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.

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.

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.

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.

Measurements of Rotordynamic Forces on an Artificial Heart Pump Impeller

2007 ◽  
Vol 129 (11) ◽  
pp. 1422-1427 ◽  
Author(s):  
Takayuki Suzuki ◽  
Romain Prunières ◽  
Hironori Horiguchi ◽  
Tomonori Tsukiya ◽  
Yoshiyuki Taenaka ◽  
...  
Keyword(s):  
Artificial Heart ◽  
Journal Bearing ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Fluid Forces ◽  
Heart Pump ◽  
Wide Range ◽  
Artificial Hearts ◽  
Rotordynamic Forces ◽  
Magnetic Drive

In centrifugal pumps for artificial hearts, a magnetic drive with lightly loaded journal bearing system is often used. In such a system, the rigidity of the bearing is small and the impeller usually rotates over the critical speed. In such cases, the rotordynamic fluid forces play an important role for shaft vibration. In the present study, the characteristics of the rotordynamic fluid forces on the impeller were examined. The rotordynamic fluid forces were measured in the cases with/without the whirling motion. It was found that the rotordynamic forces become destabilizing in a wide range of positive whirl. The effect of leakage flow was also examined.

Behavior as a window on physiology: a simple apparatus for recording caterpillar feeding.

1992 ◽  
Vol 262 (6) ◽  
pp. S9 ◽  
Author(s):  
E Bowdan
Keyword(s):  
Feeding Behavior ◽  
Control Mechanisms ◽  
Inexpensive Method ◽  
Simple Apparatus ◽  
Physiological Processes ◽  
Wide Range ◽  
Relationship Of ◽  
The Relationship

Regulation of feeding is a fundamental element of homeostasis. This is reflected in the similarity of control mechanisms in a wide range of animals, including insects and humans. A close examination of feeding behavior can illuminate the physiological processes driving regulation. A simple, inexpensive method for recording fine details of feeding by caterpillars is described. Possible experiments, interpretation of the data, and the relationship of observations to the underlying physiology, are outlined.

Fungal melanins: a review

1998 ◽  
Vol 44 (12) ◽  
pp. 1115-1136 ◽  
Author(s):  
M J Butler ◽  
A W Day
Keyword(s):  
Molecular Biology ◽  
Analytical Methods ◽  
Enzymatic Degradation ◽  
Fundamental Properties ◽  
Wide Range ◽  
Lignin Peroxidases ◽  
Fungal Melanin ◽  
Relationship Of ◽  
The Relationship ◽  
Fungal Melanins

The relationship of polyketide melanogenesis molecular biology to that of nonmelanin-producing pathways in a wide range of fungi and other organisms is discussed. Analytical methods and fundamental properties of melanins are discussed and fungal melanin properties are compared with those of animal and bacterial melanins. The enzymatic degradation of melanins by lignin peroxidases is described.Key words: fungal melanin, polyketide melanin, DHN melanin, melanin degradation, melanin properties, melanin analysis.

Inclusive Design and Usability

2000 ◽  
Vol 44 (38) ◽  
pp. 893-896
Author(s):  
W.S. Green
Keyword(s):  
Inclusive Design ◽  
Wide Range ◽  
User Groups ◽  
Relationship Of ◽  
The Relationship

This introduction to the symposium Inclusive Design and Usability gives an overview of some of the issues and problems facing ergonomists and designers who attempt to provide access to current technologies for a wide range of user groups, particularly those who may be considered disadvantaged or handicapped. The relationship of ergonomics and design is raised.

Ekphrasis

2017 ◽  
Author(s):  
Joel Altman
Keyword(s):  
Early Modern ◽  
Usual Sense ◽  
Early Modern Theatre ◽  
Early Modern English ◽  
Wide Range ◽  
Word Painting ◽  
English Stage ◽  
Relationship Of ◽  
The Relationship ◽  
Flexible Capacity

This chapter examines the use of ekphrasis in early modern theatre, with particular emphasis on its effect on the stage and the relationship of ekphrastic speech to the ongoing action in which it is enunciated. It maps the parameters of ekphrasis on the early modern English stage by considering a few examples of the ways in which ekphrasis instantiates early modern theatricality. It also discusses the expressive potential of ekphrastic speech and its transmission to the listener as well as the ironic uses of ekphrasis as a mode of persuasion, whether directed to oneself, an on-stage auditor, off-stage auditors, or all three. It argues that ekphrasis creates nothing less than what it calls ‘the psyche of the play’ and explains how the unusually flexible capacity of the staged word allows it to be used for a wide range of theatrical techniques, including the usual sense of ‘word-painting’. Finally, it looks at William Shakespeare’s deployment of ekphrasis in his work such asHamlet.

Australian Applied Linguistics in relation to international trends

2010 ◽  
Vol 33 (1) ◽  
pp. 4.1-4.32 ◽  
Author(s):  
Richard B. Baldauf ◽  
Robert B. Kaplan
Keyword(s):  
Text Analysis ◽  
International Association ◽  
Applied Linguistics ◽  
Historical Review ◽  
International Trends ◽  
Diverse Field ◽  
Wide Range ◽  
The World ◽  
Relationship Of ◽  
The Relationship

Applied Linguistics is a diverse field, comprising a substantial number of sub-fields, sub-specialisations and related fields. To see that this is the case one need only examine the various hand- books and encyclopaedic references that have been published in the last ten years to see the wide range of topics that have been covered. As with many professional areas in academia, Applied Linguistics is organised around national organisations, with its international structure being a loose confederation known as the International Association of Applied Linguistics (AILA). Given these diverse academic and structural arrangements, it should not be surprising if academics within different national associations were to cluster around different interests within the field. This study explores the question of what emphases are found in various parts of the world in Applied Linguistics, and in particular, the relationship of Australian Applied Linguistics to international trends using a structural text analysis of abstracts related to Applied Linguistics as well as an historical review of the trends involved.

scholarly journals The unbearable lightness of being alternative: Idealism‐realism and purism‐pragmatism in Greek alternative media

2020 ◽  
Vol 5 (1) ◽  
pp. 103-122
Author(s):  
Dimitra L. Milioni ◽  
Pantelis Vatikiotis
Keyword(s):  
Political Economy ◽  
Alternative Media ◽  
The Political ◽  
Organization Level ◽  
Number Of Factors ◽  
Wide Range ◽  
Dialectical Relationship ◽  
Production Organization ◽  
Relationship Of ◽  
The Relationship

The article explores alternative media sustainability across a wide range of Greek projects. In this regard, it probes into a number of factors related to both the political economy (funding, organization) of these projects and the nature (real/‘imaginary’, broad reach/niche) of the relationship with their communities/audiences. The findings of the research reveal a dynamic and contradictory field regarding alternative media resilience in terms of the dialectical relationship of idealistic/realistic (on the production, organization level) and puristic/pragmatic (on the communication, reach level) features. The article concludes by highlighting the strategies employed by the most successful projects in terms of sustainability in relation to their positioning along the idealism/realism and purism/pragmatism nexus.

Sign in / Sign up

Export Citation Format

Share Document