Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-91).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 87-89). Also available on the World Wide Web.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (M.S.)--Ohio State University, 1986. / Includes bibliographical references (leaf 149). Available online via OhioLINK's ETD Center

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.

Dust control is a very significant issue in underground coal mining. The benefits of reducing dust levels will be a lesser risk of lung disease to coal miners, improved working conditions and a reduced risk of dust explosions. Coal dust is commonly suppressed by water sprays but suppression efficiency is not high because dust tends to travel in the air flow round the water droplets rather than being captured by them. If water sprays are electrostatically charged, then a significant improvement in dust suppression efficiency may be achieved. Of the three principal droplet charging mechanisms, i.e. corona charging, induction charging and contact charging, corona charging is the most widely used in many industrial fields including dust suppression, However, it requires a high applied voltage, ranging from thousands to more than a hundred thousand volts, depending on the geometry of the charging equipment. Induction charging has been used in agricultural spraying since Law (1978) developed an embedded-electrode induction charging spraying nozzle. This nozzle provides a compact, inexpensively fabricated droplet charger and, reduces design requirements on size and output voltage (of the order of 1000 volts). It also reduces the potential for mechanical damage, misalignment and personnel hazard. In order to evaluate the effectiveness of dust suppression, either the charge on individual droplets or the charge-to-mass ratio of water sprays needs to be known. However, the parameters which control the charge applied to water and the charging rate have been unsolved theoretically for any charging mechanism. The existing theories for the induction-charged and air-atomising a liquid jet have been found to be inadequate. And there is no theory available for corona charging of the droplets produced with a pneumatic nozzle in order to predict the spray charge level or the spray charge-to-mass ratio. In view of this situation, mathematical models have been developed in this thesis for both the corona and induction charging mechanisms. During the development of the theories, it has been assumed that for corona charging, that the jet is disintegrated into droplets and the droplets are then charged; for induction charging, that the jet is first charged and the charged jet is then disintegrated into charged droplets. The Sauter mean diameter of the sprays, D32 , plays an important role in linking the individual droplet charge to the spray charge-to-mass ratio for both charging mechanisms. The developed theories are general models suitable for any liquid with both corona and induction charging. Theoretical calculations for the spray charge-to-mass ratio, individual droplet charge and the ratio of droplet charge to the Rayleigh charge limit have been presented for almost all of the influencing electrical and mechanical parameters such as applied voltage, air flowrate, liquid flowrate, liquid conductivity, liquid dielectric constant, nozzle dimensions, cylindrical electrode dimensions, and fluid parameters, for example, density, viscosity and surface tension. In the calculation for corona charging of droplets, the effect of the droplets on corona current and corona-onset voltage has been assessed for first time. The introduction of the Sauter mean diameter of the sprays, D32 , makes the assessment possible. Theoretical calculations for induction charging of liquid jets have shown that provided liquids have a conductivity value higher than the critical value, s = - 10 4 S/m, then they can be charged satisfactorily by the induction charging method. Among all of the influencing parameters, the electrical and mechanical parameters determine the charging rate and the water spray charge level. The suitability of employing these two charging mechanisms to dust suppression in coal mine has been evaluated based on the spray charge level, safety issues and the simplicity or otherwise of the equipment. The induction charging method was considered to have advantages over its corona charging counterpart, and has been chosen for charging the water sprays in the experiment program. Water has a conductivity of s = - 10 2 S/m, higher than the critical value, s = - 10 4 S/m. Based upon theoretical considerations, it is concluded that water is an appropriate liquid for corona charging, based on its dielectric constant, and for induction charging, based on its conductivity. In order to facilitate the testing of electrostatically charged water spray cloud parameters, a spray charger/collector was designed and constructed by others and a computerised data acquisition system has been employed. According to the theory developed for induction charging, the optimum length of the charging electrode has been analysed based upon the assumption that water jet is first charged and then the charged jet is disintegrated into charged droplets by the high pressure air. An experimental program examined the dependence of spray current upon four parameters: air flowrate, water flowrate, applied voltage and jet diameter. The experiments have shown that the induction-charged air-atomising nozzle used in the experiment is able to impart a significant charge into the water sprays. The spray charge-to-mass ratio calculated based upon the measured spray current demonstrates the same characteristics as predicted by theory: increasing with air flowrate, decreasing with water flowrate, increasing with applied voltage to a peak value then decreasing with further increase in the voltage, and increasing with jet diameter. A successful interpretation of an important phenomenon in the inductioncharged air-atomising a water jet, that spray charge-to-mass ratio and spray current increase with air pressure (or air flowrate) and decrease with increasing water flowrate, has been achieved based on the theories developed in this thesis. This phenomenon occurs because increasing air flowrate and/or decreasing water flowrate leads to a higher velocity of jet flowing through the induction electrode. However, when water flowrate becomes very small, a decrease in spray current with increasing air pressure (or flowrate) may be caused both by jet breakup inside the electrode and by contraction of the jet. In order to verify the theory, a preliminary comparison of experimental data with theoretical predictions employing a constant kic in the air-jet interaction coefficient a which was assumed to be 0.7 has shown a general agreement. However, the value of kic appears to be related to jet diameter, air/water mass ratio and applied voltage. An empirical equation for kic has then been formulated based on the experimental data for the spray charge-to-mass ratio. Finally a comparison of experimental results with theoretical predictions using the formulated kic shows an improved agreement. It is concluded that the induction-charged air-atomising nozzle has a potential application in dust suppression in coal mines, as the voltage required to charge water sprays is only 1000 ~ 1200 volts, and that the theory developed for induction charging of water sprays can be used to guide laboratory investigations and design processes for dust suppression and other industrial applications which might employ the electrostatic charging of liquid sprays.

Droplet formation from a rigid and a vibration nozzle driven by a pulsing pressure is simulated. Droplet formation is simulated by using one-dimensional model. For the case of droplet formation from a vibration nozzle, the nozzle vibration is simulated by large deflection plate vibration equation. Droplet formation from a rigid nozzle is studied simply by setting the nozzle deflection always to be zero. The one-dimensional model is solved by MacCormack method. The large deflection plate vibration equation is solved by mode shape approximation and Runga--Kuta time integration method. Three different effect factors, the driving pressure thrust input effects, the fluid viscosity effects, and the nozzle vibration effects, on droplet formation are studied. The driving pressure thrust input effects and the fluid viscosity effects are studied based on a rigid nozzle. The nozzle vibration effects are studied by comparing the results from a vibration nozzle with the results from a rigid nozzle. Results show: 1) the primary droplet break-off time is constant if the driving pressure magnitude is high, but the primary droplet volume and primary droplet velocity increase slightly as the driving pressure thrust input increase; 2) higher thrust input can possibly result in the occurrence of overturn phenomenon; 3) increasing the fluid viscosity cause the primary droplet break-off later, but the primary droplet volume and the primary droplet velocity does not change significantly by fluid viscosity; 4) the nozzle vibration effect on the primary droplet break-off time and the primary droplet size is small, but the nozzle vibration cause the primary droplet velocity to increase by an amount of the nozzle vibration velocity magnitude; 5) nozzle vibration cause longer liquid thread to form and the total satellite droplet volume to increase significantly which eventually break into multiple satellite droplet. / Graduation date: 2004

Thesis (Ph. D.)--University of New South Wales, 2000. / Also available (in part) online.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: atomizing; spray cooling; thermal stress. Includes bibliographical references (p. 54).

DANTAS, Maria Jorgiana Ferreira. Avaliação de um sistema de aplicação de agrotóxicos na cultura do mamão: redução do risco de contaminação ambiental. 2010. 97 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2010. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-24T19:03:17Z No. of bitstreams: 1 2010_dis_mjfdantas.pdf: 11525819 bytes, checksum: 00e7bbc95e7ad099b7ea22ef3a71bf5b (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:19:48Z (GMT) No. of bitstreams: 1 2010_dis_mjfdantas.pdf: 11525819 bytes, checksum: 00e7bbc95e7ad099b7ea22ef3a71bf5b (MD5) / Made available in DSpace on 2016-07-21T20:19:48Z (GMT). No. of bitstreams: 1 2010_dis_mjfdantas.pdf: 11525819 bytes, checksum: 00e7bbc95e7ad099b7ea22ef3a71bf5b (MD5) Previous issue date: 2010 / O mamoeiro é uma cultura de grande expressão agrícola e a utilização de agrotóxicos nas lavouras é uma preocupação constante dos produtores. O objetivo deste trabalho foi avaliar um sistema de aplicação de agrotóxicos na cultura do mamão (Carica papaya L.) no Perímetro Irrigado Tabuleiro de Russas, CE. As avaliações do espectro e da deriva de calda foram feitas através da análise digital de gotas. A análise da deposição e das perdas foram realizadas por meio do método da condutividade elétrica das soluções obtidas após a lavagem das folhas de mamão (alvos) e o perfil de distribuição de calda aplicada nas diferentes alturas da cultura foi analisado utilizando-se uma mesa vertical de ensaios de campo. O experimento foi realizado em um lote agrícola situado no município de Russas – CE, com as seguintes coordenadas geográficas latitude 4º 57’ 44” S e longitude 23º 02’ 40” W. Foram utilizados como plantas de mamão Formosa, com espaçamento de 3 m entre fileiras e 2,5 m entre plantas. As aplicações foram efetuadas com um conjunto de pulverização tratorizado, constituído por um trator e um pulverizador turboatomizador ARBUS 2000. O experimento foi conduzido no delineamento inteiramente casualizado com quatro repetições, em esquema fatorial (3x2) + 1: três tipos de ponta de pulverização JA-1, JA-5 (jato cônico vazio) e TVI (jato cônico vazio com indução de ar) com duas diferentes pressões de trabalho (402 kPa e 1402 kPa) e a aplicação realizada pelo produtor, ponta J5-2 com pressão de 666 kPa (testemunha). Os dados foram submetidos à análise de variância e as médias discriminadas pelo teste de Tukey, a 5% de probabilidade empregando-se o software estatístico SAEG 9.0. Os resultados mostraram que, a ponta JA-1 com uma pressão de 1.402 kPa apresentou maior potencial de deriva e perdas de calda de 17% nas duas pressões analisadas. A ponta TVI com pressão de 402 kPa apresentou o menor potencial para deriva e perdas de 8,53 e 10,43% nas pressões de 1.402 e 402 kPa respectivamente. A ponta JA-5 nas duas pressões de trabalho testadas, apresentou valores médios de perdas de calda de 6%. As maiores perdas foram verificadas com a aplicação realizada pelo produtor com valores de 20,16%. Para as alturas estudadas a maior deriva foi nas alturas de 2,0; 2,5 e 4,0 m do que nas de 3,0 e 3,5 m. O aumento da pressão de pulverização aumentou a deriva, recomenda-se que para redução das perdas em uma aplicação utilizem-se pressões menores. A mesa vertical de ensaios de campo para aferição do equipamento de aplicação de agrotóxicos, mostrou-se eficiente. No geral todas as pulverizações depositaram menos calda nas regiões superiores da cultura do mamoeiro. Verificaram-se grandes perdas de agrotóxicos para o solo em todos os tratamentos aplicados. Há necessidade de se estudar em futuros trabalhos, a mesa vertical desenvolvida, para ajustar configurações dos bicos às condições específicas da cultura do mamoeiro, como também estudos referente às melhorias nos equipamentos de pulverização utilizados e desenvolvimento de novas técnicas para aplicação de agrotóxicos na cultura do mamão.