The effect of superheat on the disruption of liquid droplets in a compressible gas flow was investigated experimentally in a small-scale, supersonic wind tunnel. Aerodynamically generated ethanol droplets of an average diameter of 0.1 mm were injected via a normal sonic jet into a Mach 1.8 freestream. Both nonsuperheated and superheated droplets were injected with initial Weber numbers of approximately 700. The droplets and flow structure were photographed using the shadowgraph method. The relatively high momentum of the liquid droplets typically caused them to pass out of the sonic jet structure. Nonsuperheated droplets showed no signs of disrupting after traveling over 200 mm downstream from the injection point. Only droplets with injection temperatures above the predicted boiling point at tunnel freestream static pressure (48°C) showed signs of disruption, typically after they left the sonic jet structure (30 to 100 mm downstream of the injection point). Droplets in this range of temperatures appeared to begin to boil from the downstream side of the droplet, shedding a vapor cloud before disrupting completely in the chaotic mode. Droplets with temperatures above the boiling point at the exit plane of the sonic jet began to disrupt in the chaotic mode almost instantly (within 1 exit nozzle diameter).

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Includes bibliographical references. / Sc.D.

Orientador: Dagoberto Martins / Banca: Carlos Gilberto Raetano / Banca: Edson Lazarini / Banca: Marcus Barifouse Matallo / Banca: Mario Sergio Tomazela / Resumo: Com o objetivo de quantificar os depósitos da calda de pulverização através de diferentes pontas e volumes de pulverização nos estádios V3 (3 folhas verdadeiras) e R1 (inicio da floração) de soja, foram conduzidos dois experimentos na área didática do Departamento de Produção Vegetal, pertencente à Faculdade de Ciências Agronômicas UNESP- Botucatu/SP. Cada experimento constitui-se nas cultivares CD 208 e CD 216 (crescimento determinado e indeterminado respectivamente) Os tratamentos avaliados foram: pontas de jato plano (AI 110015 a 150 L ha-1, AI 11002 a 200 e 250 L ha-1); pontas de jato plano duplo (TJ 60 11002 a 150, 200 e 250 L ha -1); pontas de jato cônico (TX-6 a 150, TX-8 a 200 e TX-10 a 250 L ha-1) e pontas de jato plano duplo e baixa deriva (DGTJ 110015 a 150 e DGTJ 11002 a 200 L ha-1), estas últimas avaliadas somente no estádio de R1. O delineamento utilizado foi de blocos ao acaso com quatro repetições. As aplicações foram realizadas com um pulverizador costal pressurizado a CO2, munido de barra com quatro pontas distanciadas de 0,5 m entre si, no momento em que cada cultivar alcançou os estádios V3 e R1. Para a avaliação da deposição foi utilizado na pulverização como traçador o corante Azul Brilhante 2 FD&C-1 (500 mg.L-1). De cada repetição foram coletadas 25 plantas, às quais foram adicionadas 100 ou 200 mL de água destilada para a extração do traçador , nos estádios V3 e R1, respectivamente. A determinação dos depósitos foi realizada por espectrofotometria e a leitura de absorbância no comprimento de onda de 630 nm. Os dados foram transformados em valores de depósitos por grama de massa seca e ajustados às curvas de regressão pelo modelo de Gompertz. O cálculo da moda foi realizado para determinar os valores de depósitos de máxima freqüência. Os resultados indicaram que a deposição... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to quantify spraying deposits in two soybean cultivars (208 CD and CD 216) at V3 stage (3 true leaves) and R1 stage (beginning of the budding) through different nozzles and volumes of spraying. For this purpose, two experiments, one with each cultivar, were conducted in the didactic area of the Agricultural Department, Agricultural College UNESP- Botucatu/SP consisting in eleven treatments: flatfan ( AI 110015 at 100 L ha-1, AI 11002 at 150 and 200 L ha-1); twin flat-fan nozzle (TJ 60 11002 at 150, 200 and 250 L ha -1); conical nozzle (TX-6 at 150, TX-8 at 200 and TX-10 at 250 L ha-1) and twin flat-fan and low drift nozzle (DGTJ 110015 at 150 and DGTJ 11002 at 200 L ha-1), these last ones only in the growth stadium of R1. The experimental design was randomized block, with four replicates. A CO2 - pressurized sprayer with a 0,5 m distance between nozzles was used. Deposition was evaluated by using 500 mg.L-1 of Brilliant Blue dye FD&C-1 in the spraying . At V3 and R1 grown stages, 25 plants were collected in each replication respectively, and by adding 100 and 200 mL of distilled water then courante was extracted. Deposited content was determined by spectrophotometry reading the absorbance at 4 630 nm wave length and data transformed into deposits per gram of dry matter. Gompertz model was used to adjust regression curves and ANOVA to determine deposits values of maximum frequency. Results indicated that deposition was superior at V3 stage for both cultivars being 2 and 3,5 superior than deposition at R1 for CD 208 and CD 216, respectively. In cultivar CD 208 at V3 stage, deposition was superior in treatments with the highest volume of 250 L.ha-1 independently the nozzle used and with the TX 8 nozzle using 200 L.ha-1 The higher variation between the unitary deposits was observed for the TJ nozzles with 150 and 200 L.ha-1 . At R1, all treatments except... (Complete abstract click electronic access below) / Doutor

O presente trabalho teve por objetivo avaliar e comparar dois sistemas de aplicação de agrotóxicos em citros visando à redução do volume de aplicação com base no estudo da quantidade de produto que permanece no alvo (deposição) e análise das gotas. Na citricultura utilizam-se altos volumes de aplicação (de 2000 a 5000 L.ha-1) para o controle de pragas e doenças incrementando os custos operacionais, por esse motivo, atualmente vem-se desenvolvendo diversos sistemas de aplicação com tecnologia sofisticada visando diminuir esses volumes para 200 ou 500 L.ha-1 mas permitindo que a quantidade de produto depositado no alvo seja eficaz no controle de pragas e doenças. Procuramos avaliar dois sistemas de aplicação de agrotóxicos com um pulverizador de jato transportado. Os sistemas de aplicação utilizaram os atomizadores rotativos de discos e os bicos hidráulicos para efeito comparativo do desempenho. Foi realizada uma pulverização em duas passadas para cada sistema sobre uma amostra de quatro árvores. Utilizaram-se papéis hidrosensíveis, folhas e placas de vidro para a coleta dos dados. Para a análise da gota utilizou-se o software de leitura visual e-Sprinkle e a análise de deposição foi realizada com cromatografia gasosa e cromatografia de permeação em gel. Concluiu-se que o sistema de aplicação com atomizadores rotativos mostrou resultados favoráveis de deposição quando comparado com o sistema de aplicação com bicos hidráulicos, uma vez que esses resultados não foram significativamente diferentes. O que resulta bastante importante é que o sistema de aplicação com atomizadores rotativos utilizou um quinto do volume de aplicação quando comparado ao sistema com bicos hidráulicos, pelo que se deve considerar de vital importância o aspecto econômico para trabalhos complementares. / The aim of the work was to evaluate and compare two application spray systems of pesticides in citrus, aiming the reduction of the application volume rate in based in the amount of product that remains in the target (spray deposition) and distribution of the drops. Actually in the citrus orchard high application volumes rates for the pest control are used increasing the operational costs. The application system must be based in sophisticated technology to reduce the application volumes rates and also be efficient in the pest control. For such we evaluated two pesticides application systems with an air carrier sprayer. The application systems used were the rotary discs atomizers and the hydraulic nozzles, to compare the performance based in the applied volume rates, spray deposition and droplets distribution. A spraying run for each system was performed on a random sample of four trees for each system, water-sensitive papers, leaves and glass slides had been used for data collection. The water-sensitive papers were analyzed with visual imaging software (e-Sprinkle) and the spray deposition was analyzed with gas chromatography and gel permeation chromatography. The application system with rotary discs atomizers used reduced application volumes rates and had less deposit than hydraulic nozzles but did not significantly differents. Those results were important because the application system with rotary discs atomizers only used fifth of the application volume rate compared with hydraulic nozzles, must be consider of vital importance the economical aspect to complementary works.

A tecnologia da aplicação tem papel fundamental na agricultura, pois proporciona uma correta aplicação do produto biologicamente ativo no alvo, ocasionando um melhor aproveitamento dos agrotóxicos. O objetivo do trabalho foi avaliar a influência de diferentes pontas e pressões na qualidade da pulverização na cultura do tomate por meio da quantificação do depósito e da cobertura foliar. Foram estudadas as pontas GA 11002 (jato plano com indução de ar), TTJ 60-11002 (jato plano duplo) e TT 11002 (jato plano padrão), todas nas pressões de 200, 350 e 500 kPa. Para todos os tratamentos a taxa de aplicação foi de 180 L ha-1. O percentual de cobertura foliar foi quantificado por meio da análise de imagens que detectaram o traçador fluorescente LRM 100 com o auxílio de luz ultravioleta. As imagens foram capturadas por uma câmera digital e processadas pelo software QUANT. O depósito foi quantificado pela extração e quantificação do traçador azul brilhante FD&C N°1 por meio de espectrofotometria. Para ambos os parâmetros foram analisadas amostras do estrato superior e inferior da planta. Houve diferença estatística somente para a cobertura foliar, sendo que na parte superior da planta a ponta de jato plano duplo apresentou menor cobertura na menor pressão. Nas maiores pressões houve um aumento da cobertura foliar favorecido pela formação de gotas médias e finas pelas pontas avaliadas. No estrato inferior a eficiência na cobertura foliar da ponta de jato plano diminui com o aumento da pressão. O depósito de pulverização foi favorecido pelo aumento da cobertura foliar. / The application technology plays a key role in agriculture as it provides a correct application of the product biologically active in the target, causing a better use of pesticides. The aim of this study was to evaluate the influence of different nozzles and spray pressures acting on tomato by quantifying the deposit and leaf coverage. Were studied the nozzles GA 11002 (flat fan air induction), TTJ 60-11002 (twin flat fan) and TT 11002 (standard flat fan), all pressures of 200, 350 and 500 kPa. For all treatments, the application rate was 180 L h-1. The percentage of leaf coverage was quantified by image analysis to detect the fluorescent tracer LRM 100 with the aid of ultraviolet light. The images were captured by a digital camera and processed by software QUANT. The deposit was quantified by extraction and quantification of tracer bright blue FD&C N° 1 by spectrophotometry. For both parameters were analyzed samples of top and bottom of the parts plant. Statistical difference only for leaf coverage, and at the top of the plant to twin flat fan nozzles showed lower coverage in less pressure. In the higher pressures there was an increase of leaf coverage favored by the formation of fine droplets medium and evaluated nozzles. In the bottom part plant coverage efficiency of foliar flat fan nozzles decreases with increasing pressure. The spray deposit was favored by increased leaf coverage.

A parametric study on Secondary Injection Thrust Vector Control (SITVC) has been accomplished numerically with the help of a commercial Computational Fluid Dynamics (CFD) code called FLUENT&reg / . This study consists of two parts / the first part includes the simulation of three dimensional flowfield inside a test case nozzle for the selection of parameters associated with both computational grid and the CFD solver such as mesh size, turbulence model accompanied with two different wall treatment approaches, and solver type. This part revealed that simulation of internal flowfield by a segregated solver with Realizable k-&amp / #949 / (Rke) turbulence model accompanied by enhanced wall treatment approach is accurate enough to resolve this kind of complex three dimensional fluid flow problems. In the second part a typical rocket nozzle with conical diverging section is picked for the parametric study on injection mass flow rate, injection location and injection angle. A test matrix is constructed / several numerical simulations are run to yield the assessment of performance of SITVC system. The results stated that for a nozzle with a small divergence angle, downstream injections with distances of 2.5-3.5 throat diameters from the nozzle throat lead to higher efficiencies over a certain range of total pressure ratios, i.e., mass flow rate ratios, upstream injections should be aligned more to the nozzle axis, i.e., higher injection angles, to prevent reflection of shock waves from the opposite wall and thus low efficiencies. Injection locations that are too much downstream may result reversed flows on nozzle exit.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: CFD; computational fluid dynamics; plume; nozzle; DSMC; numerical modelling. Includes bibliographical references (p. 83-86).

This thesis describes the commissioning and development of a pulsed supersonic nozzle, Fourier-transform microwave spectrometer and its application to the study of several weakly bound van der Waals complexes. A pulsed supersonic expansion, Fourier-transform microwave spectrometer based on the Flygare design with a number of modifications has been constructed with an operating range of 6-18 GHz. A homodyne detection circuit mixing signals to modulus values between dc and 1 MHz is used, requiring two measurements to determine absolute transition frequencies. Transition frequencies are measured from the power spectrum by determining the first derivative zero crossing point in a least squares fitting procedure. Semiautomation of many of the spectrometer operations has been achieved allowing unattended data collection over scans of up to 300 MHz. The microwave spectrum of Ar₂-OCS and Ar₂-OC³⁴S has been observed and analysed using conventional Watson S reduction hamiltonian parameters. Effective structural parameters are derived and used in a harmonic force field analysis, based on the centrifugal distortion constants, to compare the trimer interations with a model based on the sum of dimer interactions. A series of complexes containing the nitrogen molecule undergoing tunnelling motions have been studied. Hyperfine matrix elements for the first order nuclear quadrupole interaction are derived for the coupled identical nuclei case appropriate to the rapid tunnelling motions observed. The microwave spectrum of N₂-OCS is described. Tunnelling and nuclear spin statistical effects for two symmetry states are observed arising from the interchange of nitrogen nuclei. Rotational and quadrupole constants are derived; an accidental near degeneracy of two rotational levels allows the off-diagonal quadrupole coupling constant to be determined from second order effects. A tunnelling hamiltonian fitting the quadrupole coupling constants to an angular potential has been used to calculate the tunnelling frequency and barrier to N₂ rotation. The microwave spectrum of N₂-O₃ and a preliminary spectrum of N₂-SO₃ have been observed. Rotation-inversion motions of the O₃ and SO₂ moieties must be considered in addition to the N₂ tunnelling to fit the spectrum. Tunnelling frequencies for the O₃/SO₂ and geared motions with the N₂ are derived as well as structural parameters. Modifications for production of refractory molecules and complexes by laser ablation have been made. A modified nozzle employing rods of material is used with the ablation process taking place in the nozzle throat. Modifications to obtain an expansion along the axis of the microwave cavity employ a hemispherical Fabry-Perot cavity configuration. The system has been tested on a number of diatomic molecules including PbS and CuCl.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on June 11, 2009. "May 2009." "In partial fulfillment of the requirements for the degree [of] Master of Science in Agriculture with specialization in Plant Protection Science." "Presented to the faculty of California Polytechnic State University, San Luis Obispo." Major professor: Terry L. Vassey, Ph.D. Includes bibliographical references (p. 59-61). Also available on microfiche.

[pt] O 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. / [en] 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.