Use of surface heat transfer measurements as a flow separation diagnostic in a two dimensional reflected oblique shock/turbulent boundary layer interaction

The feasibility of using streamwise surface heat transfer measurements to detect the presence of flow separation in a two-dimensional reflected oblique shock/turbulent boundary layer interaction is reported. Surface heat transfer and static pressure data are presented for attached and separated flows for a free stream nominal Mach number range of 2.5 to 3.5 and shock generator angles of 2 to 8 degrees. The static pressure data do show the characteristic triple inflection point distribution for the strongly separated flow cases. The corresponding surface heat transfer data show unique trends that correlate well with the static pressure determination of the extent of the separated flow region. For the incipient or weakly separated flow cases, the static pressure data do not exhibit the characteristic triple inflection point distribution. However, the same trends in the heat transfer data that are seen for the strongly separated flow cases are evident for the weakly separated flows. Hence, the heat transfer data can be used to determine the extent of weakly separated flows when the surface static pressure distributions often can not

Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of shock wave/turbulent boundary layer interaction flows

The properties of 2-D shock wave/turbulent boundary layer interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique shock wave impingement on the turbulent boundary layer flow were considered. The oblique shock waves were induced with shock generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows

Proposta metodológica para avaliação de impacto e sustentabilidade em iniciativas agroflorestais de agricultores familiares e comunidades tradicionais.

O trabalho apresenta elementos metodológicos para a análise e monitoramento de iniciativas e intervenções agroflorestais adotadas por agricultores familiares e comunidades tradicionais, através de um conjunto de planilhas adaptadas a partir da composição da plataforma AMBITEC-AGRO, e da identificação de aspectos, indicadores e componentes sociais, ambientais e econômicos adequados às características destes grupos sociais. A análise da plataforma AMBITEC-AGRO e pré-validação de uma estrutura para avaliação de impacto e sustentabilidade resultou na geração de um conjunto de planilhas composto por três dimensões, 12 aspectos, 39 indicadores e 265 componentes. Após pré-validação realizada em oficinas metodológicas, a ferramenta está sendo validada em campo, junto a comunidades selecionadas nos estados do Pará e Maranhão. Informantes-chave definirão os indicadores e componentes para cada aspecto considerado e definirão os pesos relativos a serem atribuídos a aspectos, indicadores e componentes. Reuniões com grupos focais nas comunidades (definidos com base em características de gênero, geração, grupos de atividade e condição social) definirão fatores de ponderação a partir da percepção local sobre impacto/sustentabilidade de iniciativas locais e intervenções externas. O conjunto de resultados das reuniões com grupos focais permitirá gerar a ponderação de resultados para cada comunidade ou contexto analisado, e mapear discrepâncias internas

Forest use and agriculture in Ucayali, peruvian amazon: interactions among livelihood strategies, income and environmental outcomes.

Edited by Kanae Ishimaru and Shigeo Kobayashi

Community cohesion and distrust: tracing the roots of resource use and social equity in Maranhão, Brazil.

A comparative examination of trajectories of two communities in the Eastern Amazon experiencing land struggles in the 1980s sheds light on factors triggering their differential resource use patterns and contrasting ways in which social relations are manifested. While in one case community institutions were able enhance local livelihoods and residents? welfare, institutions regulating resource-use in the other case have failed to establish rules for a sustainable system. The examination of social relations over extended periods supports our understanding of today?s socioeconomic configurations in the two communities, and their interaction with the environment. Improved land-use planning is seen to require a state of affairs in which internal cooperation supersedes discord. Cooperation and agreement in one case, and discord and individual orientation in the other resulted from social facts that marked the communities during land occupation and subsequent state-supported land privatization. Processes examined reflected the contrast between a background of hierarchical, subordinated social relations, and a more egalitarian social structure. Today?s discrepancies in land-use trajectories and social life were traced back to attitudes and the agency of local residents as they confronted socio-structural and ecological opportunities and constraints in the past

A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields

The NASA Lewis Research Center Internal Fluid Mechanics Facility

An experimental facility specifically designed to investigate internal fluid duct flows is described. It is built in a modular fashion so that a variety of internal flow test hardware can be installed in the facility with minimal facility reconfiguration. The facility and test hardware interfaces are discussed along with design constraints of future test hardware. The plenum flow conditioning approach is also detailed. Available instrumentation and data acquisition capabilities are discussed. The incoming flow quality was documented over the current facility operating range. The incoming flow produces well behaved turbulent boundary layers with a uniform core. For the calibration duct used, the boundary layers approached 10 percent of the duct radius. Freestream turbulence levels at the various operating conditions varied from 0.64 to 0.69 percent of the average freestream velocity

Evaluation of a technique to generate artificially thickened boundary layers in supersonic and hypersonic flows

The feasibility of using a contoured honeycomb model to generate a thick boundary layer in high-speed, compressible flow was investigated. The contour of the honeycomb was tailored to selectively remove momentum in a minimum of streamwise distance to create an artificially thickened turbulent boundary layer. Three wind tunnel experiments were conducted to verify the concept. Results indicate that this technique is a viable concept, especially for high-speed inlet testing applications. In addition, the compactness of the honeycomb boundary layer simulator allows relatively easy integration into existing wind tunnel model hardware

Meios de vida, estratégias econômicas e dependência de recursos naturais em comunidades nas áreas de ocorrência de babaçuais.

A multiplicidade de estratégias econômicas adotadas em comunidades tradicionais e de agricultores familiares demonstra interações dinâmicas visando aumentar a resiliência de grupos vulneráveis. Neste artigo focalizamos situações em que produtos derivados da palmeira babaçu constituem fontes relevantes de sustento para comunidades no Maranhão. A renda média anual de 168 famílias em três comunidades atingiu R$7.234,00. Transferências sociais e trabalho assalariado representaram mais da metade da renda reportada pelos domicílios, enquanto produtos derivados do babaçu atingiram 12,5% da renda anual. Examinamos padrões de associação entre indicadores de renda, bem-estar, e dependência de atividades extrativas ou agrícolas. Adotamos uma tipologia de domicílios conforme estratégias econômicas, sendo a dependência definida por proporções relativas da renda agrícola e florestal/extrativa. A análise de variância indica diferenças estatisticamente significativas apenas entre domicílios com maior dependência de transferências sociais e trabalho assalariado, cuja renda anual é superior aos de orientação extrativista e diversificados