearings. Rotordynamic performances were obtained within a wide range of cavitation numbers, and whirl/shaft speed ratios included supersynchronous/synchronous rotating cavitation. These experimental results indicate that the shaft vibration due to the rotating cavitation is one type of self-excited vibrations arising from the coupling of cavitation instability and rotordynamics.

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.

scholarly journals Photoreduction of Cr(VI) Ions in Aqueous Solutions by UV/ Photocatalytic Processes

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Chih Ming Ma ◽  
Yung Shuen Shen ◽  
Po Hsiang Lin
Keyword(s):  
Aqueous Solutions ◽  
Reaction Rate ◽  
Removal Rate ◽  
Experimental Results ◽  
Order Kinetic ◽  
Solution Ph ◽  
Relationship Of ◽  
The Relationship ◽  
Photocatalytic Processes ◽  
Order Kinetic Equation

This study discussed the photoreduction of Cr(VI) ions in aqueous solutions by UV/TiO2photocatalytic processes under various operational factors. Experimental results showed that the removal rate of Cr(VI) increased with decreasing solution pH values and with increasing dosages of organic compounds, indicating that the recombination rate of electrons and h+can be retarded in the reaction systems by the addition of the scavenger, thus raising the reaction rate of Cr(VI). The relationship of the chemical reaction rate of Cr(VI), TiO2dosage, and changes of Cr(VI) concentration was expressed by the pseudo-first-order kinetic equation. Comparing the experimental results of two different doping metals in modified TiO2photoreduction systems, the removal rate of Cr(VI) by the Ag/TiO2process is larger, possibly because the electron transferring ability of Ag is superior to that of Cu. However, the photoreduction rates of Cr(VI) by modified UV/TiO2processes are worse than those by a nonmodified commercial UV/TiO2process.

Shaping Law and Motion Design in NC-ECM under Effect of Twiste Angle

2011 ◽  
Vol 128-129 ◽  
pp. 1010-1014
Author(s):  
Rui Wu ◽  
Dan Wen Zhang ◽  
Juan Sun
Keyword(s):  
Mathematical Model ◽  
Electrochemical Machining ◽  
Experimental Results ◽  
Working Face ◽  
Relationship Of ◽  
The Mathematical Model ◽  
The Relationship ◽  
Motion Design

The twiste angle has a great effect on shaping law and stability of Numerical Controlled Electrochemical Machining (NC-ECM) process. In order to avoid the disadvantages caused by twiste angle, a methode of study shaping law by dispersing cathode working face in NC-ECM was proposed, and a mathematical model of the shaping law with the effects of twiste angle has been established in this paper. The mathematical model disclosed the relationship of twiste angle β, feeding velocity vf and thickness of removal material h in NC-ECM. Theoretical and experimental results show the the mathematical model of shaping law described in this paper can be considered as a useful reference and is helpful for the analysis of the NC-ECM and general ECM process.

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.

Experimental Design for Characteristics of Fiber Temperature and Strain

2014 ◽  
Vol 551 ◽  
pp. 257-263
Author(s):  
Wei Wen Ye ◽  
Lu Wang ◽  
Qing Guo Shi ◽  
Xue Qin Lei ◽  
Bao Jin Peng
Keyword(s):  
Experimental Design ◽  
Real Time ◽  
Temperature Sensor ◽  
Experimental Results ◽  
Fiber Sensor ◽  
Relationship Of ◽  
The Relationship

This thesis analyses the problems that exist in the fields of fiber-sensor experiment, and real-time draw the diagram of creating a flat about optics-intervene, using computer and camera to replace the traditional observation which are with the eyes to calculate the number of the moving stripes, and using the combination of temperature sensor and computer to replace the traditional thermometer. At the same time, the computer can collect the temperature and the number of moving stripes, and real-time draw the diagram of the temperature and the number of stripes, or draw the relationship of the tension and the number of moving stripes. Experimental results show that the system is stable and reliable, as well as having an age-feeling much more.

scholarly journals Investigating the Relationship between Capability and Motivation of Crowd Worker to Get Better Performance: A Mathematical Approach

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shakir Karim ◽  
Zaheeruddin Asif
Keyword(s):  
Job Performance ◽  
Experimental Results ◽  
Mathematical Approach ◽  
And Performance ◽  
Relationship Of ◽  
Future Work ◽  
The Impact ◽  
The Relationship

The quality of tasks performed by a crowd worker is questionable. Most of the workers are lost if their first work is of low quality, which may influence them to acquire future work in crowdsourcing. Research has highlighted that workers either lack motivation or capability. However, the integrative perspective of capability and motivation in current crowdsourcing research is scarce. There is a need to investigate the relationship of capability and motivation of crowd worker to understand the phenomenon of getting better performance, which ultimately produces a quality outcome. This research aims toward understanding such relationship with mathematical perspective. The traditional renowned and well-accepted theories related to job performance are used for the quantification of motivation, capability, and performance for crowd workers to investigate the impact of capability in relation to the motivation on the performance of crowd worker. Experimental results suggest that formulae will benefit the requester to evaluate the performance of a crowd worker before providing him/her the task and benefit in reducing unemployment in the situation of COVID-19 pandemic.

The Study of LEFP Based on One Part of Semicircle Liner

2013 ◽  
Vol 753-755 ◽  
pp. 1625-1629
Author(s):  
Jie Liu ◽  
Zhong Hua Du ◽  
Rong Zhong Liu ◽  
Yu Cai Dong
Keyword(s):  
Linear Equation ◽  
Explosive Charge ◽  
Analytical Approach ◽  
Experimental Results ◽  
Two Dimensional ◽  
X Ray ◽  
Axis Direction ◽  
Test Velocity ◽  
Relationship Of ◽  
The Relationship

In order to obtain the forming and the velocity of LEFP(Linear Explosively Formed Penetrators) based on one part of semicircle liner, the X-ray radiography and test velocity technology are used to obtain the forming and velocity of LEFP. In this paper, an analytical approach to describe the two-dimensional liner motion of LSCs is addressed firstly at a detonation-point. The relationship of LEFP flight distance can approximate a linear equation to estimate the distance of LEFP before contacting target. Experimental results showed that the shape of LEFP likes a scimitar according to gray image, and LEFP can close around linear explosive charge length axis direction.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Sign in / Sign up

Export Citation Format

Share Document