Relevant bibliographies by topics / Cavitation nozzle

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Cavitation nozzle'

Author: Grafiati
Published: 28 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Cavitation nozzle"

1

Wang, Xin Hua, Zhi Jie Li, Shu Wen Sun, and Gang Zheng. "Research on the Influence Factors of Cavitating Jet in Jet Pipe Amplifier Nozzle." Applied Mechanics and Materials 229-231 (November 2012): 617–20. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.617.

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The cavitation flow characteristics in jet pipe amplifier with different nozzles were simulated using commercial computational fluid dynamics (CFD) software. The influence of operating parameters and structural parameters of jet nozzles on cavitation jets are the key objective. These parameters mainly include inlet pressure, outlet pressure, temperature of water, nozzle convergence angle, the length of the nozzle cylindrical section, nozzle diameter and nozzle export chamfer angle. The results provide methods to limit the emergence and development of the nozzle jet internal cavitations.
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YANG, Yongfei, Wei LI, Weidong SHI, Chuan WANG, and Wenquan ZHANG. "Experimental Study on Submerged High-Pressure Jet and Parameter Optimization for Cavitation Peening." Mechanics 26, no. 4 (September 15, 2020): 346–53. http://dx.doi.org/10.5755/j01.mech.26.4.27560.

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To increase the performance of high pressure submerged cavitation jet that has been used for cavitation peening, the effect of stand-off distance and the nozzle geometry on the impact capacity is investigated and optimized. High speed photography of the cavitation bubble clouds taken to reveal the unsteady characteristics of the cavitating jet. The impact ability of the jet with different nozzles and standoff distance is tested using Al 1060 at first, and the optimized jet is used then for cavitation peening on 304 stainless steel. The surface profile as well as the grain structures before and after peening using different nozzles are observed from SEM images. It is found that, the divergent angle of the nozzle has a great effect on the impact capability of the submerged high-pressure jet, which is important for improving the peening efficiency. In the nozzles with divergent angle 40°, 60° and 80°, the 60° nozzle shows the best performance. After peening, grain cells under the metal surface are changed and a twin layer is formed. The current research reveals the transient characteristics of the submerged cavitation jet and main factors that affect its impact rate, which provides guide for the nozzle design and application for the high-pressure cavitation jet peening.
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Yang, Yongfei, Wei Li, Weidong Shi, Ling Zhou, and Wenquan Zhang. "Experimental Study on the Unsteady Characteristics and the Impact Performance of a High-Pressure Submerged Cavitation Jet." Shock and Vibration 2020 (June 16, 2020): 1–15. http://dx.doi.org/10.1155/2020/1701843.

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High-pressure submerged cavitation jet is widely used in the fields of material peening, petroleum drilling, and ocean engineering. The impact performance of the jet with intensive cavitation is related to the factors such as working condition and the nozzle geometry. To reveal the relationship between the nozzle divergent angle and the jet pressure on the unsteady characteristics of the jet, high-speed photography with frame rate of 20000 fps is used to record the image of the cavitation clouds. Grayscale analysis algorithm developed in MATLAB is used to study the effects of injecting condition on the special structure, unsteady characteristics, and shedding frequency of the cavitation bubbles. The impact load characteristics of the cavitation jet with different cavitation numbers and stand-off distances are recorded using a high-response pressure transducer. It is found that the cavitation number is the main factor affecting the cavitation morphology of the submerged jet. The lower the cavitation number is, the more intense the cavitation occurs. The outlet divergent angle of the convergent-divergent nozzle also has a significant influence on the development of the cavitation clouds. In the three nozzles with the outlet divergent angles of 40°, 80°, and 120°, the highest bubble concentration is formed usinga nozzle with a divergent angle of 40°, but the high-concentration cavitating bubbles are only distributed in a very small range of the nozzle outlet. The cavities generated by using the nozzle with a divergent angle of 80° can achieve good results in terms of concentration and distribution range, while the nozzle with divergent angle of 120° has lower cavitation performance due to the lack of the constraint at the outlet which intensifies the shear stress of the jet. According to the result of frame difference method (FDM) analysis, the jet cavitation is mainly formed in the vortex structure generated by the shearing layer at the nozzle exit, and the most severe region in the collapse stage is the rear end of the downstream segment after the bubble cloud sheds off. The impact load of the cavitation jet is mainly affected by the stand-off distance of the nozzle from the impinged target, while the nozzle outlet geometry also has an effect on the impact performance. Optimizing the stand-off distance and the outlet geometry of the nozzles is found to be a good way to improve the performance of the cavitation jet.
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Zhang, Feng Hua, Hai Feng Liu, Jun Chao Xu, and Chuan Lin Tang. "Experimental Investigation on Cavitation Noise of Water Jet and its Chaotic Behaviour." Applied Mechanics and Materials 121-126 (October 2011): 3919–24. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3919.

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The cavitation noise signals were collected separately for the cavitation nozzle and general nozzle at the target position and the nozzle exit in the condition of different standoff distance. The features of signal’s frequency spectrum and power spectrum were analyzed for different nozzles. Based on chaotic theory, phase space reconstruction was processed and the maximum Lyapunov exponent was calculated separately for each cavitation signal’s time series. Under the condition of this experiment, the difference between the general nozzle and cavitation nozzle was mostly marked at the target position while the standoff distance is 35 mm, which mainly displayed at the high frequency segment. The maximum Lyapunov exponent calculated appeared at standoff distance 35 mm. At the nozzle exit, the noise signal of cavitation nozzle is different from the general nozzle. The difference also displayed at the high frequency segment, and no changing with the standoff distance
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GIANNADAKIS, E., M. GAVAISES, and C. ARCOUMANIS. "Modelling of cavitation in diesel injector nozzles." Journal of Fluid Mechanics 616 (December 10, 2008): 153–93. http://dx.doi.org/10.1017/s0022112008003777.

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A computational fluid dynamics cavitation model based on the Eulerian–Lagrangian approach and suitable for hole-type diesel injector nozzles is presented and discussed. The model accounts for a number of primary physical processes pertinent to cavitation bubbles, which are integrated into the stochastic framework of the model. Its predictive capability has been assessed through comparison of the calculated onset and development of cavitation inside diesel nozzle holes against experimental data obtained in real-size and enlarged models of single- and multi-hole nozzles. For the real-size nozzle geometry, high-speed cavitation images obtained under realistic injection pressures are compared against model predictions, whereas for the large-scale nozzle, validation data include images from a charge-coupled device (CCD) camera, computed tomography (CT) measurements of the liquid volume fraction and laser Doppler velocimetry (LDV) measurements of the liquid mean and root mean square (r.m.s.) velocities at different cavitation numbers (CN) and two needle lifts, corresponding to different cavitation regimes inside the injection hole. Overall, and on the basis of this validation exercise, it can be argued that cavitation modelling has reached a stage of maturity, where it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions.
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Ishak, M. H. H., Farzad Ismail, Sharzali Che Mat, M. Z. Abdullah, M. S. Abdul Aziz, and M. Y. Idroas. "Numerical Analysis of Nozzle Flow and Spray Characteristics from Different Nozzles Using Diesel and Biofuel Blends." Energies 12, no. 2 (January 17, 2019): 281. http://dx.doi.org/10.3390/en12020281.

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In this paper, the discrete phase model (DPM) was introduced to study the fuel injector cavitations process and the macro spray characteristic of three different types of nozzle spray shape with diesel and hybrid biofuel blend for several injection pressures and backpressures. The three types of nozzle spray shapes used were circle, elliptical A type, and elliptical B type. The cavitations’ flows inside the injector nozzles were simulated with Computer Fluid Dynamics (CFD) simulations using the cavitations mixture approach. The effect of nozzle spray shape towards the spray characteristic of hybrid biofuel blends is analyzed and compared with the standard diesel. Furthermore, a verification and validation from both the experimental results and numerical results are also presented. The nozzle flow simulation results indicated that the fuel type did not affect the cavitation area vastly, but were more dependent on the nozzle spray shape. In addition, the spray width of the elliptical nozzle shape was higher as compared to the circular spray. Moreover, as the backpressure increased, the spray width downstream increased as well. The spray tip penetration for the elliptical nozzle shape was shorter than the circular nozzle shape due to circular nozzles having smaller nozzle widths and lesser spray cone angles. Thus, this resulted in smaller aerodynamic drag.
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Soyama, Hitoshi. "Cavitating Jet: A Review." Applied Sciences 10, no. 20 (October 17, 2020): 7280. http://dx.doi.org/10.3390/app10207280.

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When a high-speed water jet is injected into water through a nozzle, cavitation is generated in the nozzle and/or shear layer around the jet. A jet with cavitation is called a “cavitating jet”. When the cavitating jet is injected into a surface, cavitation is collapsed, producing impacts. Although cavitation impacts are harmful to hydraulic machinery, impacts produced by cavitating jets are utilized for cleaning, drilling and cavitation peening, which is a mechanical surface treatment to improve the fatigue strength of metallic materials in the same way as shot peening. When a cavitating jet is optimized, the peening intensity of the cavitating jet is larger than that of water jet peening, in which water column impacts are used. In order to optimize the cavitating jet, an understanding of the instabilities of the cavitating jet is required. In the present review, the unsteady behavior of vortex cavitation is visualized, and key parameters such as injection pressure, cavitation number and sound velocity in cavitating flow field are discussed, then the estimation methods of the aggressive intensity of the jet are summarized.
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Yang, Han, Yu Yong Lei, Huan Tao, Li Zhang, and Xuan Chen. "Simulation Study on Oscillating Cavitation Nozzle for Cleaning Based on FLUENT." Advanced Materials Research 997 (August 2014): 684–87. http://dx.doi.org/10.4028/www.scientific.net/amr.997.684.

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Abstract: Based on the basic theory of fluid dynamics and Fluent software, numeric simulation of self-excited oscillating cavitation jet nozzle for cleaning was carried out. The flow field characteristics within tubular organ cavitation nozzle is studied. By numerical simulation, the exit velocity, velocity vector distribution, pressure inside the nozzle as well as static pressure distribution were obtained. The simulation results show that there is a maximum speed at cylindric section inside the cavitation nozzle. When water jet getting into the cylindric section of the cavitation nozzle, there is a significant zone with high negative pressure.Also there is a obvious zone with negative pressure at the outlet end. When the pressure is below the saturation vapor pressure of the liquid, cavitation bubbles occured. Therefore the cavitating water jet was generated. The simulation results also show that there is a higher negative pressure inside the nozzle region when the nozzle inlet diameter Ds = 6 mm, the diameter of the cavity D = 3 mm, the diameter of the cylindric section d = 1.8mm, the resonator length L = 6.2 mm, spread angleα= 60 °, the length of the cylindric segment s = 6 mm, Thererfore it is beneficial effect for the cavitation generating.
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Wo, Heng Zhou, Ya Fang Zhang, Xian Guo Hu, and Yu Fu Xu. "Effect of Hardness of Needle-Sealing Surface of Pintle Nozzle on Cavitation Erosion." Applied Mechanics and Materials 130-134 (October 2011): 946–49. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.946.

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Nozzle is one of key parts in the diesel engine. The cavitation erosion of needle-sealing surface in the pintle nozzle has important influence on the fuel atomization, combustion and power performance of diesel engine. In order to investigate the effect of hardness of needle-sealing surface on cavitation erosion, two kinds of nozzles were selected and operated in S195 diesel engine for 10 hours. One nozzle is heat-treated one which has lower surface hardness; the other with higher surface hardness is real commercial nozzle. The surface appearances of original and operated nozzle-sealing surface were observed by SEM. It was found that the cavitation erosion on the seal surface of nozzle with lower hardness was severer than that of nozzle with higher hardness. However, their wear ways and formations are similar.
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ANDRIOTIS, A., M. GAVAISES, and C. ARCOUMANIS. "Vortex flow and cavitation in diesel injector nozzles." Journal of Fluid Mechanics 610 (August 8, 2008): 195–215. http://dx.doi.org/10.1017/s0022112008002668.

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Flow visualization as well as three-dimensional cavitating flow simulations have been employed for characterizing the formation of cavitation inside transparent replicas of fuel injector valves used in low-speed two-stroke diesel engines. The designs tested have incorporated five-hole nozzles with cylindrical as well as tapered holes operating at different fixed needle lift positions. High-speed images have revealed the formation of an unsteady vapour structure upstream of the injection holes inside the nozzle volume, which is referred to as ‘string-cavitation’. Computation of the flow distribution and combination with three-dimensional reconstruction of the location of the strings inside the nozzle volume has revealed that strings are found at the core of recirculation zones; they originate either from pre-existing cavitation sites forming at sharp corners inside the nozzle where the pressure falls below the vapour pressure of the flowing liquid, or even from suction of outside air downstream of the hole exit. Processing of the acquired images has allowed estimation of the mean location and probability of appearance of the cavitating strings in the three-dimensional space as a function of needle lift, cavitation and Reynolds number. The frequency of appearance of the strings has been correlated with the Strouhal number of the vortices developing inside the sac volume; the latter has been found to be a function of needle lift and hole shape. The presence of strings has significantly affected the flow conditions at the nozzle exit, influencing the injected spray. The cavitation structures formed inside the injection holes are significantly altered by the presence of cavitation strings and are jointly responsible for up to 10% variation in the instantaneous fuel injection quantity. Extrapolation using model predictions for real-size injectors operating at realistic injection pressures indicates that cavitation strings are expected to appear within the time scales of typical injection events, implying significant hole-to-hole and cycle-to-cycle variations during the corresponding spray development.
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Dissertations / Theses on the topic "Cavitation nozzle"

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Ahmed, Zayed. "Quantitative flow measurement and visualization of cavitation initiation and cavitating flows in a converging-diverging nozzle." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35522.

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Master of Science
Department of Mechanical and Nuclear Engineering
B. Terry Beck
Mohammad H. Hosni
Cavitation is the formation of vapor phase from the liquid phase by reduction in its absolute pressure below the saturation pressure. Unlike boiling, where the temperature of the liquid is increased to cause vaporization, the reduction in the pressure alone can cause the liquid to turn into vapor. Cavitation is undesirable in many engineering applications as it is associated with reduction in efficiency and is known to cause damage to pump and propeller components. However, the endothermic nature of cavitation could be utilized to create a region of low temperature that could be utilized to develop a new refrigeration cycle. The work presented in this thesis is part of ongoing research into the potential cooling capacity of cavitation phenomena, where the cavitation in a converging-diverging nozzle is being investigated. Due to the constricting nature of the throat of the converging-diverging nozzle, the liquid velocity at the throat is increased, obeying the continuity law. With an increase in velocity, a reduction in absolute pressure is accompanied at the throat of the nozzle according to the Bernoulli’s principle. The local absolute pressure at the throat can go lower than the saturation vapor pressure, thereby causing the fluid to cavitate. The effect of water temperature on the flowrates, the onset of cavitation within the nozzle, and the resulting length of the cavitation region within the nozzle are the subject of this thesis. Experimental results and analysis are presented which also show that near the onset of cavitation, the flowrate can go beyond the choked flowrate, causing the local pressure in the throat to go well below zero for an extended amount of time in the metastable state, before nucleating (cavitating) into a stable state. Flow visualization using a high speed digital camera under different operating conditions was aimed at investigating the region of cavitation onset, which appears to be associated with boundary layer separation just downstream of the nozzle throat. In order to delay the boundary layer separation point in the downstream section of the nozzle, the diffuser region of the nozzle was modified to enable two flow paths, where one path would suck the flow near the inner walls of the nozzle and the other would allow the bulk of the flow to pass through. This was achieved with the use of inserts. Various inserts were tested in an attempt to capture the effect of inserts on the cavitation phenomena. Their effect on the flowrates, length of two phase region, and cavitation onset are presented in this thesis.
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Rovder, Juraj. "Zkoušky kavitační eroze kavitujícím paprskem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444638.

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This thesis deals with the issue of cavitation and its effects. In this context, it describes the mechanism of origin and implosion of cavities and cavitation regimes. It lists various types of hydrodynamic cavitation. It presents the Rayleight-Plesset equation and describes micro jet. It also highlights cavitation erosion and the effects of cavitation on some types of materials. It deals with three types of cavitation resistance testing, namely cavitation tunnels, a vibrating cavitation system, supported by the ASTM G32 standard, and last but not least, cavitation nozzles, which follow the ASTM G134-17 standard. In correlation with cavitation nozzles, it frames its four basic parameters, which are stand of distance, the cavitation number, the speed of sound and the geometry of the nozzle. At the end of the theoretical part it characterizes the construction of test bench. The practical part is focused on performing the experiment. It first presents the procedure for carrying out the experiment and then evaluates this experiment. Part of the evaluation is the visual observation of selected samples of AlCu4Mg1Mn1 material and the monitoring of cavitation erosion on specific samples. First, these data are processed in the form of graphs and tables. It uses a microscope as a tool for detailed observation of samples. The conclusion of the practical part is devoted to the evaluation of the experiment.
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Schmidt, Aaron James. "Quantitative measurement and flow visualization of water cavitation in a converging-diverging nozzle." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32587.

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Master of Science
Department of Mechanical and Nuclear Engineering
B. Terry Beck
Mohammad H. Hosni
Cavitation is the change of a liquid to a two-phase mixture of liquid and vapor, similar to boiling. However, boiling generates a vapor by increasing the liquid temperature while cavitation generates vapor through a decrease in pressure. Both processes are endothermic, removing heat from the surroundings. Both the phase change and heat absorption associated with cavitation provide many engineering applications, including contributing to a new type of refrigeration cycle under development. Cavitation can occur at or below the vapor pressure; conditions that delay cavitation and allow for a metastable liquid are not well understood. A converging-diverging nozzle was designed and fabricated to create a low pressure region at the nozzle throat. The converging section of the nozzle increased the water velocity and decreased the pressure, according to Bernoulli’s principle. A cavitation front was formed slightly past the nozzle throat. The cavitation location suggested that the water was metastable near the nozzle throat. Flow through the system was controlled by changing the nozzle inlet and outlet pressures. The flowrate of water was measured while the outlet pressure was lowered. The flowrate increased as the outlet pressure dropped until cavitation occurred. Once cavitation initiated, the flow became choked and remained constant and independent of the nozzle outlet pressure. High-speed imagery was used to visualize the flow throughout the nozzle and the formation and collapse of cavitation in the nozzle’s diverging section. High-speed video taken from 1,000 to 35,000 frames per second captured the formation of the cavitation front and revealed regions of recirculating flow near the nozzle wall in the diverging section. Particle Image Velocimetry (PIV) was used to measure the velocity vector field throughout the nozzle to characterize flow patterns within the nozzle. PIV showed that the velocity profile in the converging section and throat region were nearly uniform at each axial position in the nozzle. In the diverging section, PIV showed a transient, high-velocity central jet surrounded by large areas of recirculation and eddy formation. The single-phase experimental results, prior to cavitation onset, were supplemented by Computational Fluid Dynamics (CFD) simulations of the velocity distribution using Fluent software.
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Wright, Michael Marshall. "Cavitation of a Water Jet in Water." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3175.

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Cavitation is a phenomenon that occurs in liquids when the pressure drops below the vapor pressure of the liquid. Previous research has verified that cavitation bubble collapse is a dynamic and destructive process. An understanding of the behavior of cavitation is necessary to implement this destructive mechanism from an axisymmetric jet for underwater material removal. This work investigates the influence of jet pressure and nozzle diameter on the behavior of a cloud of cavitation bubbles generated by a submerged high-pressure water jet. First, this investigation is put into context with a condensed historical background of cavitation research. Second, a description of the cavitation-generating apparatus is given. Next, the experimental methods used to explore the behavior of the cavitation clouds are explained. Finally, the results of the investigation, including propagation distance, cloud width and area, pulsation frequency, and cloud front velocity are presented. Among the results is a discussion of the significant experimental factors affecting the behavior of the cavitation clouds. It is shown that the Reynolds number, specifically the diameter of the nozzle, has a significant effect on the measurements. In some cases the jet pressure, and subsequent jet velocity, had a less significant effect than was expected. Overall, this research describes the cavitation cloud formed when a submerged high-speed water jet discharges.
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Patouna, Stavroula. "A CFD STUDY OF CAVITATION IN REAL SIZE DIESEL INJECTORS." Doctoral thesis, Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/14723.

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In Diesel engines, the internal flow characteristics in the fuel injection nozzles, such as the turbulence level and distribution, the cavitation pattern and the velocity profile affect significantly the air-fuel mixture in the spray and subsequently the combustion process. Since the possibility to observe experimentally and measure the flow inside real size Diesel injectors is very limited, Computational Fluid Dynamics (CFD) calculations are generally used to obtain the relevant information. The work presented within this thesis is focused on the study of cavitation in real size automotive injectors by using a commercial CFD code. It is divided in three major phases, each corresponding to a different complementary objective. The first objective of the current work is to assess the ability of the cavitation model included in the CFD code to predict cavitating flow conditions. For this, the model is validated for an injector-like study case defined in the literature, and for which experimental data is available in different operating conditions, before and after the start of cavitation. Preliminary studies are performed to analyze the effects on the solution obtained of various numerical parameters of the cavitation model itself and of the solver, and to determine the adequate setup of the model. It may be concluded that overall the cavitation model is able to predict the onset and development of cavitation accurately. Indeed, there is satisfactory agreement between the experimental data of injection rate and choked flow conditions and the corresponding numerical solution.This study serves as the basis for the physical and numerical understanding of the problem. Next, using the model configuration obtained from the previous study, unsteady flow calculations are performed for real-size single and multi-hole sac type Diesel injectors, each one with two types of nozzles, tapered and cylindrical. The objective is to validate the model with real automotive cases and to ununderstand in what way some physical factors, such as geometry, operating conditions and needle position affect the inception of cavitation and its development in the nozzle holes. These calculations are made at full needle lift and for various values of injection pressure and back-pressure. The results obtained for injection rate, momentum flux and effective injection velocity at the exit of the nozzles are compared with available CMT-Motores Térmicos in-house experimental data. Also, the cavitation pattern inside the nozzle and its effect on the internal nozzle flow is analyzed. The model predicts with reasonable accuracy the effects of geometry and operating conditions.
Patouna, S. (2012). A CFD STUDY OF CAVITATION IN REAL SIZE DIESEL INJECTORS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14723
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Reid, Benjamin A. "An optical investigation of cavitation phenomena in true-scale high-pressure diesel fuel injector nozzles." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6358.

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Efforts to improve diesel fuel sprays have led to a significant increase in fuel injection pressures and a reduction in nozzle-hole diameters. Under these conditions, the likelihood for the internal nozzle flow to cavitate is increased, which potentially affects spray breakup and atomisation, but also increases the risk of causing cavitation damage to the injector. This thesis describes the study of cavitating flow phenomena in various single and multi-hole optical nozzle geometries. It includes the design and development of a high-pressure optical fuel injector test facility with which the cavitating flows were observed. Experiments were undertaken using real-scale optical diesel injector nozzles at fuel injection pressures up to 2050 bar, observing for the first time the characteristics of the internal nozzle-flow under realistic fuel injection conditions. High-speed video and high resolution photography, using laser illumination sources, were used to capture the cavitating flow in the nozzle-holes and sac volume of the optical nozzles, which contained holes ranging in size from 110 micrometers to 300 micrometers. Geometric cavitation in the nozzle-holes and string cavitation formation in the nozzle-holes and sac volume were both observed using transient and steady-state injection conditions; injecting into gaseous and liquid back pressures up to 150 bar. Results obtained have shown that cavitation strings observed at realistic fuel injection pressures exhibit the same physical characteristics as those observed at lower pressures. The formation of string cavitation was observed in the 300 micrometers multi-hole nozzle geometries, exhibiting a mutual dependence on nozzle flow-rate and the geometry of the nozzle-holes. Pressure changes, caused by localised turbulent perturbations in the sac volume and transient fuel injection characteristics, independently affected the geometric and string cavitation formation in each of the holes. String cavitation formation of was shown to occur when free-stream vapour was entrained into the low pressure core of a sufficiently intense coherent vortex. Hole diameters less than or equal to 160 micrometers were found to suppress string cavitation formation, with this effect a result of the reduced nozzle flow rate and vortex intensity. Using different hole spacing geometries, it was demonstrated that the formation of cavitation strings in a particular geometry became independent of fuel injection and back pressure once a threshold pressure drop across the nozzle had been reached.
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Asher, William. "Fluid dynamics of cavitating sonic two-phase flow in a converging-diverging nozzle." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/17621.

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Master of Science
Department of Mechanical and Nuclear Engineering
Steven Eckels
Both cavitating and flashing flows are important phenomena in fluid flow. Cavitating flow, a common consideration in valves, orifices, and metering devices, is also a concern in loss of coolant accidents for liquid water in power plants when saturation pressures are below atmospheric pressure. Flashing flow is a common consideration for devices such as relief and expansion valves and fluid injectors as well as for loss of coolant accidents in which the coolant’s saturation pressure is above atmospheric. Of the two phenomena, flashing flow has received greater interest due to its applicability to safety concerns, though cavitating flow is perhaps of greater interest in terms of energy efficiency. It is possible for cavitating and flashing flow to actually become sonic. That is, the local velocity of a fluid can exceed the local speed of sound due to the unique properties of two-phase mixtures. When a flow becomes sonic, it is possible for the flow to accelerate and impose additional energy losses that would not otherwise occur. Models of this aspect of two-phase flow are not well developed, typically only being presented for the case of constant area ducts. In this paper two models for cavitating sonic flow are developed and described by applying the integral forms of the mass, momentum, and energy equations to a control volume of variable cross-sectional area. These models, based on the homogeneous equilibrium model (HEM) and separated flow model, are then applied to experimental data taken by the author with R-134a as the fluid of interest. Experimental data were taken with four instrumented converging-diverging nozzles of various geometries using a custom testing rig that allowed for precise control and measurement of flow parameters such as mass flow, temperature, and pressure. The resultant data from the models are then examined, focusing on the resultant velocities, Mach numbers, quality, and shear stresses.
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Hlaváček, David. "Kavitující proudění v konvergentně-divergentní trysce." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230045.

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The master´s thesis deals with the flow induced by rotation of cavitating fluid in converging-diverging nozzle, which simulates the vortex rope in impeller of water turbines. Measurement is performed on an experimental circuit in laboratory. Results from experimental measurements are compared with CFD simulation of single and two-phase flow. The main focus is to compare the difference of hydraulic losses and shapes of cavitating structures identified in the experiment and in the simulation.
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Andriotis, Adamantios. "Investigation of cavitation inside multi-hole injectors for large diesel engines and its effect on the near-nozzle spray Structure." Thesis, City University London, 2009. http://openaccess.city.ac.uk/1087/.

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Liverani, Luca. "Cavitation in Real-Size Diesel Injector Nozzles." Thesis, City University London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525149.

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Books on the topic "Cavitation nozzle"

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Fietz, T. R. An aid to the design of orifice plates according to ISO code 5167. Manly Vale, N.S.W., Australia: University of New South Wales, Water Research Laboratory, 1988.

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Book chapters on the topic "Cavitation nozzle"

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Adhikari, R. C., and D. H. Wood. "Nozzle Entry Effects and Cavitation Inception in Crossflow Hydroturbines." In Springer Proceedings in Energy, 80–92. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00105-6_5.

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Nishimura, Satoshi, Osamu Takakuwa, and Hitoshi Soyama. "Effect of Nozzle Geometry on Aggressivity of Cavitating Jet for Cavitation Erosion Test and Applications." In Advanced Experimental and Numerical Techniques for Cavitation Erosion Prediction, 283–302. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-8539-6_12.

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Chekh, Oleh, Serhii Sharapov, Maxim Prokopov, Viktor Kozin, and Dariusz Butrymowicz. "Cavitation in Nozzle: The Effect of Pressure on the Vapor Content." In Lecture Notes in Mechanical Engineering, 522–30. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-22365-6_52.

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Čaika, Valdas, Peter Sampl, and David Greif. "Coupled 1D/2D/3D Modeling of Common Rail Injector Flow and Nozzle Cavitation." In Lecture Notes in Electrical Engineering, 375–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-33841-0_27.

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Zhu, Shichun, Xuedong Liu, and Zhihong Zhang. "Experimental Investigation of Viscosity Reduction of Heavy Oil via Hydrodynamic Cavitation in Laval Nozzle." In Lecture Notes in Electrical Engineering, 1–9. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6318-2_1.

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Hutli, E. A. F., and M. S. Nedeljkovic. "Formula for Upstream Pressure, Nozzle Geometry and Frequency Correlation in Shedding/Discharging Cavitation Clouds Determined by Visualization of Submerged Cavitating Jet." In New Trends in Fluid Mechanics Research, 194–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75995-9_58.

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Örley, F., T. Trummler, M. S. Mihatsch, S. J. Schmidt, and S. Hickel. "LES of Cavitating Nozzle and Jet Flows." In Direct and Large-Eddy Simulation X, 133–39. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63212-4_16.

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Delale, Can F., Günter H. Schnerr, and Şenay Pasinlioğlu. "Shocks in Quasi-One-Dimensional Bubbly Cavitating Nozzle Flows." In Bubble Dynamics and Shock Waves, 205–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-34297-4_7.

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Delale, Can F., Şenay Pasinlioğlu, and Zafer Başkaya. "Mathematical Theory and Numerical Simulation of Bubbly Cavitating Nozzle Flows." In Supercavitation, 1–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23656-3_1.

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Wo, Hengzhou, Xianguo Hu, Hu Wang, and Yufu Xu. "Cavitation of Biofuel Applied in the Injection Nozzles of Diesel Engines." In Wear of Advanced Materials, 119–61. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118562093.ch4.

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Conference papers on the topic "Cavitation nozzle"

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Davis, Michael P., Patrick F. Dunn, and Flint O. Thomas. "Jet Fuel Cavitation in a Converging Diverging Nozzle." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37108.

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The focus of this research proposal is the experimental characterization of fuel cavitation in flow through a converging-diverging nozzle. Cavitation of fuel presents additional complexities (as compared to that in water) because fuel is a multi-component mixture. In any practical engineering environment, large quantities of solid microparticles are resident in the fuel. Gas nuclei trapped on these microparticles has been shown to enhance bubble production in water, and their effect on fuel cavitation is an issue that will be investigated. Measurements also will be made with cavitating water for comparison. A converging-diverging nozzle was chosen as the means for producing cavitation because its type of area constriction is similar to other flow devices such as valves and pumps. Cavitating C-D nozzle flows also have been modeled extensively in the literature. The data that will be acquired include axial pressure profiles, nozzle flow rate, high-speed images of the cavitating region, axial void fraction profiles, and axial velocity profiles. Pressure, velocity, and flow rate data will be used to determine the pressure ratios and limiting mass flow rates when the nozzle is choked. High speed images will be used to identify the structures present in the two-phase region (whether the gaseous voids are spherical bubbles or amorphous slugs. Axial void fraction data will provide information on gas evolution in the flow. Experimental data for cavitating nozzle flows are limited to water cases where bubble nucleation is not a primary source of the two-phase mixture. The proposed research hopes to provide detailed pressure, void-fraction, and velocity measurements for comparison with existing models. The main differences between fuel and water cavitation will be highlighted.
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Sou, Akira, Raditya Hendra Pratama, and Tsuyoshi Tomisaka. "Cavitation in a Nozzle of Fuel Injector." In 8th International Symposium on Cavitation. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2826-7_048.

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Peng, Guoyi, Hideto Ito, and Seiji Shimizu. "Numerical Simulation of High-Speed Cavitating Water-Jet Issuing From a Submerged Nozzle." 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/fedsm2012-72438.

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A simplified estimation for the compressibility of cavitating flow is proposed based on the bubble cavitation model and a compressible mixture flow method is developed for the numerical simulation of high-speed cavitating jet by coupling the simplified estimation of bubble cavitation to a compressible turbulent flow computation procedure. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase, which is governed by the compressibility of bubble-liquid mixture at the current status of local flow field. The method is applied to the simulation of high-speed submerged water jets issuing from an orifice nozzle. Both non-cavitating and cavitating jets are calculated under different cavitation numbers in order to clarify the cavitation property of submerged water jet. The results demonstrate that the intensity of cavitation denoted by the maximum value of gas volume fraction and the area of strong cavitation indicted by high value of gas volume fraction increase with the decrease of cavitation number. Under the effect of cavitation bubbles the discharge coefficient of orifice nozzle decreases with the cavitation number.
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Mauger, Cyril, Loïc Méés, StMéphane Valette, Marc Michard, Michel Lance, and Alexandre Azouzi. "Optical Investigation of a Cavitating Flow in a 2D Nozzle." In 8th International Symposium on Cavitation. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2826-7_276.

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Wilms, Jeffrey, Terry Beck, Christopher M. Sorensen, Mohammad H. Hosni, Steven J. Eckels, and Don Tomasi. "Experimental Measurements and Flow Visualization of Water Cavitation Through a Nozzle." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-40276.

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A typical refrigeration loop is composed of an evaporator, compressor, condenser, and an expansion valve. There are many possible refrigerants that can be used, but the physical properties of water make it ineffective in the traditional refrigeration loop. But if water could be used it would have many advantages as it is abundant, cheap, and is safe for the environment. As part of development of a new refrigeration loop using water, flow visualization and cavitation of water through nozzles are being investigated. Cavitation is generally defined as creating vapor from liquid, not through adding heat, but by decreasing the pressure. In a converging/ diverging nozzle as the cross sectional area is constricted the velocity of the flow will increase, decreasing the pressure. Therefore, by flowing water through the nozzle it will cavitate. Transforming liquid into gas requires a certain amount of energy, defined as the latent heat. When a liquid is turned to vapor by an increase in the temperature the latent heat is provided by the heat transfer to the system. As no energy is being added in the nozzle to cause the cavitation, the heat to create the vapor comes from the liquid, effectively causes a temperature drop. This article presents results for the flow visualization of the water cavitating as it goes through the nozzle. Under different flow conditions and nozzle geometries the cavitation manifested itself in different formations. When gasses were entrained in the water they formed bubbles, creating a nucleation site and moving through the nozzle, called travelling bubble cavitation. In venturi nozzles the cavitation nucleated off of the wall, forming attached wall cavitation. When water flowed out of an orifice, a turbulent water jet was formed which caused vapor to form around it, causing shear cavitation. When the water was rotated prior to the throat of an orifice, the orifice jet expanded radially and formed swirl cavitation.
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Sato, Keiichi, Naoya Takahashi, and Yasuhiro Sugimoto. "Effects of Diffuser Length on Cloud Cavitation in an Axisymmetrical Convergent-Divergent Nozzle." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-05507.

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Unsteady behavior of periodic cloud cavitation is typically observed in the field of fluid machinery under a high speed liquid flow such as a cavitating hydrofoil as well as cavitating water jet. The instability of cloud cavitation remains to be completely solved though it has been confirmed that there are two instabilities which is an intrinsic instability of cavitation and a system instability. Sato, et al. have found through previous investigations that the pressure wave at the collapse of shedding clouds can make a trigger to cause a reentrant motion. In the present study, the authors focus on a cavitating water jet to investigate the cavitation aspects in an axisymmetrical convergent-divergent nozzle and examine an unsteady behavior of cloud cavitation through high speed video observation and image analysis based on the frame difference method. Especially, the authors study the effect of nozzle divergent part (diffuser) as well as the upstream pressure effect on cloud cavitation in the nozzle. As a result the authors have found that there are two kinds in the shedding pattern and the reentrant motion pattern for cloud cavitation depending on the nozzle diffuser length.
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Sou, Akira, Shinichi Nitta, and Tsuyoshi Nakajima. "Bubble Tracking Simulation of Cavitating Flow in an Atomization Nozzle." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31018.

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Numerical simulation of transient cavitating flow in a axisymmetric nozzle was conducted in order to investigate the detailed motion of cavitation bubble clouds which may be dominant to atomization of a liquid jet. Two-way coupled bubble tracking technique was assigned in the present study to predict the unsteady cloud cavitation phenomena. Large Eddy Simulation (LES) was used to predict turbulent flow. Calculated pressure distribution and injection pressure were compared with measured ones. Then, calculated motion of cavitation bubble clouds was carefully investigated to understand the cavitation phenomena in a nozzle. As a result, the following conclusions were obtained: (1) Calculated result of pressure distribution along the wall, the relation between injection pressure vs. flow rate, and bubble distribution agreed with existing experimental result. (2) Cavitation bubble clouds were periodically shed from the tail of vena contracta, which usually formed by the coalescence of a few small bubble clouds. (3) Collapse of cavitation bubbles due to the re-entrant jet was observed in the numerical simulation.
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Villafranco, Dorien O., Huy K. Do, Sheryl M. Grace, Emily M. Ryan, and R. Glynn Holt. "Assessment of Cavitation Models in the Prediction of Cavitation in Nozzle Flow." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83223.

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Cavitation inside fuel injector nozzles has been linked not only to erosion of the solid surface, but also to improved spray atomization. To quantify the effects of the resulting occurrences, the prediction of cavitation through computational modeling is vital. Homogeneous mixture methods (HMM) make use of a variety of cavitation sub-models such as those developed by Kunz, Merkle, and Schnerr-Sauer, to describe the phase change from liquid to vapor and vice-versa in the fluid system. The aforementioned cavitation models all have several free-tuning parameters which have been shown to affect the resulting prediction for vapor volume fraction. The goal of the current work is to provide an assessment of the Kunz and Schnerr-Sauer cavitation models. Validation data have been obtained via experiments which employ both acoustic techniques (passive cavitation detection, or PCD) and optical techniques (optical cavitation detection, or OCD). The experiments provide quantitative information on cavitation inception and qualitative information as to overall vapor fraction as a function of flow rate, and nozzle geometry. It is shown that inception is fairly well captured but the amount of vapor predicted is far too low. A sensitivity analysis on the tuning parameters in the cavitation models leads to some explainable trends, however, several parameter sweeps results in outlier predictions. Recommendations for their usability and suggestions for improvement are presented.
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Peng, Guoyi, Hideto Ito, Seiji Shimizu, and Shigeo Fujikawa. "Numerical Investigation on the Structure of High-Speed Cavitating Water Jet Issuing From an Orifice Nozzle." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-33023.

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A practical mixture flow approach to the numerical simulation of turbulent cavitating flows is developed by coupling a simplified estimation of bubble cavitation to a compressible mixture flow computation. The mean flow of two-phase mixture is calculated by neglecting the slip between bubbles and surround liquid. Navier-Stokes equations for compressible fluids are used to describe the unsteady mean flow field and the RNG k-ε model is adopted for modeling of the flow turbulence. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the mean flow. The flow structure of submerged water jets issuing from an orifice nozzle is investigated numerically. Both non-cavitating and cavitating jets are calculated under different cavitation numbers in order to clarify the cavitation property of submerged water jet. The results demonstrate that the intensity of cavitation denoted by the maximum value of gas volume fraction and the area of strong cavitation indicted by high value of gas volume fraction increase with the decrease of cavitation number. Under the effect of cavitation bubbles the discharge coefficient of orifice nozzle decreases with the cavitation number.
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He, Zhixia, Jing Bai, Qian Wang, Qingmu Mu, and Yunlong Huang. "Numerical and Experimental Investigations of Cavitating Flow in a Vertical Multi-Hole Injector Nozzle." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30504.

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The presence of cavitation and turbulence in a diesel injector nozzle has significant effect on the subsequent spray characteristics. However, the mechanism of the cavitating flow and its effect on the subsequent spray is unclear because of the complexities of the nozzle flow, such as the cavitation phenomena and turbulence. A flow visualization experiment system with a transparent scaled-up vertical multi-hole injector nozzle tip was setup for getting the experimental data to make a comparison to validate the calculated results from the three dimensional numerical simulation of cavitating flow in the nozzle with mixture multi-phase cavitating flow model and good qualitative agreement was seen between the two sets of data. The critical conditions for cavitation inception were derived as well as the relationship between the discharge coefficient and non-dimensional cavitation parameter. After wards, the testified numerical models were used to analyze the effects of injection pressure, back pressure, cavitation parameter, Reynolds number, injector needle lift and needle eccentricity on the cavitating flow inside the nozzle. Combined with visual experimental results, numerical simulation results can clearly reveal the three-dimensional nature of the nozzle flow and the location and shape of the cavitation induced vapor distribution, which can help understand the nozzle flow better and eventually put forward the optimization ideas of diesel injectors.
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Reports on the topic "Cavitation nozzle"

1

Bastawissi, Hagar Alm El-Din, and Medhat Elkelawy. JAECFD Simulation Analysis of Cavitating Flow in a Real Size Diesel Engine Injector Nozzle. Warrendale, PA: SAE International, October 2012. http://dx.doi.org/10.4271/2012-32-0033.

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Bastawissi, Hagar, and Medhat Elkelawy. CFD Simulation Analysis of Cavitating Flow in a Real Size Diesel Engine Injector Nozzle. Warrendale, PA: SAE International, September 2010. http://dx.doi.org/10.4271/2010-32-0111.

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