Academic literature on the topic 'Cavitation facility'
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Journal articles on the topic "Cavitation facility"
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Cervone, Angelo, Cristina Bramanti, Emilio Rapposelli, and Luca d’Agostino. "Thermal Cavitation Experiments on a NACA 0015 Hydrofoil." Journal of Fluids Engineering 128, no. 2 (September 13, 2005): 326–31. http://dx.doi.org/10.1115/1.2169808.
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The present paper illustrates the main results of an experimental campaign conducted in the Thermal Cavitation Tunnel of the Cavitating Pump Rotordynamic Test Facility (CPRTF) at Centrospazio/Alta S.p.A. Experiments were carried out on a NACA 0015 hydrofoil at various incidence angles, cavitation numbers, and freestream temperatures, in order to investigate the characteristics of cavitation instabilities and the impact of thermal cavitation effects. Measured cavity length, surface pressure coefficients, and unsteady pressure spectra are in good agreement with the data available in the open literature and suggest the existence of a strong correlation between the onset of the various forms of cavitation and instabilities, the thermal cavitation effects, and the effects induced by the presence of the walls of the tunnel. Further analytical investigations are planned in order to provide a better interpretation of the above results.
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Cervone, Angelo, Cristina Bramanti, Lucio Torre, Domenico Fotino, and Luca d’Agostino. "Setup of a High-Speed Optical System for the Characterization of Flow Instabilities Generated by Cavitation." Journal of Fluids Engineering 129, no. 7 (January 15, 2007): 877–85. http://dx.doi.org/10.1115/1.2742738.
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The present paper illustrates the setup and the preliminary results of an experimental investigation of cavitation flow instabilities carried out by means of a high-speed camera on a three-bladed inducer in the cavitating pump rotordynamic test facility (CPRTF) at Alta S.p.A. The brightness thresholding technique adopted for cavitation recognition is described and implemented in a semi-automatic algorithm. In order to test the capabilities of the algorithm, the mean frontal cavitating area has been computed under different operating conditions. The tip cavity length has also been evaluated as a function of time. Inlet pressure signal and video acquisitions have been synchronized in order to analyze possible cavitation fluid-dynamic instabilities both optically and by means of pressure fluctuation analysis. Fourier analysis showed the occurrence of a cavity length oscillation at a frequency of 14.7Hz, which corresponds to the frequency of the rotating stall instability detected by means of pressure oscillation analysis.
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DUTTWEILER, M. E., and C. E. BRENNEN. "Surge instability on a cavitating propeller." Journal of Fluid Mechanics 458 (May 10, 2002): 133–52. http://dx.doi.org/10.1017/s0022112002007784.
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This study details experiments investigating a previously unrecognized surge instability on a cavitating propeller in a water tunnel. The surge instability is explored through visual observation of the cavitation on the propeller blades and in the tip vortices. Similarities between the instability and previously documented cavitation phenomena are noted. Measurements of the radiated pressure are obtained, and the acoustic signature of the instability is identified. The magnitudes of the fluctuating pressures are very large, presumably capable of producing severe hull vibration on a ship.The origins of this instability are explored through separate investigation of the cavitation dynamics and the response of the water tunnel to volumetric displacement in the working section. Experiments are conducted to quantify the dynamics of the propeller cavitation. Finally, a model is developed for the complete system, incorporating both the cavitation and facility dynamics. The model predicts active system dynamics (linked to the mass flow gain factor familiar in the context of pump dynamics) and therefore potentially unstable behaviour for two distinct frequency ranges, one of which appears to be responsible for the instability.
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OKADA, Tsunenori, Yoshiro IWAI, and Hiroyuki MORl. "Cavitation bubble collapse pressures in a venturi facility." Transactions of the Japan Society of Mechanical Engineers Series B 55, no. 511 (1989): 579–84. http://dx.doi.org/10.1299/kikaib.55.579.
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Wan, Tao, Takashi Naoe, Hiroyuki Kogawa, Masatoshi Futakawa, Hironari Obayashi, and Toshinobu Sasa. "Numerical Study on the Potential of Cavitation Damage in a Lead–Bismuth Eutectic Spallation Target." Materials 12, no. 4 (February 25, 2019): 681. http://dx.doi.org/10.3390/ma12040681.
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To perform basic Research and Development for future Accelerator-driven Systems (ADSs), Japan Proton Accelerator Research Complex (J-PARC) will construct an ADS target test facility. A Lead–Bismuth Eutectic (LBE) spallation target will be installed in the target test facility and bombarded by pulsed proton beams (250 kW, 400 MeV, 25 Hz, and 0.5 ms pulse duration). To realize the LBE spallation target, cavitation damage due to pressure changes in the liquid metal should be determined, preliminarily, because such damage is considered to be very critical, from the viewpoint of target safety and lifetime. In this study, cavitation damage due to pressure waves caused by pulsed proton beam injection and turbulent liquid metal flow, were studied, numerically, from the viewpoint of single cavitation bubble dynamics. Specifically, the threshold of cavitation and effects of flow speed fluctuation on cavitation bubble dynamics, in an orifice structure, were investigated in the present work. The results showed that the LBE spallation target did not undergo cavitation damage, under normal nominal operation conditions, mainly because of the long pulse duration of the pulsed proton beam and the low liquid metal flow velocity. Nevertheless, the possibility of cavitation damage in the orifice structure, under certain extreme transient LBE flow conditions, cannot be neglected.
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Majkowska, Beata, and Waldemar Serbiński. "Cavitation Wearing of the SUPERSTON Alloy after Laser Treatment at Cryogenic Conditions." Solid State Phenomena 165 (June 2010): 306–9. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.306.
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The purpose of this paper is to demonstrate the method of laser remelting at cryogenic conditions of the SUPERSTON alloy and its influence on microstructure and cavitation wearing. The cavitation test was performed using the rotating disc facility in IPM PAN Gdansk. During the cavitation test, the mass loss of the material with different parameters of laser remelting was determined. Surface and cross-section microstructure of the SUPERSTON alloy after laser treatment and cavitation test were observed by scanning electron microscope. The cavitation resistance of the remelted SUPERSTON alloy was approximately 40% higher in comparison to the base material.
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Wetzel, J. M., and R. E. A. Arndt. "Hydrodynamic Design Considerations for Hydroacoustic Facilities: Part II—Pump Design Factors." Journal of Fluids Engineering 116, no. 2 (June 1, 1994): 332–37. http://dx.doi.org/10.1115/1.2910276.
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The St. Anthony Falls Hydraulic Laboratory has been involved in the hydrodynamic design of large cavitation facilities, which require a high performance axial flow pump that is cavitation free to meet stringent design conditions. As cavitation has been shown to be the largest noise source in an otherwise well designed facility, it must be eliminated for the design range of flow conditions. To reduce the possibility of blade cavitation it is desirable to have a near uniform, or at least, a near symmetrical approach velocity distribution at the pump inlet. The design of flow facilities to achieve such an inflow was the subject of extensive investigations. These investigations consisted of both numerical and physical modeling of critical components in the test loop. The influence of these components, which included the contraction, diffuser, and turning vanes was carefully documented. The combination of the two modeling techniques will be demonstrated as an effective design tool for a high performance, hydrodynamic test facility.
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Szkodo, Marek. "Influence of Cavitation Intensity on the Relative Cavitation Resistance of Laser Processed C45 Carbon Steel." Solid State Phenomena 165 (June 2010): 189–94. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.189.
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This work presents investigations of relative cavitation resistance of carbon steel (C45) at the initial stage of erosion, after melting its surface by 6 kW CO2 laser beam. The research work was carried out on the rotating disk facility. Three areas were determined on the surface of investigated sample. Each area was eroded with different intensity. The procedures were elaborated for calculation of resistance of processed surface to plastic deformation under cavitation loading and of relative intensity of cavitation using image analysis of monochromatic picture of eroded surface. The results indicate that increase of cavitation loading intensity results in decrease of relative cavitation resistance.
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Manzana, Madalina Elena, Brandusa Ghiban, Ilare Bordeaşu, Nicolae Ghiban, Mihai Marin, and Florin Miculescu. "Structural Analysis of Steels by Cavitation Erosion." Key Engineering Materials 583 (September 2013): 28–31. http://dx.doi.org/10.4028/www.scientific.net/kem.583.28.
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Cavitation is an important factor in many areas of science and engineering, including acoustics, chemistry and hydraulics. In this paper the authors analyze the structural analysis of cavitation damages in two steel. The cavitation erosion tests were carried out in a magnetostrictive facility, in Timisoara Hydraulic Machinery Laboratory, in according with ASTM G32-85, using as cavitant liquid drink water at 20 10C. After quantitative and qualitative investigations structural features were put in evidence on experimental steel
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Coutier-Delgosha, O., A. Dazin, G. Caignaert, and G. Bois. "Analysis of Cavitation Instabilities in a Four-Blade Inducer." International Journal of Rotating Machinery 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/213907.
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The cavitating behavior of a four-blade inducer tested in the LML laboratory large test facility is considered in the present paper. Experimental investigations based on unsteady pressure measurements and records from a six-component balance mounted on the inducer shaft are performed. Spectral analysis of the signals enables to detect several characteristic frequencies related to unbalanced two-phase flow patterns. The objective of the present paper is the understanding of the physical phenomena associated to these frequencies. Therefore, wavelet decomposition, flow visualizations, and direct analysis of the high-frequency force, moment, and pressure signals are applied. Results at nominal flow rate only are considered. Not only classical unbalanced cavitation patterns, but also unexpected flow organizations are discussed.
Dissertations / Theses on the topic "Cavitation facility"
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Добрунов, Дмитро Євгенійович. "Технологія комплексної переробки соняшникової макухи з безлушпинного ядра." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21793.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.18.06 – технологія жирів, ефірних масел і парфумерно-косметичних продуктів. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2016.
Дисертацію присвячено науковому обґрунтуванню технології комплексної переробки соняшникової макухи з безлушпинного ядра.
Встановлено залежність ступеню вилучення олії і хлорогенової кислоти з соняшникової макухи безлушпинного ядра від складу розчинника, температури та тривалості екстрагування у кавітаційній установці та отримано математичний опис цього процесу у вигляді регресійного рівняння. Виявлено антиоксидантні властивості сухих речовин екстрактів соняшникової макухи безлушпинного ядра. Показано, що досліджені екстракти інгібують ланцюгові вільно-радикальні реакції окиснення. Розроблено перспективну технологію комплексної переробки соняшникової макухи з безлушпинного ядра, за якою можна отримати: олію екстракційну, шрот (або борошно) та жиророзчинний рослинний антиоксидант. Результати роботи впроваджені на ТОВ "Нові енергозберігаючі технології" (м. Херсон), ПАТ "Харківська бісквітна фабрика" (м. Харків) та в навчальний процес кафедри технології жирів та продуктів бродіння НТУ "ХПІ".Thesis for a candidate of technical sciences degree. Speciality 05.18.06 − fats, essential oils and perfume-cosmetic products technology − National Technical University "Kharkiv Polytechnic Institute". Ministry of Education and Science of Ukraine, Kharkiv, 2016. The dissertation is devoted to the basis of technology of complex processing of sun-flower cakes obtained from dehulled sunflower kernels. During the work it was ascertained that sunflower oil and chlorogenic acid extraction rates depend on solvent type, temperature, and extraction time in the cavitation facility. The regression equations for the abovementioned processes were derived. Antioxidant properties of solids extracts obtained from dehulled sunflower kernels (SE) were discovered. It was shown that all of the investigated SE terminate the chain reactions during the propagation step. Complex technology of sunflower cakes processing obtained from dehulled sunflow-er kernels was designed. This technology allows obtaining of extracted oil, sunflower meal (or proteinrich flour), and fat-soluble antioxidant. The results of the work are adopted at "New Energy-Efficient Technologies", LLC, "Kharkiv Biscuit Factory", OJSC, and implemented in the educational process at the Department of Technology of Fats and Fermentation Products of NTU "KhPI".
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Добрунов, Дмитро Євгенійович. "Технологія комплексної переробки соняшникової макухи з безлушпинного ядра." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21784.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.18.06 – технологія жирів, ефірних масел і парфумерно-косметичних продуктів. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2016.
Дисертацію присвячено науковому обґрунтуванню технології комплексної переробки соняшникової макухи з безлушпинного ядра.
Встановлено залежність ступеню вилучення олії і хлорогенової кислоти з соняшникової макухи безлушпинного ядра від складу розчинника, температури та тривалості екстрагування у кавітаційній установці та отримано математичний опис цього процесу у вигляді регресійного рівняння. Виявлено антиоксидантні властивості сухих речовин екстрактів соняшникової макухи безлушпинного ядра. Показано, що досліджені екстракти інгібують ланцюгові вільно-радикальні реакції окиснення. Розроблено перспективну технологію комплексної переробки соняшникової макухи з безлушпинного ядра, за якою можна отримати: олію екстракційну, шрот (або борошно) та жиророзчинний рослинний антиоксидант. Результати роботи впроваджені на ТОВ "Нові енергозберігаючі технології" (м. Херсон), ПАТ "Харківська бісквітна фабрика" (м. Харків) та в навчальний процес кафедри технології жирів та продуктів бродіння НТУ "ХПІ".Thesis for a candidate of technical sciences degree. Speciality 05.18.06 − fats, essential oils and perfume-cosmetic products technology − National Technical University "Kharkiv Polytechnic Institute". Ministry of Education and Science of Ukraine, Kharkiv, 2016. The dissertation is devoted to the basis of technology of complex processing of sun-flower cakes obtained from dehulled sunflower kernels. During the work it was ascertained that sunflower oil and chlorogenic acid extraction rates depend on solvent type, temperature, and extraction time in the cavitation facility. The regression equations for the abovementioned processes were derived. Antioxidant properties of solids extracts obtained from dehulled sunflower kernels (SE) were discovered. It was shown that all of the investigated SE terminate the chain reactions during the propagation step. Complex technology of sunflower cakes processing obtained from dehulled sunflow-er kernels was designed. This technology allows obtaining of extracted oil, sunflower meal (or proteinrich flour), and fat-soluble antioxidant. The results of the work are adopted at "New Energy-Efficient Technologies", LLC, "Kharkiv Biscuit Factory", OJSC, and implemented in the educational process at the Department of Technology of Fats and Fermentation Products of NTU "KhPI"
Book chapters on the topic "Cavitation facility"
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Adams, Maurice L. "Swiss Federal Institute Cavitation Research Facility at EPFL Lausanne." In Rotating Machinery Research and Development Test Rigs, 91–97. Boca Raton : Taylor & Francis, CRC Press, [2017]: CRC Press, 2017. http://dx.doi.org/10.1201/9781315116723-8.
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"The Effect of Gas Content on Cavitation Shedding and Test Facility Dynamics." In Proceedings of the 10th International Symposium on Cavitation (CAV2018), 995–1002. ASME Press, 2018. http://dx.doi.org/10.1115/1.861851_ch190.
Full textConference papers on the topic "Cavitation facility"
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Ito, Yutaka, Naoki Tani, Yuto Kurishita, Satoshi Kitano, and Takao Nagasaki. "New Visualization Test Facility for Liquid Nitrogen and Water Cavitation in Rotating Inducer." In 8th International Symposium on Cavitation. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2826-7_104.
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Rapposelli, Emilio, Angelo Cervone, Cristina Bramanti, and Luca d’Agostino. "Thermal Cavitation Experiments on a NACA 0015 Hydrofoil." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45006.
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The present paper illustrates the main results of an experimental campaign conducted in the Thermal Cavitation Tunnel of the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Centrospazio. Experiments were carried out on a NACA 0015 hydrofoil at various incidence angles, cavitation numbers and freestream temperatures, in order to investigate the characteristics of cavitation instabilities and the impact of thermal cavitation effects. Measured cavity length, surface pressure coefficients and unsteady pressure spectra are in good agreement with the data available in the open literature and suggest the existence of a strong correlation between the onset of the various forms of cavitation and instabilities, the thermal cavitation effects, and the effects induced by the presence of the walls of the tunnel. Further analytical investigations will be carried out in order to provide a better interpretation of the above results.
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Pasini, Angelo, Lucio Torre, Angelo Cervone, and Luca d’Agostino. "Experimental Characterization of Thermal Cavitation Effects on Space Rocket Axial Inducers." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-06043.
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The paper shows the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at ALTA S.p.A., aimed at characterizing the cavitation thermal effects on two tapered-hub, variable-pitch inducers, designated as DAPAMITO. The semi-empirical method proposed by Ruggeri and Moore for scaling the thermal cavitation effects has been successfully applied and, consequently, a further validation of this method has been provided. The influence of the temperature on the intensity of the performance degradation associated with the attached cavitation instability has been identified as a new typology of cavitation thermal effects. In this case, the inhibition of the bubble growth due to thermal effects can be detected by the reduction of the performance degradation usually associated with this type of instability.
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Ahuja, Vineet, and Ashvin Hosangadi. "Simulations of Cavitation in Orifice and Venturis." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26639.
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Computational simulations can play an integral role in supporting testing and developmental activities by identifying and characterizing flow instabilities. However, the diversity of flow regimes and instability mechanisms place very stringent requirements on any computational framework that could be used for such analyses. For example, the identification of dominant frequencies associated with flow instabilities in such systems requires high order numerics, advanced turbulence modeling capabilities, sophisticated grid topologies to resolve local physics in complex geometries, embedded models for unsteady cavitation, capture thermal effects in cryogenic fluids, and dynamic motion of feed system components such as valves. In this paper, we discuss simulations of cavitating instabilities in feed system components and control elements used in the E-1 test facility at NASA Stennis Space Center (SSC). The two different feed system components considered here are: (a) orifice and (b) flow control venturi that is attached to a 90 degree turning duct. These two components represent the two disparate regimes of cavitating flows: the orifice is representative of traveling cavitation class of flows commonly observed in tip vortices of propeller blades, whereas the venturi represents a sheet cavitation type problem with periodic shedding of vaporous clouds from this well developed cavity. The simulations are performed with a well validated cryogenic cavitation model that takes into account evaporative cooling and other associated thermal effects.
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Tan, David Y., Rinaldo L. Miorini, Jens Keller, and Joseph Katz. "Flow Visualization Using Cavitation Within Blade Passage of an Axial Waterjet Pump Rotor." In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72108.
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Cavitation phenomena within an axial waterjet pump, AxWJ-2 [1,2] operating at and below the best efficiency point (BEP) are investigated using high-speed imaging. The purpose of these preliminary observations is to provide an overview of the physical appearance of several forms of cavitation under varying flow and pressure conditions. These observations provide a motivation for upcoming detailed velocity and turbulence measurements. The experiment is conducted using a transparent pump installed in an optically index-matched facility, which facilitates unobstructed visual access to the pressure and suction sides of the rotor and stator blade passages. By varying the cavitation index within the facility, the observations follow the gradual development of cavitation from inception level to conditions under which the cavitation covers the entire blade. Cavitation appears first in the tip gap, as the fluid is forced from the pressure side (PS) to the suction side (SS) of the rotor blade. Bubbly streaks start at the SS corner, and penetrate into the passage, and are subsequently entrained into the tip leakage vortex (TLV) propagating in the passage. Sheet cavitation also develops along the SS of the rotor leading edge and covers increasing fractions of the blade surface with decreasing cavitation number. At BEP conditions, the sheet is thin. Below BEP, the blade loading increases as a result of an increase in the incidence angle of the flow entering the passage relative to the blade. Consequently, the backward leakage flow also increases, further increasing the incidence angle in the tip region, and thickening the sheet cavitation there. Consistent with previous observations on swept hydrofoils, a re-entrant jet that flows radially outward develops at the trailing edge of the sheet cavitation. Only near the tip corner the trailing edge of the sheet cavitation is opened as the radial re-entrant flow is entrained into the TLV, forming an unstable and noisy spiraling pattern. Within a certain range of cavitation indices, when the sheet cavitation length at the blade tip extends to about 50–60% of the blade spacing, the sheet cavitation on every other blade begins to expand and contract rapidly, generating loud low-frequency noise. With further decrease in pressure, persistent alternating cavitation occurs, namely, the cavitating region on one blade becomes much larger than that in the neighboring one. The mechanisms involved and associated instabilities are discussed based on previous analyses performed for inducers. As the cavitation number is lowered even further, the sheet cavitation on the “heavily-cavitating” blade grows, and eventually passes the trailing edge of the rotor blade. At this condition, cavitation begins again to expand and contract rapidly on the “less-cavitating” blade, covering a significant portion of SS surface. At a lower pressure, all the blades cavitate, with the sheet cavitation covering the entire SS surface of the rotor blade. The large cavities on alternate rotor blade surfaces re-direct flow into the neighboring passages with the smaller cavities. As a result, there is a lower flow rate in the passage with the larger cavitation and higher flow rate in the neighboring passage. As the flow with the cavitating passage arrives to the leading edge of the stator flow rate, it increases the incidence angle at the entrance to the stator, causing intermittent sheet and cloud cavitation on the stator blade.
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Hadavandi, Ruzbeh, Angelo Pasini, Dario Valentini, Giovanni Pace, and Luca d’Agostino. "Thermal Cavitation Instability Analysis in Axial Inducers by Means of Casing and Hub-Mounted Pressure Sensors." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5620.
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Abstract The effects of thermal cavitation on the flow instabilities developing in a three-bladed, tapered-hub, variable-pitch space turbopump inducer are described by illustrating the results of similarity experiments in water carried out at Sitael in the Cavitating Pump Rotordynamic Test Facility (CPRTF). The operating conditions have been varied as required for investigating the onset and response of the fluid dynamic instabilities occurring in the test inducer over a wide range of cavitation numbers from noncavitating to heavy cavitation conditions, both at design and off-design flow. The CPRTF water temperature has been varied from room conditions to 80 °C ca. in order to induce thermal cavitation effects of increasing intensity capable of reproducing in the experiments the occurrence of typical cavitation phenomena in cryogenic space propellants. A wide variety and number of axial and rotating fluid dynamic instabilities have been detected, identified and characterized by spectral analysis of the pressure measurements obtained from statoric and rotoric transducers flush-mounted on the casing and the hub of the test inducer. The results indicate that thermal cavitation significantly affects the types of flow instabilities developing in cavitating inducers and the range of flow and suction conditions for their occurrence.
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Cervone, Angelo, Cristina Bramanti, Emilio Rapposelli, and Luca d’Agostino. "Cavitation Experiments on Turbopump Inducers and Hydrofoils at Alta/Centrospazio: Overview and Future Activities." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77251.
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The aim of the present paper is to provide some highlights about the most interesting experimental activities carried out during the years 2000–2004 through the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Centrospazio/Alta S.p.A. After a brief description of the facility, the experimental activities carried out on a NACA 0015 hydrofoil for the characterization of the pressure coefficient on the suction side and evaluation the cavity length and oscillations are presented. Then, the results obtained to characterize the performance and the cavitation instabilities on three different axial inducers are showed: in particular, a commercial three-bladed inducer, the four-bladed inducer installed in the LOX turbopump of the Ariane Vulcain MK1 rocket engine and the “FAST2”, a two-bladed one manufactured by Avio S.p.A. using the criteria followed for the VINCI180 LOX inducer. The most interesting results are related to the effects of the temperature on the cavitation instabilities on hydrofoils and inducers. Experiments showed that some instabilities, like the cloud cavitation on hydrofoils and the surge on inducers, are strongly affected by the temperature, while others seem not to be influenced by the thermal effects. In the final part of this paper, some indications of the main experimental activities scheduled for the next future are provided.
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Watanabe, Masanobu, Koji Nishino, Yasumi Kitajima, Kazuyoshi Yonekura, and Tsuyoshi Hagiwara. "Flow-Induced Vibration of a Control Valve in a Cavitating Flow." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77373.
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The vibration response of a typical globe valve was measured to determine the characteristics of flow-induced vibration in a cavitating flow, varying valve opening rate from 20% to 40%, and flow rate from 0.2 m3/min to 1.4 m3/min or maximum flow rate of the test facility. Strain gauges were mounted on the valve shaft for these measurements. The upstream and downstream pressures of the globe valve were also measured to calculate the cavitation number or cavitation coefficient. Moreover, fluctuating pressures on the valve seat were measured simultaneously with strain signals to examine the correlation between the fluctuating fluid force and the vibration response. Cavitation occurred when the cavitation coefficient reached within the range from 0.42 to 0.47. On the other hand, the amplitude of the valve shaft in the drag direction increased drastically when the cavitation coefficient exceeded 0.8. The correlation between the fluctuating fluid force and the strain was investigated considering the sum of the measured pressures on the valve seat as fluctuating fluid force. A strong correlation between the fluctuating fluid force and the strain was obtained. The phase difference between fluctuating fluid force and the strain was about 40°. It was therefore concluded that the physical phenomenon was self-excited vibration coupled with a cavitating flow. This oscillation system is therefore considered as a negative damping system excited by the fluid force with time lag.
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Shukla, Shyam N., and Jagadish Kshirsagar. "Numerical Prediction of Cavitation in Model Pump." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66058.
Full textAbstract:
It is known that the pumps create suction and hence suck fluid. When a volume of liquid is subjected to a sufficiently low pressure, it may change its phase from liquid to gaseous resulting in vapor bubbles. The process of formation of vapour bubble in an area where the liquid pressure falls to the vapour pressure, and the subsequent collapse of those bubbles when they enter a region of higher pressure is referred to as cavitation. In pump industry, NPSH (net positive suction head) is the term frequently used to check cavitation condition. It is an absolute energy available above vapour pressure. A pump designer uses empirical relation to estimate cavitations performance of the impeller in absence of experimental test facility. One such correlation exists for optimizing the eye diameter of the pump. Based on the inlet flow velocity, rotational speed, the correlation brings out NPSHr value for different eye diameter. The trend shows that the NPSHr is higher with lower eye diameter; it continues to drop down with increasing eye diameter reaching lowest value and again increases gradually with further increase of eye diameter. An effort was made to give a scientific basis for the empirical correlation using Computational Fluid Dynamics approach. The present paper describes a case study wherein cavitation performance of the pump is predicted empirically. The pump is tested to check cavitation performance. These results are validated using commercially available CFD software for 3% head drop. Further to this, CFD code is used to check the variation of cavitation performance in respect to change of eye diameter. The paper in short presents three approaches, empirical, experimental and numerical simulation.
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Coutier-Delgosha, O., A. Dazin, G. Caignaert, and G. Bois. "Analysis of Cavitation Instabilities in a Four Blade Inducer." In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78406.
Full textAbstract:
The cavitating behavior of a four blade inducer tested in the LML laboratory large test facility is considered in the present paper. Experimental investigations based on unsteady pressure measurements and records from a six components balance mounted on the inducer shaft are performed. Spectral analysis of the signals enables to detect several characteristic frequencies related to unbalanced two-phase flow patterns. The objective of the present paper is the understanding of the physical phenomena associated to these frequencies. Therefore, wavelet decomposition, flow visualizations, and direct analysis of the high-frequency force, moment, and pressure signals are applied. Results at nominal flow rate only are considered. Not only classical unbalanced cavitation patterns, but also unexpected flow organizations are discussed.