<p> This study deals with applied research in the field of environmentai noise problems, specifically the measuring of noise patterns near Mount Hope Airport originating from subsonic jet aircraft using the present runway facilities. Based on actual measurements the results have been analyzed and reduced to simple contour lines. </p> <p> An attempt has been made in this study to relate the concept of community noise in the vicinity of the airport to specific runway configurations, traffic density and patterns, and to provide a comparison between the noise levels due to the existing operations and those which may result due to the proposed expansion. Versatile computer programs have been developed in this study to simulate an airport model, compute and construct the noise contours for any combination of design requirements such as runway orientation, flight procedure, type of aircraft, etc </p> / Thesis / Master of Engineering (MEngr)

This thesis presents the results of steady, Reynolds-averaged Navier-Stokes (RANS) computations for jet flow emanating from a generic turbofan engine exhaust. All computations were performed with commercial solver FLUENT v6.2.16. Different turbulence models were evaluated. In addition to turbulence modeling issues, a parametric study was considered. Different modeling approaches for turbulent jet flows were explained in brief, with specific attention given to the Reynolds-averaged Navier-Stokes (RANS) method used for the calculations. First, a 2D ejector problem was solved to find out the most appropriate turbulence model and solver settings for the jet flow problem under consideration. Results of one equation Spalart-Allmaras, two-equation standart k-&amp / #949 / , realizable k-&amp / #949 / , k-&amp / #969 / and SST k-&amp / #969 / turbulence models were compared with the experimental data provided and also with the results of Yoder [21]. The results of SST k-&amp / #969 / and Spalart-Allmaras turbulence models show the best agreement with the experimental data. Discrepancy with the experimental data was observed at the initial growth region of the jet, but further downstream calculated results were closer to the measurements. Comparing the flow fields for these different turbulence models, it is seen that close to the onset of mixing section, turbulence dissipation was high for models other than SST k-&amp / #969 / and Spalart-Allmaras turbulence models. Higher levels of turbulent kinetic energy were present in the SST k-&amp / #969 / and Spalart-Allmaras turbulence models which yield better results compared to other turbulence models. The results of 2D ejector problem showed that turbulence model plays an important role to define the real physics of the problem. In the second study, analyses for a generic, subsonic, axisymmetric turbofan engine exhaust were performed. A grid sensitivity study with three different grid levels was done to determine grid dimensions of which solution does not change for the parametric study. Another turbulence model sensitivity study was performed for turbofan engine exhaust analysis to have a better understanding. In order to evaluate the results of different turbulence models, both turbulent and mean flow variables were compared. Even though turbulence models produced much different results for turbulent quantities, their effects on the mean flow field were not that much significant. For the parametric study, SST k-&amp / #969 / turbulence model was used. It is seen that boundary layer thickness effect becomes important in the jet flow close to the lips of the nozzles. At far downstream regions, it does not affect the flow field. For different turbulent intensities, no significant change occurred in both mean and turbulent flow fields.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The purpose of this work is to study and characterize aerodynamically a free jet operating at subsonic regime and identify its acoustic signature. This study aims to analyze fundamentally the turbulent structures and the total noise produced at different Mach numbers. This kind of research is crucial to the understanding of these mechanisms of noise generation and propagation, and it is extremely important for aeronautical applications, for instance, the jet engine exhaust. The research is done by analysing the data obtained in experiments using pitot tube, hot-wire anemometer and acoustic measurements. This work also describes the experimental procedures for each step of analysis, as well as the characteristics of jet noise facilities. The data from measurements with a pitot tube was used to study the mean velocity profiles. The average properties are also analyzed with an anemometry system, likewise used to study the turbulent intensity at eleven axial lines, ranging from the centerline to the edge of the nozzle (lipline). These results are compared with literature and has verified the accuracy of hot-wire anemometers for turbulent intensities lower than 15%. The aerodynamic data are obtained for Mach numbers 0.25, 0.50 and 0.75, from the nozzle exit to thirteen diameters in the direction of the jet. The acoustic study is carried out by analyzing the sound pressure level obtained at six positions in the far field, with observer angles ranging from 40 to 110º. In this campaign more velocities are studied with Mach numbers from 0.18 to 1.00 with step of 0.05 are described. A database with the sound pressure level as a function of frequency is constructed from this information. / O objetivo deste trabalho é estudar e caracterizar aerodinamicamente um jato livre operando em regime subsônico e identificar a assinatura acústica do mesmo. Esse estudo busca analisar fundamentalmente as estruturas turbulentas e o ruído total produzido em diferentes números de Mach. Tal estudo é crucial para o entendimento desses mecanismos de geração e propagação, e encontra extrema importância para aplicações aeronáuticas, como, por exemplo, a exaustão de motores a reação (jato). A investigação é feita através da análise dos dados obtidos em experimentos utilizando tubo de pitot, anemômetro de fio-quente e ensaios acústicos. Neste trabalho também são descritos os procedimentos experimentais de cada etapa de análise, bem como as características dos laboratórios utilizados para o estudo do ruído de jato. Com os dados provenientes das medições com tubo de pitot são estudados os perfis de velocidade média. As propriedades médias também são analisadas com o sistema de anemometria, que ainda é utilizado para estudo da intensidade turbulenta em onze linhas axiais, variando da linha de centro até a borda do bocal (lipline). Estes resultados são comparados com a literatura e é constatada a acurácia dos anemômetros de fio-quente para intensidades turbulentas menores que 15%. Os dados aerodinâmicos mencionados são obtidos para números de Mach 0,25, 0,50 e 0,75, a partir da saída do bocal até treze diâmetros na direção do jato. O estudo acústico é feito através da análise do nível de pressão sonora obtido em seis posições no campo distante, com ângulos de observação variando de 40 a 110º. Diferentes velocidades também foram analisadas, desta vez, com números de Mach de 0.18 a 1.00 com passo de 0.05. Um banco de dados com o nível de pressão sonora em função da frequência é construído a partir destas informações. / Mestre em Engenharia Mecânica