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1
Rajakuperan, E. "Experimental And Computational Investigations Of Underexpanded Jets From Elliptical Sonic Nozzles." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/158.
Full textAbstract:
Three dimensional nozzles and jet flows have attracted the attention of many researchers due to their potential application to many practical devices. Rectangular nozzles are considered for short/vertical take off and landing aircrafts for achieving powered lift. Axisymmetric nozzles with lobes, tabs or slots and elliptical nozzles are considered for noise reduction in aircrafts and mixing augmentation in airbreathing rockets. Interaction of supersonic jets with solid
surface, as in the case of retro and ullage rockets in launch vehicles and interaction of multiple jets as in the case of launch vehicles with multiple booster rockets/multiple nozzle engines are of practical importance. Design of rockets and aircrafts employing these nozzles needs the understanding of the structure and behaviour of the complex three dimensional supersonic jets issuing from these nozzles. The problem is so complex that different investigators have addressed only some specific aspects of the problem and there is much more to be done to fully understand these flows. For example, in the case of rectangular nozzle with semi circular ends (known as elliptical nozzle), the investigations have been limited to a single nozzle of aspect ratio 3,0 and pressure ratio (ratio of the total pressure to ambient pressure) 3.0. Further, the measurements were made in the far field subsonic region beyond a distance of 20 times the equivalent nozzle radius (RJ.
For the present study, the elliptical sonic nozzle of the type mentioned above was chosen, as it offered simplicity for manufacturing and carrying out computations, but has all the complex features associated with the three dimensional jets. A systematic study to understand the mean flow structure and the effect of important governing parameters like
ratio and pressure ratio on the flow development process of the jet issuing from Navier-Stokes equations.
The experimental study revealed many interesting flow features. It was found that the Underexpanded jet issuing from elliptical sonic nozzle spreads rapidly in the minor axis plane while it maintains almost constant width or contracts in the major axis plane. However, the gross spreading of this jet is much higher compared to the axisymmetric jet. The higher spreading rates experienced in the minor axis plane compared to the major axis plane of this 'et, results in the jet width in the minor axis plane to become higher than that in the major axis plane. The longitudinal location, where this occurs is called the axis switching location. This kind of axis switching phenomenon is known to exist for subsonic elliptical jets. However, for the present supersonic jets, the axis switching locations are much closer to the nozzle exit compared to the subsonic cases reported. It was further found that this location strongly depends on the pressure and aspect ratios. A critical pressure ratio was found to exist for each nozzle at which the axis switching location is the farthest. Above the critical pressure ratio, the axis switching location was observed to move upstream with the increase in the pressure ratio and is controlled by the
complex interactions of shock and expansion waves near the nozzle exit. Below the critical pressure ratio, the axis switching location moves upstream with the decrease in pressure ratio and is controlled by some kind of instability in the minor axis plane.
The shock structure present in the underexpanded jet from an elliptical nozzle was also observed to depend on both pressure and aspect ratios. For some aspect ratios and pressure ratios, the shock pattern observed in both the major and minor axis planes are similar to that of an axisymmetric jet, where the incident barrel shock and the Mach reflection (from the edges of the Mach disk) are present. But for all other cases, this shock
continues to be seen only in the major axis plane. Whereas, in the minor axis plane, the incident shock is absent in the shock pattern.
Detailed measurement in the jet cross sectional planes, for the case of aspect ratio 2.0 nozzle, shows that the cross sectional shape changes along the length and it becomes almost a circle at the axis switching location. Further downstream, the jet spreads rapidly in the minor axis plane whereas no significant change in the width of the jet in the major axis plane is observed. Far downstream, the jet boundary appears like a distorted ellipse with its major and minor dimensions lying respectively in the minor and major axis planes of the nozzle. The elongated shape of the jet cross sections at locations downstream of the axis switching point gives the impression that the entire flow in the major axis plane is turned towards the minor axis plane. This effect appears to be predominant at high pressure ratios.
The computed near field shock structure in the planes of symmetry, pitot pressure distributions, cross sectional shape of the jet and the spreading pattern agree very well with the experimental results. In addition to this, the present computational method gives the detailed near field flow structure including the azimuthal extent of the incident shock, cross flow details and distributions of flow variables. It is shown that the present inviscid methodology can also predict the axis switching point accurately if it occurs before the formation of the Mach disk and it demonstrates that the jet growth phenomenon in the near field, atleast, is mainly controlled by the inviscid flow process. The computed results have shown that changes in the jet cross sectional shape in the near field is caused mainly by the interaction of compression and expansion waves with each other and with the constant pressure boundary. The inviscid method seems to be able to capture the complicated secondary cross flow structure (indicating presence of longitudinal vortices) of the elliptical jet.
The complex mean flow structure in the near field region of the jet issuing from elliptical nozzles and the effect of nozzle aspect ratio and pressure ratio on the structure are brought out clearly in the present study. The mechanism governing the spreading and the axis switching characteristics are also brought out. Thus the present experimental and computational investigations give a comprehensive understanding of the mean flow structure of the underexpanded jets issuing from elliptical nozzles. Further studies are required to understand the other aspects of the elliptical jets as well as other three-dimensional jets. Some of these studies are identified for future work.
2
Rajakuperan, E. "Experimental And Computational Investigations Of Underexpanded Jets From Elliptical Sonic Nozzles." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/158.
Full textAbstract:
Three dimensional nozzles and jet flows have attracted the attention of many researchers due to their potential application to many practical devices. Rectangular nozzles are considered for short/vertical take off and landing aircrafts for achieving powered lift. Axisymmetric nozzles with lobes, tabs or slots and elliptical nozzles are considered for noise reduction in aircrafts and mixing augmentation in airbreathing rockets. Interaction of supersonic jets with solid
surface, as in the case of retro and ullage rockets in launch vehicles and interaction of multiple jets as in the case of launch vehicles with multiple booster rockets/multiple nozzle engines are of practical importance. Design of rockets and aircrafts employing these nozzles needs the understanding of the structure and behaviour of the complex three dimensional supersonic jets issuing from these nozzles. The problem is so complex that different investigators have addressed only some specific aspects of the problem and there is much more to be done to fully understand these flows. For example, in the case of rectangular nozzle with semi circular ends (known as elliptical nozzle), the investigations have been limited to a single nozzle of aspect ratio 3,0 and pressure ratio (ratio of the total pressure to ambient pressure) 3.0. Further, the measurements were made in the far field subsonic region beyond a distance of 20 times the equivalent nozzle radius (RJ.
For the present study, the elliptical sonic nozzle of the type mentioned above was chosen, as it offered simplicity for manufacturing and carrying out computations, but has all the complex features associated with the three dimensional jets. A systematic study to understand the mean flow structure and the effect of important governing parameters like
ratio and pressure ratio on the flow development process of the jet issuing from Navier-Stokes equations.
The experimental study revealed many interesting flow features. It was found that the Underexpanded jet issuing from elliptical sonic nozzle spreads rapidly in the minor axis plane while it maintains almost constant width or contracts in the major axis plane. However, the gross spreading of this jet is much higher compared to the axisymmetric jet. The higher spreading rates experienced in the minor axis plane compared to the major axis plane of this 'et, results in the jet width in the minor axis plane to become higher than that in the major axis plane. The longitudinal location, where this occurs is called the axis switching location. This kind of axis switching phenomenon is known to exist for subsonic elliptical jets. However, for the present supersonic jets, the axis switching locations are much closer to the nozzle exit compared to the subsonic cases reported. It was further found that this location strongly depends on the pressure and aspect ratios. A critical pressure ratio was found to exist for each nozzle at which the axis switching location is the farthest. Above the critical pressure ratio, the axis switching location was observed to move upstream with the increase in the pressure ratio and is controlled by the
complex interactions of shock and expansion waves near the nozzle exit. Below the critical pressure ratio, the axis switching location moves upstream with the decrease in pressure ratio and is controlled by some kind of instability in the minor axis plane.
The shock structure present in the underexpanded jet from an elliptical nozzle was also observed to depend on both pressure and aspect ratios. For some aspect ratios and pressure ratios, the shock pattern observed in both the major and minor axis planes are similar to that of an axisymmetric jet, where the incident barrel shock and the Mach reflection (from the edges of the Mach disk) are present. But for all other cases, this shock
continues to be seen only in the major axis plane. Whereas, in the minor axis plane, the incident shock is absent in the shock pattern.
Detailed measurement in the jet cross sectional planes, for the case of aspect ratio 2.0 nozzle, shows that the cross sectional shape changes along the length and it becomes almost a circle at the axis switching location. Further downstream, the jet spreads rapidly in the minor axis plane whereas no significant change in the width of the jet in the major axis plane is observed. Far downstream, the jet boundary appears like a distorted ellipse with its major and minor dimensions lying respectively in the minor and major axis planes of the nozzle. The elongated shape of the jet cross sections at locations downstream of the axis switching point gives the impression that the entire flow in the major axis plane is turned towards the minor axis plane. This effect appears to be predominant at high pressure ratios.
The computed near field shock structure in the planes of symmetry, pitot pressure distributions, cross sectional shape of the jet and the spreading pattern agree very well with the experimental results. In addition to this, the present computational method gives the detailed near field flow structure including the azimuthal extent of the incident shock, cross flow details and distributions of flow variables. It is shown that the present inviscid methodology can also predict the axis switching point accurately if it occurs before the formation of the Mach disk and it demonstrates that the jet growth phenomenon in the near field, atleast, is mainly controlled by the inviscid flow process. The computed results have shown that changes in the jet cross sectional shape in the near field is caused mainly by the interaction of compression and expansion waves with each other and with the constant pressure boundary. The inviscid method seems to be able to capture the complicated secondary cross flow structure (indicating presence of longitudinal vortices) of the elliptical jet.
The complex mean flow structure in the near field region of the jet issuing from elliptical nozzles and the effect of nozzle aspect ratio and pressure ratio on the structure are brought out clearly in the present study. The mechanism governing the spreading and the axis switching characteristics are also brought out. Thus the present experimental and computational investigations give a comprehensive understanding of the mean flow structure of the underexpanded jets issuing from elliptical nozzles. Further studies are required to understand the other aspects of the elliptical jets as well as other three-dimensional jets. Some of these studies are identified for future work.
3
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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4
Marrion, Maynard. "Separation control in over-expanded supersonic nozzles." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490110.
Full textAbstract:
Needle-free drug and vaccine delivery devices have been developed by the Department of Engineering Science at The University of Oxford in collaboration with PowderJect Pharmaceuticals plc. In them, micro-particles of pharmaceuticai agent are accelerated, by a supersonic flow of gas in a nozzle, to velocities sufficient for them to penetrate the outer layers of the skin. If the gas flow is over-expanded relative to the atmosphere to which it discharges, shock waves form inside the nozzle, which cause the flow to separate from the wall. The resulting gas-particle flow field is highly non-uniform, leading to suboptimal drug or vaccine delivery and even damage to the target skin.
5
Fasci, Giuseppe Carmine. "CFD modelling of Retention Aids Dosage Nozzles." Thesis, KTH, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98660.
Full textAbstract:
The objective of this project is to design, using computational fluid dynamics (CFD), a set of retention aid dosage nozzles that minimize shear levels during their operation. This includes the effect of dosage nozzle size, contour and dosage velocity - absolute and relative to the stock flow. As a starting point, the three different dosage nozzles currently implemented on the Innventia FEX paper-machine have been studied using CFD. Problem areas, defined as regions of high viscous and/or turbulent shear, with these designs should be identified, and solutions to their improvement have been realized. The computational models considered here include non Newtonian models of the retention aid solution, as well as turbulent modeling of the stock flow. Novel configurations have been implemented which attempt to minimize the strain rate and shear stress during dosage and at the same time improve the mixing quality of the retention aid polymers. While the velocity of the side jet is determined to be the main cause of high strain rates and shear stresses, a good mixing can be reached by varying the position of the nozzles and the diameter penetrating the stock flow. The best compromise of mixing and shear stress has been reached with a triple side-wall nozzles configuration.
6
Izola, Dawson Tadeu. "Investigação da indução de engasgamento em tubeira DeLAVAL para motor-foguete por intermédio do prolongamento da garganta." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-16022018-143941/.
Full textAbstract:
A condição ótima de funcionamento de uma tubeira em um motor foguete com escoamento isentrópico, implica que a velocidade na garganta (seção de menor área) seja equivalente à velocidade do som local, condição de Mach 1 e bocal engasgado. Pode-se alcançar essa condição reduzindo a área da seção do escoamento até a área crítica, velocidade sônica. Após a garganta acontece a expansão e se alcança velocidades supersônicas no divergente. Para manter a condição de Mach 1 na garganta em motores foguetes, trabalha-se com pressões superiores à necessária para se engasgar o bocal. Isto ocorre porque tenta-se compensar instabilidades ou variações de volumes produzidos na combustão ou queima. Usando uma pressão de trabalho maior, impõe-se que a condição de Mach 1 fique mantida durante toda a queima do combustível, isso implica em usar tubos mais resistentes à pressão e maior massa do tubo-motor. Observou-se experimentalmente que em algumas situações construtivas se podem modificar a pressão e temperatura necessárias para engasgar o bocal aumentando o comprimento da garganta. O comprimento do estrangulamento pode estabelecer uma condição para formação e evolução da camada limite e esta condição restringir a área nominal, modificando o regime do escoamento. Um equipamento especialmente desenvolvido para esse ensaio compara resultados de cinco modelos de motores, divididos em dois grupos, cada grupo com áreas de entrada, garganta e saída iguais, porém com comprimentos diferentes de garganta. Em análise experimental, observou-se que a pressão de trabalho e a temperatura são influenciadas pelo comprimento da garganta, interferindo na relação entre as pressões internas e de garganta e apresentando condições de engasgamento mensuráveis. Essas medidas foram conduzidas no presente estudo de doutorado.The optimum operational condition of a rocket motor nozzle with isentropic flow implies that the velocity at the throat (the section with smallest area) is equivalent to the speed of the local sound. This speed is also called Mach 1 and it is said that at this condition the nozzle is choking. One can achieve this condition by reducing the cross-sectional area of the flow to the critical area resulting in a sonic speed. Beyond the nozzle throat, in the divergent section of the motor, flow expansion occurs and reaches supersonic speeds. To maintain the condition of Mach 1 at the throat, higher pressures than the one necessary to choke the nozzle are applied. This practice is done in order to compensate for jitter or variations of volumes produced in the combustion process. Using a higher operating pressure guarantees that a Mach 1 speed is maintained throughout the combustion process. Consequently, due to this higher operating pressure, more resistant tubes are needed to withstand this higher pressure and an increase in the motor weight is inevitable. It was observed experimentally that some constructional modifications of the motor can alter the pressure and temperature required for choking. This was noted with increasing the bottleneck length of the nozzle throat which was able to establish a condition for the formation and evolution of the boundary layer, restricting the nominal area and thus modifying the flow regime. In this study, the results of five engine models are compared using a specially designed equipment. The rockets were divided into two groups, each with equal inlet, throat, and exit areas, but having different throat lengths. In experimental analysis, it was observed that the working pressure and temperature are influenced by the length of the throat, interfering in the relationship between the internal pressures and throat presenting measurable choking conditions which were conducted in this doctorate thesis study.
7
Thacker, John Edward. "Design of medium pressure nozzles for cooling towers." Thesis, Stellenbosch : Stellenbosch University, 1997. http://hdl.handle.net/10019.1/55448.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 1997.One copy microfiche.
ENGLISH ABSTRACT: This project concerns the investigation of parameters controlling the behaviour of full-cone spray nozzles of the type used in cooling towers. In the present study large medium pressure hollow and full cone nozzles were investigated. A literature survey provided insight into the relationships between the nozzle dimensions and their spray characteristics, while equations found in the literature were used to correlate the experimental data. It was found that the spray cone angle of hollow cone nozzles could be manipulated by using rounded orifice outlets and this finding lead to the development of a uniquely profiled outlet that actually produces a square spray pattern. More experimental work was done to determine the relationship between the central jet of a full-cone nozzle and the other major nozzle dimensions. These results were then correlated and formulated into a set of guidelines for designing full-cone nozzles.
Digitized at 300 dpi Colour PDF format (OCR), using ,KODAK i 1220 PLUS scanner. Digitised, Ricardo Davids on request from Corinna 01 October 2014
AFRIKAANSE OPSOMMING: Hierdie projek behels 'n studie van belangrike parameters in volkegel sproeimondstukke soos gebruik in koeltorings. In die huidige studie word groot mediumdruk holkegel en volkegel sproeimondstukke ondersoek. 'n Literatuurstudie het die nodige insig verskaf omtrent die verwantskap tussen mondstuk dimensies en hul spuitkarakteristieke, terwyl vergelykings uit die literatuur gebruik is om die eksperimentele data te korreleer. Dit was gevind dat die sproeir kegelhoek van die holkegelmondstuk verander kon word deur gebruik te maak van geronde uitlate. Afleidings wat gemaak is het gely tot die ontwikkeling van 'n unieke geprofielde uitlaat wat 'n vierkantige sproeipatroon gelewer het. Bykomstige eksperimentele werk is gedoen om die verwantskap tussen die sentralestraal van 'n volkegelmondstuk en die ander hoof mondstukdimensies te bepaal. Die reultate is verwerk om riglyne vir die ontwerp van vierkantige patroon volkegel mondstukke daar te stel.
8
Fry, Richard N. "Dense gas effects in a converging-diverging nozzle." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12232009-020448/.
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9
Newbold, Gregory. "Mixing and combustion in precessing jet flows /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phn534.pdf.
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10
Nichols, James Franklin. "Two-dimensional analysis of turbine blades and nozzles." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17673.
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11
Chen, Guohua 1963. "Impingement heat transfer with re-entry channel nozzles." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59261.
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Intensity of axial turbulence at the nozzle exit and impingement heat transfer rate were measured for the re-entry slot channel nozzle, with nozzle length, L, nozzle width, w, and jet Reynolds number, Re, as parameters. With increasing Reynolds number over the range 5000-20000 the turbulence intensity decreases, but only slightly. For the shortest nozzles, i.e. orifices, turbulence varies greatly across the nozzle width, from 0% near the nozzle walls. A nozzle length of 3w-4w is sufficient to produce relatively flat profiles. Turbulence intensity is better characterized at the mid-plane, I$ sb{ rm jmp}$, than at the center line, I$ sb{ rm jcL}$. By varying w between 6 and 11 mm, and L from 13w down to an orifice, I$ sb{ rm jmp}$ varies between 4% and 9%.Impingement heat transfer is not significantly influenced by L/w.
This geometry of nozzle operated at spacings, H/w of 3 and 6, gives heat transfer rates that match the maximum obtained with the ASME standard contoured entry nozzle at H/w precisely of 8.
12
Giannadakis, Emmanouil. "Modelling of cavitation in automotive fuel injector nozzles." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420301.
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13
Zhou, Quanbao. "Spray formation processes within agricultural flat fan nozzles." Thesis, University of Birmingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511470.
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14
Duncombe, John Trevor. "Inclusion behaviour in steel flows through convergent nozzles." Thesis, Sheffield Hallam University, 1989. http://shura.shu.ac.uk/3464/.
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It is well established that nozzle blockage in Al-killed continuously cast steels is caused by the deposition of preexisting Al 0 inclusions at the narrowest part of the nozzle. Thisa adhere strongly at the wall by interfacial forces. The theory examined in this thesis is that during the curved flow path through the nozzle, inclusions move towards the nozzle wall by the action of centripetal force. A mathematical model has been developed which takes account of centripetal, gravitational, and drag forces. A computer programme has been written to predict particle behaviour in nozzle flows. To study the behaviour of second phase particles, a water model using a perspex tundish and an interchangeable glass nozzle has been built. Turbulence has been almost completely removed from the experimental tundish. Hydrogen bubbles electrolytically generated in water have been used to simulate the inclusions in steel and their flow paths through the nozzle have been recorded by cine photography. With frame by frame analysis of the films, the effects of bubble size, (50 pm to 1000 um), and flow velocity have been studied. Two experimental nozzles have been tested which have demonstrated the importance of limiting the centripetal force. It has been shown that there is a good relationship between hydrogen bubble behaviour and model predictions. This has been particularly true of small bubbles near the nozzle wall. By comparing the results with other experimental work it has been shown that centripetal forces can have a significant effect on the rate of blocking. Practical suggestions for reducing the turbulent behaviour in steel tundishes and nozzles are made. The merits of an improved nozzle design which takes advantage of the results of the model work are discussed.
15
Smith, Larry R. "Fluidically augmented nozzles for pulse detonation engine applications." Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/10696.
Full textAbstract:
Pulse Detonation Engines (PDE) operate in a cyclic manner resulting in large changes in the combustion chamber pressure. The widely varying pressure ratio between the chamber and nozzle exit makes it difficult to efficiently produce thrust since a fixed area ratio exhaust nozzle would operate off design nearly the entire cycle. Therefore, a nozzle with the capability to create the necessary area ratio throughout the cycle is required to produce an effective and efficient thrust profile. A dynamically varying nozzle was evaluated which investigated the possibility of using air injection into the diverging portion of the nozzle in order to effectively adjust the nozzle's exit area and provide the primary engine combustion products the most efficient area ratio throughout the combustion cycle. A two-dimensional nozzle and combustion section was created and simulated using computational fluid dynamics software to analyze the flow for various air injection pressures and velocities. A test section was designed and assembled for actual testing of the nozzle with the air injection ports and used a shadowgraph technique to observe the time-varying gas dynamics in the nozzle. The results of each were compared and analyzed to determine the validity of the CFD analysis. Subsequent computational analysis was conducted to find the most optimal injection conditions to achieve the most effective variable nozzle design for maximizing the impulse per cycle.
16
Wang, YinChun Ph D. Massachusetts Institute of Technology. "Study of deposit formation inside diesel injectors nozzles." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79512.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 157-163).
Diesel engines are widely used in heavy duty transportation applications such as in trucks, buses and ships because of their reliability and high torque output. A key diesel technology is the injection system which is constantly improved to produce better spray quality and deeper spray penetration in the combustion chamber by using high injection pressure and improving the design of the nozzle holes. The hole size has been continuously reduced; future diameters less than 100 um are expected. Smaller nozzle holes are vulnerable to deposit formation, which will reduce the flow rate and affect the spray pattern. The objective of this study is to understand the processes that would lead to deposit formation on the injector nozzle surfaces. In specific, a detailed mechanism is proposed after observing engine and injector simulation results. Models for the physical processes and chemical mechanisms responsible for the deposit formation are developed. These models are incorporated into a integrated software package to facilitate calculations of deposit formation rates under different conditions. A benchscale test rig is also constructed to measure the deposit formation of different fuels and detergents. Experiments show that the test procedure can differentiate good detergents from ineffective ones; hence it can be used to pre-screen the detergents and fuels before engine tests. Thus the cost of testing could be reduced substantially. This study is the first to develop a comprehensive quantitative model for injector nozzle deposit formation and a bench scale testing apparatus encompassing the key deposit formation processes of film formation, evaporation and washing.
by YinChun Wang.
Ph.D.
17
McClure, James R. III. "Dynamic fluidic nozzles for pulse detonation engine applications." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/55200.
Full textAbstract:
Approved for public release; distribution is unlimited.An efficient nozzle design is critical for enhancing the benefits of Pulse Detonation Engines (PDEs) and enabling their use as future propulsion or power generation systems. Due to the inherent variation in chamber pressure for Pulse Detonation Combustors, it has been difficult to design a nozzle, which has the capability to provide an appropriate exit-to-throat area ratio suited for both the detonation blow-down event and refresh pressures associated with the cyclic operation of a PDE. A two-dimensional PDE exit nozzle was designed, modeled, and constructed in an attempt to increase the overall efficiency of converting thermal energy to kinetic energy by providing a fluidic method to dynamically vary the effective nozzle area ratio. A fluidic nozzle configuration was evaluated, which had the ability to inject a small amount of air into the diverging section of the nozzle in order to dynamically create a more desirable exit-to-throat area ratio. Experimental testing was conducted on various injection flow rates, and a shadowgraph system was used to observe the fluid flow characteristics within the nozzle. Computer simulations were used to analyze the fluid flow properties within the nozzle. A comparison of the computer simulations and the experimental results was performed and demonstrated good agreement.
Lieutenant, United States Navy
18
Chinn, John Joss. "The internal flow physics of swirl atomizer nozzles." Thesis, University of Manchester, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488302.
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The internal flow of pressure swirl atomizers is studied with the ultimate aim of developing a design tool for such atomizers, particularly to enable the production of the finest possible water sprays (for any given supply pressure) for fire suppression purposes. The primary direction of the research was in computationally modelling this flow with a two-dimensional assumption and a methodology is described which is capable of determining the velocity profiles and, for the first time in the literature, the air-core topology and discharge coefficient, for nozzles which approximate the axially-symmetric condition. The results are compared with the experimental results from both the literature and also from research which was carried out under the supervision of the author. The predictions show important flow features, which are found in the experiments and have not been recognised in the "classically" assumed internal flow. These include concentration of the axial flow near the air-core and toroidal vortices, similar to Taylor-Göertler vortices found in Taylor-Couette flow, which are visible in planes through the nozzle axis. The secondary direction of the research is in both reviewing and improving upon simplified analytical techniques which have been used to estimate the size of the air-core radius at the nozzle exit together with the values of the discharge coefficient and the cone angle of the resultant spray. A critical review is given of many of the existing analytical techniques and a new analytical theory is presented which is based upon a balance of the axial momentum across a control volume. The results of the new theory are compared with the experimental findings reported in the literature and show the need to include the swirl chamber/nozzle orifice ratio as an independent variable. Suggestions are given on how the computational methodology might be employed to determine the spray drop size for a given atomizer design and on the direction the computational work might take in order to predict a full two-phase internal flow using volume of fluid (VOF) techniques.
19
Scholtz, Kelly Burchell. "Optimisation of solid rocket motor blast tube and nozzle assemblies using computational fluid dynamics." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2487.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.A framework for optimising a tactical solid rocket motor nozzle is established and investigated within the ANSYS Workbench environment. Simulated results are validated against thrust measurements from the static bench firing of a full-scale rocket. Grid independence is checked and achieved using inflation based meshing. A rocket nozzle contour is parametrized using multiple control points along a spline contour. The design of experiments table is populated by a central composite design method and the resulting response surfaces are used to find a thrust optimised rocket nozzle geometry. CFD results are based on Favre-mass averaged Navier-Stokes equations with turbulence closure implemented with the Menter SST model. Two optimisation algorithms (Shifted Hammersley Sampling and Nonlinear Programming by Quadratic Lagrangian) are used to establish viable candidates for maximum thrust. Comparisons are made with a circular arc, Rao parabolic approximation and conical nozzle geometries including the CFD simulation there-off. The effect of nozzle length on thrust is simulated and optimised within the framework. Results generally show increased thrust as well as demonstrating the framework's potential for further investigations into nozzle geometry optimisation and off-design point characterisation.
20
Yanson, Logan M. "Effects of Liquid Superheat on Droplet Disruption in a Supersonic Stream." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-042905-151247/.
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Lang, Derek Edward. "Wake closure conditions in plug nozzle flowfields /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/10005.
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22
Bae, Yoon-Yeong. "Performance of an aero-space plane propulsion nozzle /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1989.
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23
Östlund, Jan. "Supersonic flow separation with application to rocket engine nozzles." Doctoral thesis, KTH, Mechanics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3793.
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The increasing demand for higher performance in rocketlaunchers promotes the development of nozzles with higherperformance, which basically is achieved by increasing theexpansion ratio. However, this may lead to flow separation andensuing instationary, asymmetric forces, so-called side-loads,which may present life-limiting constraints on both the nozzleitself and other engine components. Substantial gains can bemade in the engine performance if this problem can be overcome,and hence different methods of separation control have beensuggested. However, none has so far been implemented in fullscale, due to the uncertainties involved in modeling andpredicting the flow phenomena involved.
In the present work the causes of unsteady and unsymmetricalflow separation and resulting side-loads in rocket enginenozzles are investigated. This involves the use of acombination of analytical, numerical and experimental methods,which all are presented in the thesis. A main part of the workis based on sub-scale testing of model nozzles operated withair. Hence, aspects on how to design sub-scale models that areable to capture the relevant physics of full-scale rocketengine nozzles are highlighted. Scaling laws like thosepresented in here are indispensable for extracting side-loadcorrelations from sub-scale tests and applying them tofull-scale nozzles.
Three main types of side-load mechanisms have been observedin the test campaigns, due to: (i) intermittent and randompressure fluctuations, (ii) transition in separation patternand (iii) aeroelastic coupling. All these three types aredescribed and exemplified by test results together withanalysis. A comprehensive, up-to-date review of supersonic flowseparation and side-loads in internal nozzle flows is givenwith an in-depth discussion of different approaches forpredicting the phenomena. This includes methods for predictingshock-induced separation, models for predicting side-loadlevels and aeroelastic coupling effects. Examples are presentedto illustrate the status of various methods, and theiradvantages and shortcomings are discussed.
A major part of the thesis focus on the fundamentalshock-wave turbulent boundary layer interaction (SWTBLI) and aphysical description of the phenomenon is given. Thisdescription is based on theoretical concepts, computationalresults and experimental observation, where, however, emphasisis placed on the rocket-engineering perspective. This workconnects the industrial development of rocket engine nozzles tothe fundamental research of the SWTBLI phenomenon and shows howthese research results can be utilized in real applications.The thesis is concluded with remarks on active and passive flowcontrol in rocket nozzles and directions of futureresearch.
The present work was performed at VAC's Space PropulsionDivision within the framework of European spacecooperation.
Keywords:turbulent, boundary layer, shock wave,interaction, overexpanded,rocket nozzle, flow separation,control, side-load, experiments, models, review.
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Svensson, Hanna. "Plush Plate Alternatives : – New solutions for vacuum cleaner nozzles." Thesis, KTH, Maskinkonstruktion (Inst.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100888.
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Detta examensarbete utfördes på Electrolux Floor Care and Small Appliences AB i Stockholm på deras primärutvecklingsavdelning. Syftet med projektet var att ta fram ett alternativ till dagens plysh-plattor, placerade på dammsugarmunstycket, som har som funktion att ta upp hår och fibrer från, i första hand, mattor. Electrolux utvecklingsprocess, Product Creation Process, användes genom hela arbetet med några mindre anpassningar. Initialt gjordes en undersökning av hur Electrolux munstycken fungerar idag för att få en grundläggande förståelse för hur en lösning skulle kunna se ut och hur den skulle kunna påverka dammupptagningen. En brainstorming gjordes och ungefär 11 idé-förslag togs fram. Därefter påbörjades tester av både material- och formberoende lösningar. Flera av de mest lovande koncepten som sedan utvecklades kommer att utelämnas ur denna rapport då uppgifterna ansågs som känsliga på grund av eventuella patentansökningar. Koncepten togs fram och utvärderades med hjälp av några av de metoder som presenteras i början av detta arbete. Detta ledde slutligen till två koncept av vilka ett antal prototyper tillverkades och testades. Den slutliga lösningen visade sig fungera bra i tester. Det var från början meningen att det skulle vara två lösningar utvecklade från de två slutkoncepten. Dock kunde inte det företag som lovat producera den ena lösningen leverera i tid och detta gjorde att detta koncept inte kunde testas och utvärderas inom ramen för detta arbete. Konceptet i sig var dock så intressant att vidare tester skall utföras både på detta och på slutkonceptet.This Final thesis was performed at Electrolux Floor Care and Small Appliances AB in Stockholm in their primary development department. The purpose with the project was to find an alternative for today’s plush plate, placed on the vacuum cleaner nozzle, whose function is to pick up hair and fiber mainly from carpets. The Electrolux development process, the Product Creation Process, was used throughout the entire project with minor adjustments to fit the time plan and size of the project. Initially a study was made of the Electrolux vacuum cleaner nozzles to get a basic understanding of how a solution could look and how it could affect the dust pick-up capacity of the nozzle. A brainstorming session was executed and 11 suggestions for ideas were created. After this a number of tests where performed, both material- and shape-oriented ones. A number of the more promising concepts that was developed further will be excluded from this thesis due to patent issues. Concepts was developed and evaluated with help of the methods that are being presented in the beginning of this thesis. This finally led to two concepts of which a number of prototypes were constructed and tested. The final solution proved to function well in tests. From the beginning it was meant to be two solutions developed from the two final concepts. The company that was supposed to deliver one of them could not do so within the time limits and this led to the fact that this concept could not be tested and evaluated within the timeframe of this project. The concept proved to be so interesting though, that it was decided to go on with further testing both on this concept and the other one.
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Wu, Keng-Tung. "Bubble coalescence from multiple entry nozzles in fluidized beds." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286488.
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CASTRO, ARISTAGORAS MORAES DE. "STRESS ANALYSIS NOZZLES IN PRESSURE VESSELS WITH CONICAL CAPS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1992. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25613@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO presente trabalho tem por objetivo o estudo de tensões críticas em bocais cilíndricos soldados a vasos de pressão, também cilíndricos, com tampas de geometria cônica submetidos a pressão interna e a um carregamento axial externo. O problema é atacado analiticamente através da teoria de cascas de revolução, particularizada para cascas finas axissimétricas. É utilizado o método de flexibilidade para imposição da continuidade dos esforços e deslocamentos nas junções bocal/tampa e tampa/vaso. Foi desenvolvido um programa de computador que fornece as tensões máximas que ocorrem no bocal, bem como as resultantes de tensão, momentos, deslocamentos e rotações ao longo da estrutura. Observou-se que para uma dada configuração do sistema (diâmetros do bocal e vaso, e ângulos da tampa cônica) existe uma relação ótima entre as espessuras do bocal e da tampa, para a qual o fator de concentração de tensões é mínimo. Esta relação é independente da rasão entre os carregamentos axial e a pressão.
The present work is concerned whit critical stresses due to the combined affect of axial loads and intornal pressure in nossles welded to cilindrical pressure vessels whit conical hoads. The problem is treatod analytically through, axisimetric, thin ahell theory. The method of flexibility is employed to enforce the continuity of loads, moments, displacements and rotations at the junctions. A computer code has been developed for the calculation of the critical atresses in the nozzle, as well as the stresses resultants, moments, displacements, and the rotations along the atracture. It has been observed that for a griven configuration (nozzle and vessel diameters and angle of the conical head), there is an optimum between the nozzle and head thickness for which the stress concentration factor is minimum. This ratio is independent of the relation between the axial hoad and internal pressure.
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Espinosa, Edgard. "Design Optimization of Submerged Jet Nozzles for Enhanced Mixing." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/501.
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The purpose of this thesis was to identify the optimal design parameters for a jet nozzle which obtains a local maximum shear stress while maximizing the average shear stress on the floor of a fluid filled system. This research examined how geometric parameters of a jet nozzle, such as the nozzle's angle, height, and orifice, influence the shear stress created on the bottom surface of a tank. Simulations were run using a Computational Fluid Dynamics (CFD) software package to determine shear stress values for a parameterized geometric domain including the jet nozzle. A response surface was created based on the shear stress values obtained from 112 simulated designs. A multi-objective optimization software utilized the response surface to generate designs with the best combination of parameters to achieve maximum shear stress and maximum average shear stress. The optimal configuration of parameters achieved larger shear stress values over a commercially available design.
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Dingilian, Kayane Kohar. "Homogeneous Nucleation of Carbon Dioxide (CO2) in Supersonic Nozzles." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1607019789125519.
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Sinha, Somnath. "Experimental And Modeling Study Of Condensation In Supersonic Nozzles." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1217268763.
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Hoyt, Robert P. "Optimization of applied magnetic nozzles for coaxial plasma accelerators /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/9971.
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Roth, Hartwig. "Experimental and computational investigation of cavitation in diesel injector nozzles." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/8249.
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Nadarajah, Chithranjan. "A design study of nozzles and attachments in pressure vessels." Thesis, University of Strathclyde, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338935.
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Curodeau, Alain. "Three dimensional printing : machine control from CAD model to nozzles." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13031.
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Alkotami, Abdulmalik. "An investigation of cavitation cooling effect in converging-diverging nozzles." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/32780.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Mohammad H. Hosni
A traditional cooling/refrigeration cycle has four main system components which are an evaporator, a compressor, a condenser, and an expansion valve. This type of cycle requires use of refrigerants which have been found to be harmful to the environment, including causing damage to the atmospheric ozone layer. The main objective of the project was to investigate a water-based non-vapor compression cooling system. Water as a working fluid has the advantages of being inexpensive and environmentally safe for use, as compared to commercially available chemical refrigerants. The water-based cooling system investigated employed cavitation phenomena in converging-diverging glass nozzles. Cavitation is an important phenomenon in fluids, and is common occurring in many devices such as pumps, refrigeration expansion valves, and capillary tubes. It occurs when the static pressure of the fluid falls below the vapor pressure, into a metastable liquid state. Cavitation can be in the form of traveling bubble cavitation, vortex cavitation, cloud cavitation, or attached wall cavitation. In this thesis, the focus was first on visualizing cavitation for water flowing through converging- diverging glass nozzles. These nozzles had throat diameters between 2 mm and 4 mm. Two systems were used: (1) a continuous flow system, where water was driven by a centrifugal pump, and (2) a transient blow down system, where water flow was initiated using a suction pump. A high-speed camera was used to record videos and images of the associated cavitation phenomena. A thermal infrared camera was used in an attempt to measure temperature drop in the nozzle while the system was running The second part of this thesis focused on the understanding of the fundamental thermodynamics phenomena and on the development of practical knowledge relevant to the cavitation process. Two equations of state were used in the analysis, the van der walls equation of state, and the Peng Robinson equation of state. Equations of state were used to predict the transition from vapor to liquid. At a given temperature, the equations were solved for a pressure value corresponding to saturated liquid and saturated vapor specific volume values. Then, the equations were used to determine the spinodal liquid and vapor lines, which represent the metastabillity limits for the liquid and vapor. The characteristic equations of state, combined with implementation of the Law of Corresponding States and thermodynamic theory, were used to estimate the temperature reduction available for refrigeration.
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Hartawan, Laksmono Santoso. "Experimental Study of Methanol Condensation and Nucleation in Supersonic Nozzles." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282055155.
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MASPOLI, ORSO JEAN. "Pressure Mapping Investigation of Innovative Nozzles For Oil Drill-Bit." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029443895.
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Ren, Ning. "Analysis of the initial spray from canonical fire suppression nozzles." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7388.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Fire Protection Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Barber, Matthew James. "Experimental investigation of normal, sonic injection through a wedge-shaped nozzle into supersonic flow." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08222009-040226/.
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Hu, Xiaowei. "A study of nozzle jet application to winter maintenance vehicles." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447630.
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Bilgin, Murat. "Stationary and rotating hot jet ignition and flame propagation in a premixed cell /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9986.
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Tsioli, Ellie. "Investigation of indeterminate-origin coaxial nozzles for jet-mixing enhancement purposes." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539572.
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Petropoulou, Stamatina. "Adjoint-based geometry optimisation with applications to automotive fuel injector nozzles." Thesis, City University London, 2006. http://openaccess.city.ac.uk/8492/.
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Methods of Computational Fluid Dynamics (CFD) have matured, over the last 30 years, to a stage where it is possible to gain substantial insight into fluid flow processes of engineering relevance. However, the motives of fluid dynamic engineers typically go well beyond the level of improved understanding, to the pragmatic aim of improving the performance of the engineering systems in consideration. It is in recognition of these circumstances that the present thesis investigates the use of automated design optimisation methodologies in order to extend the power of CFD as an engineering design tool. Optimum design problems require the merit or performance of designs to be measured explicitly in terms of an objective function. At the same time, it may be required that one or more constraints should be satisfied. To describe allowable variations in design, shape parameterisation using basic geometric entities such as straight lines and arcs is employed. Taking advantage of previous experience in the research group concerning cavitating flows, a fully automated method for nozzle design/optimisation was developed. The optimisation is performed by means of discharge coefficient (Cd) maximisation. The objective is to design nozzle hole shapes that maximise the nozzle Cd for a given basic nozzle geometry (i.e. needle and sac profile) and reduce or even eliminate the negative pressure region formed at the entry of the injection hole. The deterministic optimisation model was developed and implemented in the in-house RANS CFD code to provide nozzle shapes with pre-defined flow/performance characteristics. The required gradients are calculated using the continuous adjoint technique. A parameterisation scheme, suitable for nozzle design, was developed. The localised region around the hole inlet, where cavitation inception appears, is parameterised and modified during the optimisation procedure, while the rest of the nozzle remains unaffected. The parameters modifying the geometry are the radius of curvature and the diameter of the hole inlet or exit as well as the relative needle seat angle. The steepest descent method has been used to drive the calculated gradients to zero and update the design parameters. For the validation of the model two representative inverse design cases have been selected. Studies showing the behaviour of the model according to different numerical and optimisation parameters are also presented. For the purpose of optimising the geometries, a cost function intended to maximise the discharge coefficient was defined. At the same time it serves the purpose of restructuring geometries which have controlled or eliminated cavitation inception in the hole entrance. This is identified in the steady-state mode by reduction of the volume of negative relative pressure appearing in the hole entrance. Results of cavitation control on some representative nozzle geometries show significant benefits gained by the use of the developed method. This is mainly because the developed model performs optimisation on numerous parametric combinations automatically. Results showed that, by using the proposed method, geometries with larger Cd values can be achieved and the cavitation inception can, in some cases, be completely eliminated. Cases where all the parameters were combined for redesign the geometry required less modification to predict larger Cd values than cases where each parameter was modified individually. This is an important result since manufacturers are seeking improvement in the performance of products resulting from the least geometry modifications.
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Bagy, Simon. "Design and optimization of aircraft engine nozzles in under-wing configuration." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS022.
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Lorsque les moteurs aéronautiques sont installés sous les ailes des aéronefs, des interactions aérodynamiques apparaissent entre l’ensemble propulsif et la voilure, qui sont aussi appelées « effets d’installation ». L’augmentation du taux de dilution des turbofan, permettant de réduire leur consommation de carburant, conduit à des diamètres de nacelles plus importants qu’auparavant, et renforce ces phénomènes. En particulier, l’arrière-corps et les tuyères du moteur sont situés à proximité de l’intrados de la voilure et sont fortement impactés par ces interactions aérodynamiques. Afin de mieux prendre en compte les effets d’installation dès les phases préliminaires de conception, cette thèse vise à développer des méthodes pour le dessin des lignes aérodynamiques de tuyères basées sur des optimisations de formes, s’appuyant sur des outils de dessin industriel (CAO) et des simulations aéro-propulsives couplées. Les modèles géométriques industriels utilisent généralement des logiciels commerciaux de CAO, et comprennent des centaines de paramètres de dessin. Cependant, une étude bibliographique montre que les méthodes d’optimisation existantes ne permettent pas de traiter des cas avec un grand nombre de variables tout en incluant des logiciels commerciaux en « boîte noire ». En réponse à cette difficulté, une méthode originale, appelée combinaison convexe, est proposée et développée dans ce travail. En se servant du savoir-faire industriel pour définir un sous-espace de l’espace de conception, cette approche innovante permet de réduire la dimension du problème d’optimisation. Ainsi, elle donne accès à la plupart des méthodes d’optimisation pour la recherche d’un optimum sur l’espace réduit. Tout d’abord, cette approche a été appliquée à une nacelle de moteur mono-flux et bidimensionnelle. Sur ce cas simple, sans CAO, la méthode a été testée et validée. De surcroît, explorer l’espace réduit s’est avéré être une stratégie parfois plus performante que l’exploration du domaine de design complet. Puis, un cas de nacelle double-flux de complexité industrielle a été mis en œuvre, avec des géométries CAO. Les optimisations opérées sur cette nacelle isolée (sans présence de l’avion) ont permis de démontrer le bon fonctionnement de la méthode avec des outils industriels de conception. Pour finir, des travaux ont été menés pour développer des calculs aérodynamiques comprenant un couplage avec un modèle thermodynamique de moteur, aussi appelés simulations couplées aéro-propulsives. A terme, de tels calculs pourront être intégrés au sein de la chaîne d’optimisation. Les travaux de thèse ont donc consisté à mettre en place un processus d’optimisation aérodynamique adapté pour le dessin de tuyères de moteurs aéronautiques, tout en prenant en compte les outils de conception et des cas d’application industriels. Bien que l’application à une configuration motrice installée avec couplage aéro-propulsif n’ait pas été effectuée dans le cadre de cette thèse, l’approche développée permettra sa mise en œuvre industrielle dans un futur procheWhen aircraft have under-wing propulsion systems, aerodynamic interactions appear between engines and wings. The trend of increasing turbofans by-pass ratio in order to improve their efficiency leads to greater engine diameters, and therefore strengthens these installation effects. In particular, the engine rear-body and the nozzles are located in the vicinity of the wing pressure side and are directly concerned by these interactions. In order to take these effects into account during early design phases of nozzles aerolines, the present thesis work aims at developing design approaches based on aerodynamic shape optimization methods, with industrial tools (such as CAD) and coupled aeropropulsive simulations. Industrial geometrical models are usually defined with commercial CAD software and comprise hundreds of design parameters. However, a literature review on optimization methods shows the difficulty of considering these software as well as a high number of design variables. Consequently, an original approach called convex combination is proposed. This method enables a dimensional reduction for the optimization problem, by using industrial know-how to define a subspace of the design space. Thus, it allows the use of most optimization methods for optimum research on the subspace. At first, this approach is tested and validated on a 2D single-flow nozzle case. On this case without CAD, exploring a subspace appears capable of outperforming full-space research. Then, a case of industrial complexity is defined, with a CAD geometry of turbofan nacelle and dual separate flow nozzles. Optimizations performed on this isolated nacelle (without aircraft) validate the use of the proposed approach with industrial design tools. Finally, some developments towards fully-coupled aeropropulsive simulations are made. In the end, these simulations coupling aerodynamics to a thermodynamic engine model are expected to be integrated in the optimization workflow. The thesis work consisted in developing optimization strategies and workflows adapted to the design of aeronautic turbofan nozzles, while considering industrial use cases and tools. Although the final application case on a complete aircraft with under-wing engines has not been covered in this work, the proposed convex combination approach and the associated workflow will allow to carry out this study in the near future
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Paci, Paolo. "Monitoring vapor phase concentration in supersonic flows." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0428103-215650.
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Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: infrared spectroscopy; aerosols; nucleation; tunable diode laser; condensation; supersonic nozzles. Includes bibliographical references (p. 73-76).
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Haddad, A. "Supersonic nozzle design of arbitrary cross-section." Thesis, Cranfield University, 1988. http://hdl.handle.net/1826/3512.
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An investigation, both theoretical and experimental in nature, has
been undertaken to develop a simple method for the design of
supersonic nozzles and, indeed, inlets of quite complex shapes from
known or calculated axisymmetric flowfields.
1he axisymmetric flowfield is determined using a computer program
based on the method of characteristics. Streamlines are calculated by
direct integration of the axisymmetric stream function.
7he desired shape is chosen at the exit of the computed
axisymmetric nozzle having the desired length and Mach number. Its
describing points are then traced along the corresponding streamlines
back to the throat. Streamsheets formed by these streamlines define
the new shape.
Following this approach, two three-dimensional nozzles were
designed : one of elliptical cross-section and a two-dimensional
wedge. Flows within the two configurations were further simulated
using a general purpose three-dimensional CFD code, "PHOENICS", while
the elliptical nozzle was subsequently manufactured and submitted to
experimental tests.
Results from the experimental tests and three-dimensional
numerical simulation, as well as predictions of the performance of
the nonaxisymmetric nozzles and their axisymmetric counterparts were
obtained and compared.
Good agreement was achieved between the several components of the
study demonstrating that it is possible, using this relatively simple
method, to design satisfactory three-dimensional nozzles.
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Whidby, Jon Clark. "Precision machining of a turbine nozzle segment." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17306.
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Ramirez, Carlos. "Meso-machining of miniature space system components." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Hallenbeck, Kyle J. "Low Reynolds number water flow characteristics through rectangular micro diffusers/nozzles with a primary focus on major/minor pressure loss, static pressure recovery and flow separation." Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002391.
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Trejo, Adrian. "Impacting testing of high temperature ceramics through the use of a vitiated heater for hot and cold fire collisions." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Naik, Nisarga. "MEMS-based nozzles and templates for the fabrication of engineered tissue constructs." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42853.
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This dissertation presents the application of MEMS-based approaches for the construction of engineered tissue substitutes. MEMS technology can offer the physical scale, resolution, and organization necessary for mimicking native tissue architecture. Micromachined nozzles and templates were explored for the fabrication of acellular, biomimetic collagenous fibrous scaffolds, microvascular tissue structures, and the combination of these structures with cell-based therapeutics. The influence of the microstructure of the tissue constructs on their macro-scale characteristics was investigated.