Thematische Bibliographien / Cavitation in hydrodynamic machine

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Auswahl der wissenschaftlichen Literatur zum Thema „Cavitation in hydrodynamic machine“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 1. Februar 2022

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Zeitschriftenartikel zum Thema "Cavitation in hydrodynamic machine"

Zakrzewska, D. E., and A. K. Krella. "Cavitation Erosion Resistance Influence of Material Properties." Advances in Materials Science 19, no. 4 (2019): 18–34. http://dx.doi.org/10.2478/adms-2019-0019.

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AbstractThe cavitation erosion is the phenomena that causes degradation of fluid flow machinery components due to repetitive implosion of cavitation bubbles adjacent to the solid surface. Cavitation erosion is a complex phenomenon, which includes not only hydrodynamic factors of liquid, but also properties of erodible material e.g. microstructure, hardness or Young modulus. In order to reduce the negative impact of erosion on machine components, there are many methods to increase cavitation erosion resistance. The paper discusses the correlations between structural and mechanical properties and the resistance to cavitation erosion (CER) of pure materials, their alloys and coatings. Methods to increase CER have also been described - using heat / thermo-chemical treatment and application of coatings by various methods.

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Ghiban, Brandusa, Carmen Anca Safta, and Vlad Motoiu. "Stainless Steels as Erosion Resistant Materials for Hydraulic Machines." Key Engineering Materials 750 (August 2017): 75–79. http://dx.doi.org/10.4028/www.scientific.net/kem.750.75.

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The corrosion phenomena lead to serious modifications in the structure of metallic materials from which are manufactured the important active components of hydraulic machines. There are two important types of corrosion: cavitation and silt erosion (abrasive erosion), that are specific to machines which are producing energy [1, 2, 3]. As a corrosion mechanism, in hydrodynamic cavitation [4, 5], when cavitation bubbles implode on the solid surface of hydraulic machine component, the local pressure developed is high and can exceed the fatigue strength, yield point or compression strength of the material. Cavitation phenomenon can be produced in different ways. Four types of cavitation are described in the literature, looking for the method of producing, [6]: hydrodynamic cavitation, particle cavitation, acoustic cavitation, and optic cavitation. Abrasive erosion is the gradual degradation of a structure under the action of solid particles suspended in the working fluid. Impact and sliding erosion are the main categories of abrasive erosion approached in the literature by considering the mechanisms of which the abrasive particles act on the metallic surface, [2]. In the last decades the abrasive erosion phenomenon became a serious problem for the efficient operation of power plants, for instance in hydropower plants [7, 8]. Geothermal energy is the heat energy of the earth given by capturing the springs of heat water. In Romania the geothermal energy is used only for heating because the water has a low temperature and cannot be used to produce electric energy, only heat energy. So, although Romania is the third highest potential geothermal in Europe, practically electric energy from geothermal resource has a low thermal potential, [9]. A steam turbine is working at high rotational speed, high temperatures and using the working fluid which could be steam or wet steam. The working fluid is composed of corrosive chemicals with an aggressive pH. For this reason the common problems of the geothermal steam turbine failures are given by fractures of the blades (rotor blades or stator blades).

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Micu, Lavinia Madalina, Iosif Lazar, Adrian Circiumaru, Ilare Bordeasu, Liviu Daniel Pirvulescu, and mihai Hluscu. "New Results Regarding Cavitation Behavior of Polymers Modified with Anorganic Substances Coated on Bronze Surfaces." Materiale Plastice 55, no. 3 (2018): 460–63. http://dx.doi.org/10.37358/mp.18.3.5051.

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Due to mechanical resistance characteristics, chemical corrosion and abrasive erosion resistance, the polymers are more widely used in equipments and installations that are exploited in different fluid hydrodynamic conditions. Among these applications there is the protection of surfaces of hydromechanic organs stressed by cavitation, like in hydraulic machines rotors and valves. Consequently, the research aimes the extension of using these and protection of other components surfacess hardly streesed by cavitation. The research in this paper points toward the behavior of modified polymer layer, coated on surfaces of bronze used in casting the propellers of maritim and river ships. The tests were performed in standard piezoceramic crystal vibrating equipment within Cavitation Laboratory of Politehnica University of Timisoara. The damaging intensity of equipment is much greater than any cavitational vortex, created by ship propeller, hydraulic turbine or centrifugal pump. The obtained results, compared to both recorded on uncovered surfaces with polymer layer and recorded on surfaces covered with HVOF composite materials layers, show an increased resistance that implies the increased exploiting duration of those surfaces.

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Efremova, K. D., and V. N. Pilgunov. "Glycerin-containing Working Fluids for Hydraulic Drives for Special Purposes." Radio Engineering, no. 6 (December 26, 2020): 1–16. http://dx.doi.org/10.36027/rdeng.0620.0000182.

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The cavitation properties of a liquid must be taken into account in the engineering design of hydraulic machines and devices for hydraulic automation in cases when in their working process the absolute pressure in the liquid may drop below atmospheric, and the liquid is in a rarefied state for a certain time. Cold boiling, which occurs at a relatively low temperature and reduced absolute pressure inside or on the surface of the liquid, is considered as hydrostatic cavitation, if the liquid is stationary, or as hydrodynamic cavitation, if the liquid enters conditions under which the velocity head sharply increases in the flow section and the absolute pressure.In accordance with the theory of cavitation, the first phase of cavitation occurs when the absolute pressure in the degassed liquid drops to the value of the saturated vapor pressure and the air dissolved in the liquid, leaving the intermolecular space, turns into microbubbles of undissolved air and becomes a generator of cavitation "nuclei". Of practical interest is a quantitative assessment of the value of the minimum permissible absolute pressure in a real, partially or completely degassed liquid, at which hydrostatic cavitation occurs.Since the pressure of saturated vapor of a liquid is, to a certain extent, associated with the forces of intermolecular interaction, it is necessary to have information on the cavitation properties of technical solutions, including the solution of air in a liquid, since a solute can weaken intermolecular bonds and affect the value of the pressure of saturated vapors of the solvent. The article describes an experiment carried out by the authors to evacuate liquids. During the experiment, evacuation of various liquids was carried out using a developed hydraulic vacuum pump with a pneumatic drive.The article presents the technologies of hydrostatic and hydrodynamic degassing of liquids used in the experiment.As a result of experimental studies of the cavitation properties of pure glycerin and glycerin in the form of a 49/51% solution in water, mineral oil and aviation kerosene, quantitative estimates of the permissible absolute pressure in the considered technical fluids and solutions were obtained, its dependence on the saturated vapor pressure, the influence of the degree of hydrodynamic degassing the liquid, and the amount of dissolved substance in it on the strength of the liquid to rupture.In the process of studying the cavitation properties of solutions, it was found that the level of permissible absolute pressure in the solution is greater than that of the solvent. It has been suggested that dissolved solid, liquid or gaseous substances weaken the intermolecular bonds of the solvent and increase the pressure of its saturated vapor.On the basis of the experimental studies, a method for determining the highest rarefaction in solvents and in glycerol solutions has been developed. In addition, a comparative assessment of the cavitation properties of the considered technical fluids is given.

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Usman, Ali, and Cheol Woo Park. "Numerical optimization of surface texture for improved tribological performance of journal bearing at varying operating conditions." Industrial Lubrication and Tribology 70, no. 9 (2018): 1608–18. http://dx.doi.org/10.1108/ilt-10-2017-0286.

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Purpose Journal bearings are used in numerous rotary machines. The load carrying capacity and friction of a bearing have been major concerns in design. Recent developments in surface texturing have showed potential outcomes to improve the tribological characteristics of mating surfaces. This study aims to investigate surface textures, which are transverse to the sliding direction, for frictional response of the journal bearing. Design/methodology/approach A hydrodynamic lubrication model is considered to evaluate the effect of surface texturing on the performance of a journal bearing at varying operating conditions. The two-dimensional generalized Reynolds equation, coupled with mass-conserving Elrod cavitation algorithm, is solved to evaluate texture-induced variations in tribological performance parameters. Findings Results have showed remarkable improvements in frictional response. Moreover, micro-textures on the journal surface alter the cavitation response and film-reformation in the hydrodynamic conjunction of the plain bearing. Originality/value Operating condition-based comprehensive exhaustive optimization of texture geometry is performed to generate widespread conclusion.

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Zhang, Yu, Guoding Chen, and Lin Wang. "Effects of thermal and elastic deformations on lubricating properties of the textured journal bearing." Advances in Mechanical Engineering 11, no. 10 (2019): 168781401988379. http://dx.doi.org/10.1177/1687814019883790.

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Hydrodynamic journal bearing is an important part of rotary machine and faces many challenges such as high rotating speed, heavy specific pressure, and large temperature rise with the development of industry. These challenges lead to notable thermal and elastic deformations of the journal bearing. Surface texture has been proved to be a valid method to promote bearing lubricating properties. However, effects of thermal and elastic deformations on lubricating properties of the textured journal bearing have not been clearly analyzed. Based on this, the article presents a method to transform thermal–structural–fluid interaction into thermal–structural interaction and thermal–fluid interaction based on textured journal bearing model. Cavitation and temperature-viscosity effects are also considered. Based on this method, action mechanisms of surface texture on lubricating properties are discussed considering elastic and thermal deformations, and effects of elastic and thermal deformations on the textured journal bearing are also investigated. The results show that the load carrying capacity and the maximum oil film pressure of the textured journal bearing both increase when elastic and thermal deformations are considered. Optimal texture parameters can enhance the backflow effect in dimples and restraint cavitation phenomenon in the oil film rupture region. Meanwhile, inertial and cavitation effects caused by surface texture have significant effects on elastic and thermal deformations of the journal bearing.

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Ma, Chenbo, Yanjun Duan, Bo Yu, Jianjun Sun, and Qiaoan Tu. "The comprehensive effect of surface texture and roughness under hydrodynamic and mixed lubrication conditions." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 10 (2017): 1307–19. http://dx.doi.org/10.1177/1350650117693146.

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A theoretical study is carried out to investigate the comprehensive effect of the machined roughness and fabricated textures, by solving the average Reynolds equation coupled with a mass-conservative cavitation algorithm and taking into account asperity contact. We analyzed the influence of surface roughness, which is represented by the combined root-mean-square roughness σ and surface pattern parameter γ on the optimum texture parameters including the dimple depth-over-diameter ratio and area density under hydrodynamic and mixed lubrication conditions. The results show that the effect of surface roughness on load-carrying capacity can be ignored under hydrodynamic lubrication condition. Furthermore, the optimum texture parameters under hydrodynamic lubrication condition and the optimum dimple depth-over-diameter ratio under mixed lubrication condition are determined at minimized friction coefficient, which can be taken as the same for smooth-textured surface and rough-textured surface. The corresponding minimum friction coefficient increases with increasing σ and γ, and decreasing dimple area density under mixed lubrication condition.

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Hatakenaka, Kiyoshi, Masato Tanaka, and Kenji Suzuki. "A Theoretical Analysis of Floating Bush Journal Bearing With Axial Oil Film Rupture Being Considered." Journal of Tribology 124, no. 3 (2002): 494–505. http://dx.doi.org/10.1115/1.1454104.

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A new modified Reynolds equation is derived with centrifugal force acting on the hydrodynamic oil film being considered. This equation, together with a cavitation model, is used to obtain the steady-state equilibrium and calculate the rotordynamic coefficients of lightly loaded floating bush journal bearings operating at very high shaft speeds. The bush-to-shaft speed ratio and the linear cross-coupling spring coefficients of the inner oil film is found to decrease with the increase in shaft speed as the axial oil film rupture develops in the inner oil film. The present model can give reasonable explanation to the steady-state behavior and the stability behavior of the bearing observed in actual machines.

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Leighton, M., Nicholas Morris, Gareth Trimmer, Paul D. King, and Homer Rahnejat. "Efficiency of disengaged wet brake packs." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 6 (2018): 1562–69. http://dx.doi.org/10.1177/0954407018758567.

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Key objectives in off-highway vehicular powertrain development are fuel efficiency and environmental protection. As a result, palliative measures are made to reduce parasitic frictional losses while sustaining machine operational performance and reliability. A potential key contributor to the overall power loss is the rotation of disengaged wet multi-plate pack brake friction. Despite the numerous advantages of wet brake pack design, during high-speed manoeuvre in highway travel or at start-up conditions, significant frictional power losses occur. The addition of recessed grooves on the brake friction lining is used to dissipate heat during engagement. These complicate the prediction of performance of the system, particularly when disengaged. To characterise the losses produced by these components, a combined numerical and experimental approach is required. This paper presents a Reynolds-based numerical model including the effect of fluid inertia and squeeze film transience for prediction of performance of wet brake systems. Model predictions are compared with very detailed combined Navier–Stokes and Rayleigh-Plesset fluid dynamics analysis to ascertain its degree of conformity to representative physical operating conditions, as well the use of a developed experimental rig. The combined numerical and experimental approach is used to predict significant losses produced during various operating conditions. It is shown that cavitation becomes significant at low temperatures due to micro-hydrodynamic action, enhanced by high fluid viscosity. The magnitude of the losses for these components under various operating conditions is presented. The combined numerical-experimental study of wet multi-plate brakes of off-highway vehicles with cavitation flow dynamics has not hitherto been reported in the literature.

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Papulov, Vladimir. "BUILDING A THREE-DIMENSIONAL MODEL OF AXIAL JET IN SOLIDWORKS." Interexpo GEO-Siberia 7 (2019): 76–79. http://dx.doi.org/10.33764/2618-981x-2019-7-76-79.

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The article provides a brief description of the construction of the main parts of the three-dimensional model of the axial water jet, followed by their Assembly into the finished product. The role of computer simulation in the design of complex types of propellers, which include water jet, is shown. The possibility of solving problems of hydrodynamics with the help of "SolidWorks"is demonstrated. The design of the water jet pipe, taking into account the absence of cavitation. The urgency of application of three-dimensional modeling in the field of shipbuilding, using CAD-programs of machine-building orientation is shown.

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Dissertationen zum Thema "Cavitation in hydrodynamic machine"

Kadlec, Jan. "Hydraulický návrh induceru palivového čerpadla pro raketový motor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444265.

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The aim of this masters thesis is hydraulic design of inducer for given pump geometry and operating parameters. The first part of this thesis deals with cavitation problematic in hydrodynamic pumps. Next section describes two-dimensional design of the inducer and according to that, the 3D CAD model of inducer is made. The later part deals with thorough CFD analysis and determination of the main hydraulic parameters of inducer itself and also with whole pump completed with this inducer. The last section is devoted to inducer design improvement.

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Odeyemi, Babatunde O. "Hydrodynamic cavitation : effects of cavitation on inactivation of Escherichia coli (E.coli)." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/11009.

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Chanda, Suranjit Kumar. "Disintegration of sludge using ozone-hydrodynamic cavitation." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43105.

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In our study we applied hydrodynamic cavitation and ozonation both separately and combined, to determine the synergistic effect of these two technologies for sludge disintegration. A 2 mm orifice was used as a cavitation device. Ozone was injected after cavitation at a concentration of 35 mg/L at a flow of 3 Lpm. The sludge was subjected to treatment for 90 minutes in all three cases. In a final step, combined ozone and cavitation was applied to disintegrate the sludge for 10 hours. It was found that the combination of ozonation and cavitation exhibited higher sludge disintegration capacity than the individual technologies applied alone. About 31% of VSS was reduced by the combined system, whereas 19% was reduced by ozone and only 4% was reduced by cavitation alone after 90 minutes of treatment. Soluble chemical oxygen demand (SCOD) was increased by approximately 1600 mg/L in the combined system, which was much higher than the individual effect observed with either ozone or cavitation alone. About 75% of this SCOD was found to be biodegradable. In the combined system, soluble TOC increased by approximately 1.5 times the amount released by ozone alone, indicating higher release of organic matter from biomass. Only cavitation did not show any significant release of soluble total organic carbon (TOC) compared to the other treatments. In combined application, soluble biochemical oxygen demand (BOD) increased to 420 mg/L, which was significantly higher than the increase of BOD due to the application of ozone alone which was 260 mg/L. Based on the SCOD, it was found that a maximum of 50% of the sludge could be solubilised in 10 hours of combined treatment. It was also found that with ozone-cavitation, approximately 26% of the total sludge phosphorus was released to the solution after 10 hours, although most of the release occured within the first 2 hours. Within the operating conditions applied, cavitation itself was not sufficient for the disintegration of sludge, although better disintegration was found in combined application at higher inlet pressure. In the case of ozonation alone, higher disintegration was obtained at longer ozonation time.

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Skelton, Hedley John. "Applying hydrodynamic cavitation to the activated sludge process." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613352.

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Tran, David. "Hydrodynamic cavitation applied to food waste anaerobic digestion." Thesis, Linköpings universitet, Tema Miljöförändring, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-128268.

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Innovative pre-treatment methods applied to anaerobic digestion (AD) have developed to enhance the methane yields of food waste. This study investigates hydrodynamic cavitation, which induce disintegration of biomass through microbubble formations, impact on food waste solubilisation and methane production during following AD. Two different sub-streams of food waste (before and after the digestion) pre-treated by hydrodynamic cavitation were evaluated in lab scale for its potential for implementation in a full scale practise. First, the optimum condition for the hydrodynamic cavitation device was determined based on the solids and chemical changes in the food waste. The exposure time was referred to as the number of cycles that the sample was recirculated through the cavitation inducer’s region. The optimal cycles were later tested as a pre-treatment step in a BMP test and semi-CSTR lab scale operation. The tests showed that sufficient impact from the hydrodynamic cavitation was achieved by 20 cavitation cycles. Due to the pre-treatment, food waste solubilisation increased, up to 400% and 48% in terms of turbidity and sCOD measurements, respectively. In the BMP test, the treated samples improved the methane yield by 9-13%, where the digested food waste increased its kinetic constant by 60%. Fresh food waste was then processed in the semi-CSTR operation and the methane yield was increased by up to 17% with hydrodynamic cavitation for two reference periods. These promising results suggest that the hydrodynamic cavitation can be implemented for full scale production with food waste.

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Abrahamsson, Louise. "Improving methane production using hydrodynamic cavitation as pre-treatment." Thesis, Linköpings universitet, Tema Miljöförändring, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-128783.

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To develop anaerobic digestion (AD), innovative solutions to increase methane yields in existing AD processes are needed. In particular, the adoption of low energy pre-treatments to enhance biomass biodegradability is needed to provide efficient digestion processes increasing profitability. To obtain these features, hydrodynamic cavitation has been evaluated as an innovative solutions for AD of waste activated sludge (WAS), food waste (FW), macro algae and grass, in comparison with steam explosion (high energy pre-treatment). The effect of these two pre-treatments on the substrates, e.g. particle size distribution, soluble chemical oxygen demand (sCOD), biochemical methane potential (BMP) and biodegradability rate, have been evaluated. After two minutes of hydrodynamic cavitation (8 bar), the mean fine particle size decreased from 489- 1344 nm to 277- 381 nm (≤77% reduction) depending of the biomasses. Similar impacts were observed after ten minutes of steam explosion (210 °C, 30 bar) with a reduction in particle size between 40% and 70% for all the substrates treated. In terms of BMP value, hydrodynamic cavitation caused significant increment only within the A. nodosum showing a post treatment increment of 44% compared to the untreated value, while similar values were obtained before and after treatment within the other tested substrates. In contrast, steam explosion allowed an increment for all treated samples, A. nodosum (+86%), grass (14%) and S. latissima (4%). However, greater impacts where observed with hydrodynamic cavitation than steam explosion when comparing the kinetic constant K. Overall, hydrodynamic cavitation appeared an efficient pre-treatment for AD capable to compete with the traditional steam explosion in terms om kinetics and providing a more efficient energy balance (+14%) as well as methane yield for A. nodosum.<br>Det behövs innovativa lösningar för att utveckla anaerob rötning i syfte att öka metangasutbytet från biogassubstrat. Beroende på substratets egenskaper, kan förbehandling möjliggöra sönderdelning av bakterieflockar, uppbrytning av cellväggar, elimination av inhiberande ämnen och frigörelse av intracellulära organiska ämnen, som alla kan leda till en förbättring av den biologiska nedbrytningen i rötningen. För att uppnå detta har den lågenergikrävande förebehandlingsmetoden hydrodynamisk kavitation prövats på biologiskt slam, matavfall, makroalger respektive gräs, i jämförelse med ångexplosion. Effekten på substraten av dessa två förbehandlingar har uppmäts genom att undersöka distribution av partikelstorlek, löst organiskt kol (sCOD), biometan potential (BMP) och nedbrytningshastigheten. Efter 2 minuters hydrodynamisk kavitation (8 bar) minskade partikelstorleken från 489- 1344 nm till 277- 281 nm (≤77 % reduktion) för de olika biomassorna. Liknande påverkan observerades efter tio minuters ångexplosion (210 °C, 30 bar) med en partikelstorlekreducering mellan 40 och 70 % för alla behandlade substrat. Efter behandling med hydrodynamisk kavitation, i jämförelse med obehandlad biomassa, ökade metanproduktionens hastighetskonstant (K) för matavfall (+65%), makroalgen S. latissima (+3%), gräs (+16 %) samtidigt som den minskade för A. nodosum (-17 %). Förbehandlingen med ångexplosion ökade hastighetskonstanten för S. latissima (+50 %) och A. nodosum (+65 %) medan den minskade för gräs (-37 %), i jämförelse med obehandlad biomassa. Vad gäller BMP värden, orsakade hydrodynamisk kavitation små variationer där endast A. nodosum visade en ökning efter behandling (+44 %) i jämförelse med obehandlad biomassa. Biomassa förbehandlade med ångexplosion visade en ökning för A .nodosum (+86 %), gräs (14 %) och S. latissima (4 %). Sammantaget visar hydrodynamisk kavitation potential som en effektiv behandling före rötning och kapabel att konkurrera med den traditionella ångexplosionen gällande kinetik och energibalans (+14%) samt metanutbytet för A. nodosum.

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Ramirez, David A. "Improvement of Ethanol Production on Dry-Mill Process Using Hydrodynamic Cavitation Pretreatment." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354646654.

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Lunnbäck, Johan. "Hydrodynamic cavitation applied to anaerobic degradation of fats, oils and greases (FOGs)." Thesis, Linköpings universitet, Tema Miljöförändring, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-140685.

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To increase profitability for biogas production, new innovative substrates and condition of operations needs to be implemented. At the current state, fats, oils and greases (FOGs) represent a promising substrate even though it brings operational challenges to the anaerobic digestion process. By utilizing hydrodynamic cavitation (HC) as a pre-treatment of the FOGs, the efficiency of FOGs’ co-digestion with wastewater sludge can be significantly improved. Preliminary experiments conducted on oil and water demonstrates that the HC pre-treatment improves the oil solubilisation as well as forms stable oil and water emulsion that last for several hours. The pre-treatment also improved the soluble chemical oxygen demand (COD) of biosludge (BiSl) by up to 115% and the initial degradation rate by up to 35%. In a semi-continues system, this allowed a significant increment in the specific methane yield depending on the organic loading rate (OLR) applied1. With sufficient process optimization, the HC-pre-treatment may prove to be an energy efficient and effective pre-treatment of FOGs.

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Pamidi, Taraka Rama Krishna. "Process Intensification by Ultrasound Controlled Cavitation." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73856.

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Process industries are cornerstones in today’s industrialized society. They contribute significantly in the manufacturing of various goods and products that are used in our day-to-day life. Our society’s paradigm of consumerism accompanied by a rise in global population drives an ever increasing demand for goods. One of many strategies developed to satisfy these demands and at the same time improve production capabilities is known as process intensification. As an example, this can be accomplished by implementation of devices using the principle of hydrodynamic and acoustic cavitation. High-intensity cavitation in the ultrasonic range can change the physical and chemical properties of a wide range of substances and hence, improve the production rate or quality. Despite the generally accepted benefits of hydrodynamic and acoustic cavitation, applications in the process industry are yet limited. The reasons are that the method requires extensive optimization, which depends on multiple process parameters and encounters problem in the implementation on a larger scale. Scalable cavitation reactor concepts for industrial applications need to meet challenges like stability and robustness, energy efficiency and high flow rates. This thesis focuses on the methodology for the design and optimization of a flow through cavitation reactor. An ultrasound reactor concept has been developed and tested for two different applications: i) Fibrillation processes typical for paper and pulp industry; ii) Metal leaching of mineral concentrates. Simulations were carried out using a commercially available software for multiphysics modeling which combines acoustics, structural dynamics, fluid dynamics and piezoelectrics. However, the optimization procedure requires extensive experimental work in parallel with multi-physical simulations. In general, the application leads to hydrodynamic initiation of small gas bubbles in the fluid to be excited and collapsed by high-intensity ultrasound. This transient collapse of the cavitation bubbles provides both mechanical and chemical effect on materials. The developed reactor has a power conversion efficiency of 36% in batch mode and is well suited for a scale-up. In flow-through mode, the cavitation effect improves extensively and provides stable results. Energy efficiency requires hydrodynamic initiation of cavitation bubbles, high acoustic cavitation intensity by multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature with respect to the materials to be treated. The impact of flow conditions and hydrodynamic cavitation is significant and almost doubles the yield at the same ultrasonic power input. In the case of fibrillation of cellulose fibers, results obtained indicate that generated cavitation intensity changes the mechanical properties of the fiber wall. In the case of leaching, experiments show that six hours of exposure gave a 57% recovery of tungsten from the scheelite concentrate at 80°C and atmospheric pressure. Future research will focus on different types of excitation signals, extended reactor volume, increased flow rates and use of a higher process temperature.

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Bangaru, Balasundaram. "A detailed investigation of microbial cell disruption by hydrodynamic cavitation for selective product release." Doctoral thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/5345.

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Includes bibliographical references.<br>Hydrodynamic cavitation is a novel method for microbial cell disruption, mediated by intense pressure fluctuations caused by cavity oscillation and collapse. Selective release of intracellular microbial products is desirable to reduce the cost involved in their downstream processing. A study of the process variables that affect microbial cell disruption by hydrodynamic cavitation is presented in order to ascertain the conditions required for a selective release. Two model systems were considered (yeast and E. coil). Enzymes from different locations of the cell were studied and the release compared with other methods of disruption.

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Bücher zum Thema "Cavitation in hydrodynamic machine"

Hydraulics of pipelines: Pumps, valves, cavitation, transients. Wiley, 1989.

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Brewe, David E. Effect of vibration amplitude on vapor cavitation in journal bearings. National Aeronautics and Space Administration, 1987.

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Ranade, Vivek V. Hydrodynamic Cavitation: Devices, Design and Applications. Wiley & Sons, Limited, John, 2021.

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Ozonek, Janusz. Application of Hydrodynamic Cavitation in Environmental Engineering. Taylor & Francis Group, 2012.

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Ozonek, Janusz. Application of Hydrodynamic Cavitation in Environmental Engineering. Taylor & Francis Group, 2012.

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Application Of Hydrodynamic Cavitation In Environmental Engineering. CRC Press, 2012.

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Ozonek, Janusz. Application of Hydrodynamic Cavitation in Environmental Engineering. Taylor & Francis Group, 2012.

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Ozonek, Janusz. Application of Hydrodynamic Cavitation in Environmental Engineering. CRC Press, 2012. http://dx.doi.org/10.1201/b11825.

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Ozonek, Janusz. Application of Hydrodynamic Cavitation in Environmental Engineering. Taylor & Francis Group, 2012.

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Hydrodynamic Performance of the Large Cavitation Channel (LCC). Storming Media, 2002.

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Buchteile zum Thema "Cavitation in hydrodynamic machine"

Brujan, Emil-Alexandru. "Hydrodynamic Cavitation." In Cavitation in Non-Newtonian Fluids. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15343-3_4.

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Gogate, Parag R., and Aniruddha B. Pandit. "Cavitation Generation and Usage Without Ultrasound: Hydrodynamic Cavitation." In Theoretical and Experimental Sonochemistry Involving Inorganic Systems. Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-3887-6_3.

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Manuello, A., R. Malvano, O. Borla, A. Palumbo, and A. Carpinteri. "Neutron Emissions from Hydrodynamic Cavitation." In Fracture, Fatigue, Failure and Damage Evolution, Volume 8. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-21611-9_22.

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Bark, Göran, and Rickard E. Bensow. "Hydrodynamic Processes Controlling Cavitation Erosion." In Advanced Experimental and Numerical Techniques for Cavitation Erosion Prediction. Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-8539-6_8.

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Pandit, A. B. "Hydrodynamic Cavitation Technology: Industrial Applications." In The Mind of an Engineer. Springer Singapore, 2015. http://dx.doi.org/10.1007/978-981-10-0119-2_43.

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Desikan, Ramesh, Sivakumar Uthandi, and Kiruthika Thangavelu. "Pretreatment via Hydrodynamic Cavitation Process." In Methods in Molecular Biology. Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1323-8_2.

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Cervone, Angelo, Lucio Torre, Angelo Pasini, and Luca d’Agostino. "Cavitation and Turbopump Hydrodynamics Research at Alta S.P.A. and Pisa University." In Fluid Machinery and Fluid Mechanics. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89749-1_11.

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Gogate, Parag R. "Application of Hydrodynamic Cavitation for Food and Bioprocessing." In Food Engineering Series. Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7472-3_6.

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Mahanti, Naveen Kumar, Subir Kumar Chakraborty, S. Shiva Shankar, and Ajay Yadav. "Hydrodynamic Cavitation Technology for Food Processing and Preservation." In Emerging Thermal and Nonthermal Technologies in Food Processing. Apple Academic Press, 2020. http://dx.doi.org/10.1201/9780429297335-8.

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Ceccio, Steven L., and Simo A. Mäkiharju. "Experimental Methods for the Study of Hydrodynamic Cavitation." In Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-49719-8_2.

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Konferenzberichte zum Thema "Cavitation in hydrodynamic machine"

Mishra, Chandan, and Yoav Peles. "Hydrodynamic Cavitation in Flow Through Micro-Constriction Elements Entrenched in Rectangular Microchannels." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77406.

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Hydrodynamic cavitation, the explosive growth and catastrophic collapse of vapor bubbles, has immense impact on the design and performance of hydraulic machinery in the macro world. However, cavitation in high-speed microfluidic systems has received scarce attention and hardly been reported. This article reports the presence of hydrodynamic cavitation in the flow of de-ionized water through 11.5–40micron wide rectangular slot micro-orifices entrenched inside 100–200micron wide microchannels. Pioneering experimental investigations on hydrodynamic cavitation in rudimentary microfluidic configurations such as slot micro-orifices has been presented and unique cavitating flow patterns have been identified. Assorted cavitating (two-phase) flow patterns including incipient, choking and supercavitation have been detected. Designers of high-velocity microfluidic systems, especially Power-MEMS devices, need to be aware of the deleterious effects of cavitation as it can significantly affect device performance. The effects of micro-orifice and microchannel size on cavitation have been discussed and results indicate the existence of strong scale effects. Incipient and choking cavitation numbers are observed to increase with increasing micro-orifice size, while the orifice discharge coefficient plummets once cavitation activity erupts. In addition, inlet pressure effects on several cavitation parameters have been discussed and compared with established macro-scale results. The cavitating flow patterns encountered are significantly influenced by the micro-orifice and microchannel size. Flow rate choking occurs irrespective of the inlet pressures and is a direct consequence of cavitation inside the micro-orifice. Cavitation hysteresis is observed but its effects are more marked for the smallest micro-orifice.

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Pyun, Kwon Bum, Woo Chul Kwon, Kyoung Taek Oh, and Joon Yong Yoon. "Investigation of the Performance for a Heat Generator Using Hydrodynamic Cavitation." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-22045.

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Cavitation occurs typically when pressure is lower than the saturated vapor pressure. Generally, cavitation used to be a phenomenon engineer should avoid when they design fluid machinery because it creates erosion, vibration and noise that make performance of the machineries worse. Recently, study about generating energy with cavitaion is being proceeded like heat generating machinery which is the most typical. There is little academic research, although study about these has some commercial documents or patents. In this study, we proceed experimental study for the heat generator connected to electrical motor which generates heat from cavitaion using a fast rotating device. We used 15 kW and 55 kW electric motors to rotate the generator. The experiments performed changing flow conditions such as pressure at entering position by using a booster pump and rotating velocity of the motors by an inverter. We analyzed heat production and thermal efficiency according to the flow conditions. The front cover of the heater is made of acrylic plate so that we can use high speed photography to observe the relation between cavitation and generator shape. We made sure that these conditions can affect performance and especially pressure at entrance or rotating velocity affect heat production. Existing theory of cavitation and results of this study were discussed. These results could be useful for design process of the machine using cavitation such as a cavitation heat generator and a chemical reactor etc.

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Závorka, Dalibor, and Vladimír Habán. "Monitoring of hydraulic machines and hydrodynamic cavitation using acoustic emissions." In 37TH MEETING OF DEPARTMENTS OF FLUID MECHANICS AND THERMODYNAMICS. Author(s), 2018. http://dx.doi.org/10.1063/1.5049930.

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Skelley, Stephen. "Inducer Hydrodynamic Forces in a Cavitating Environment." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56115.

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Marshall Space Flight Center has developed and demonstrated a measurement device for sensing and resolving the hydrodynamic loads on fluid machinery. The device — a derivative of the six-component wind tunnel balance — senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This “rotating balance” was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining the amplitude and frequency content associated with operating in various cavitation modes. The rotating balance was calibrated statically using a dead-weight load system in order to generate the 6 × 12 calibration matrix later used to convert measured voltages to engineering units. Structural modeling suggested that the rotating assembly first bending mode would be significantly reduced with the balance’s inclusion. This reduction in structural stiffness was later confirmed experimentally with a hammer-impact test. This effect, coupled with the relatively large damping associated with the rotating balance waterproofing material, limited the device’s bandwidth to approximately 50 Hertz. Other pre-test validations included sensing the test article rotating assembly built-in imbalance for two configurations and directly measuring the assembly mass and buoyancy while submerged under water. Both tests matched predictions and confirmed the device’s sensitivity while stationary and rotating. The rotating balance was then demonstrated in a water test of a full-scale Space Shuttle Main Engine high-pressure liquid oxygen pump inducer. Experimental data was collected a scaled operating conditions at three flow coefficients across a range of cavitation numbers for the single inducer geometry and radial clearance. Two distinct cavitation modes were observed: symmetric tip vortex cavitation and alternate-blade cavitation. Although previous experimental tests on the same inducer demonstrated two additional cavitation modes at lower inlet pressures, these conditions proved unreachable with the rotating balance installed due to the intense dynamic environment. The sensed radial load was less influenced by flow coefficient than by cavitation number or cavitation mode although the flow coefficient range was relatively narrow. Transition from symmetric tip vortex to alternate-blade cavitation corresponded to changes in both radial load magnitude and radial load orientation relative to the inducer. Sensed moments indicated that the effective load center moved downstream during this change in cavitation mode. An occurrence of “higher-order cavitation” was also detected in both the stationary pressures and the rotating balance data although the frequency of the phenomena was well above the reliable bandwidth of the rotating balance. In summary the experimental tests proved both the concept and device’s capability despite the limitations and confirmed that hydrodynamically-induced forces and moments develop in response to the unbalanced pressure field, which is, in turn, a product of the cavitation environment.

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Peles, Yoav, and Chandan Mishra. "Cavitation in MicroElectroMechanical Systems (MEMS): Importance, Deviations From Conventional Scale, and Preliminary Results." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77405.

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Hydrodynamic cavitation in micro systems is a fundamental engineering problem that is poorly understood. The lack of knowledge on cavitation relevant to MEMS devices is impeding the practical realization of novel high-velocity microfluidic machines. This paper divulges differences between cavitation occurring inside micro and conventional systems, and also indicates the limited applicability of conventional knowledge to predict and understand cavitating flows in micro-domains. A detailed discussion delineating the possible reasons of such a divergence is presented in this article. Additionally, selected results obtained from preliminary experiments on cavitation in micro-domains are presented.

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Ge, Mingming, Guangjian Zhang, Navid Nematikourabbasloo, Kamel Fezzaa, and Olivier Coutier-Delgosha. "Application of Fast Synchrotron X-ray Imaging in Velocimetry of Cavitating Flows." In SNAME 26th Offshore Symposium. SNAME, 2021. http://dx.doi.org/10.5957/tos-2021-15.

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Hydrodynamic cavitation is a complex two-phase flow phenomenon involving mass and heat transfer between liquid and vapor. It occurs in many widely-used hydraulic machines, such as pumps and marine propellers, and often leads to undesired effects like material erosion, noise, and vibration. To control these detrimental effects, the visualization of two-phase flow morphology inside the opaque cavity is a crucial point to improve the physical and numerical models of cavitation. The major challenge in experimental measurements of cavitating flow fields is the fact that multiple scattering and a direct reflection of visible light from phase boundaries make the flow optically opaque. In recent years, unlike traditional local measurements using various probes, the development of the third-generation synchrotron radiation sources promotes the application of Xray phase-contrast imaging, which enables clear visualization of boundaries between phases with different refractive indices. In this study, the partial cavity is formed in a convergent-divergent (Venturi) channel with a small contraction ratio where the relatively stable cavitation regime can be sustained in a wide range of cavitation numbers. The experiment performed at Advanced Photon Source (APS) of Argonne uses the short high-flux X-ray pulses emitted from synchrotron sources to capture fast dynamic events and minimize motion blur. The internal two-phase structures and bubble development dynamics inside the quasi-stable sheet cavitation can be identified. Aside from the detailed illustration of two-phase morphology, X-ray phase-contrast images were also used to perform velocimetry by tracking either seeded particles or phase interfaces inside the opaque regions. Through appropriate postprocessing to the recorded X-ray images of cavitation, the time resolved velocity and void fraction fields are obtained simultaneously. These unprecedented experimental data will be further explored in understanding fluid mechanics underneath the cavity, estimating slip velocity between fluid-vapor interactions, and reconstructing pressure fields for compressible flows.

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Uhkoetter, Stephan, Stefan aus der Wiesche, Michael Kursch, and Christian Beck. "Development and Validation of a Three-Dimensional Multiphase Flow CFD Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68201.

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The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach including cavitation and air entrainment for high-speed turbo-machinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty type gas turbine journal bearings.

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Seto, Mae L., Rubens Campregher, Stefan Murphy, and Julio Militzer. "Prediction of Ship Acoustic Signature Due to Fluid Flow." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43343.

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The contribution of flow noise to the radiated acoustic signature of CFAV Quest is of interest. Quest is the research ship used by Defence R&D Canada as a quiet platform. It is difficult to identify the flow noise component in an acoustic ranging so there is interest in predicting the flow noise as a first step towards extracting it from range measurements. Below propulsor cavitation inception speeds, machinery-induced noise dominates. While flow noise does not usually dominate in the presence of machinery-induced noise or propulsor cavitation, it is unclear what fraction of the total noise power flow noise constitutes. A direct numerical simulation for a complex ship geometry was impractical so an alternative approach was sought. An immersed boundary method was used to model the presence of the ship in the flow domain. The unsteady flow field was calculated using a finite volume method over an unstructured Cartesian grid. The flow field around Quest in straight and level flight was calculated at Reynolds numbers between 1.8×108 and 4.3×108, corresponding to a full-scale speed range of 4 to 10 knots. Results from such flow field predictions become the hydrodynamic sources in the integrals of Lighthill’s acoustic analogy to predict the far-field acoustic signature from the flow past the hull. These far-field predictions consist of computing the propagation and radiation of the hydrodynamic sources. This assumes noise generation and its propagation are decoupled. Under certain circumstances, knowledge of the predicted flow component helps to extract it from a standard acoustic ranging.

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Kerr, Thomas, and Adolfo Delgado. "Novel Approach for Optical Characterization of Thrust Collar Lubricated Area: Experimental and Numerical Results." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15467.

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Abstract Thrust collars (TCs) are bearing elements used in geared machinery that transmit axial loads from one shaft to another. TCs are primarily used in integrally geared compressors (IGCs), but are also found in gearboxes and marine propulsion applications. TCs are hydrodynamic elements featuring a converging-diverging wedge to generate a pressure field that reacts axial loads. Accurate modeling requires knowledge of the film characteristics such as cavitation, turbulence, and air ingestion, all of which reduce load capacity. Current models in the literature do not include mass-conserving cavitation algorithms or turbulent flow. The following paper introduces a new test rig that optically characterizes the thin film region of a thrust collar. The test rig geometries, speeds, and loads match those typically seen in IGC applications. The test rig utilizes a transparent acrylic window in conjunction with a high-speed camera to obtain high-speed images of the oil film. Images are filtered and averaged to obtain areas of interest in the oil film. Cavitation and turbulence areas are captured for pinion speeds of 2.5, 5, and 7.5 krpm, and axial loads of 0.5, 1, and 1.5 kN. Cavitation occurs in the diverging (upper) region of the TC and appears at pinion speeds over 5,000 rpm, but does not change in shape after that speed. The cavitation is independent of applied load. Turbulence at the inlet region (bottom) occurs at all speeds, but increases to almost 35% of the total area at the highest speed. This paper also presents a finite element (FE) model that includes predictions for the static characteristics of the TC, specifically the cavitation area. The cavitation modeling uses an iterative Elord’s method, which conserves mass. The model predicts a similar cavitation area for all speeds and loads. A computation fluid dynamics (CFD) study predicts a similar cavitation area, and pressure field to the FE model. The CFD model predicts turbulence in the lower region that increases for increasing spin speed, which matches the experimental results. The CFD model tends to underpredict the turbulence area when compared to the experiments. As IGCs move into novel application areas to satisfy new needs, the increase in efficiency and capacity comes at a cost of more load and higher speed requirements on the TCs. This work will help original equipment manufacturers model TCs more accurately to ensure safe and efficient operation.

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Terence Stoop, A. H., T. W. Bakker, H. J. M. Kramer, and G. J. Witkamp. "Hydrodynamic Cavitation at Elevated Backpressure." In 8th International Symposium on Cavitation. Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2826-7_203.

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Berichte der Organisationen zum Thema "Cavitation in hydrodynamic machine"

Park, Joel T., J. M. Cutbirth, and Wesley H. Brewer. Hydrodynamic Performance of the Large Cavitation Channel (LCC). Defense Technical Information Center, 2002. http://dx.doi.org/10.21236/ada416700.

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Thomas, Catherine, Afrachanna Butler, Victor Medina, Chris Griggs, and Alan Katzenmeyer. Physicochemical treatment of cyanobacteria and microcystin by hydrodynamic cavitation and advanced oxidation. Engineer Research and Development Center (U.S.), 2019. http://dx.doi.org/10.21079/11681/32313.

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