Statistical modelling for prediction of axis-switching in rectangular jets

Rectangular nozzles are increasingly used for modern military aircraft propulsion installations, including the roll nozzles on the F-35B vertical/short take-off and landing strike fighter. A peculiar phenomenon known as axis-switching is generally observed in such non-axisymmetric nozzle flows during which the jet spreads faster along the minor axis compared to the major axis. This might affect the under-wing stores and aircraft structure. A computational fluid dynamics study was performed to understand the effects of changing the upstream nozzle geometry on a rectangular free jet. A method is proposed, involving the formulation of an equation based upon a statistical model for a rectangular nozzle with an exit aspect ratio (ARe) of 4; the variables under consideration (for a constant nozzle pressure ratio (NPR)) being inlet aspect ratio (ARi) and length of the contraction section. The jet development was characterised using two parameters: location of the cross-over point (Xc) and the difference in the jet half-velocity widths along the major and minor axes (ΔB30). Based on the observed results, two statistical models were formulated for the prediction of axis-switching; the first model gives the location of the cross-over point, while the second model indicates the occurrence of axis-switching for the given configuration

Attitudes of ACES Members

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90239/1/j.1556-6978.1968.tb02048.x.pd

The Maine Economy—Through a Different Lens

William Knowles, a banker “from away” who has retired to Maine, gives his thoughts about the state’s economy, based on his reading, research, and conversations with a variety of Mainers. He structures his examination using four different “lenses,” which he terms: comparisons (how does Maine compare with other states and regions), cultivation (economic development), capital (especially human capital), and culture. Knowles challenges readers to think about whether Maine’s culture or belief system may be an important factor in restraining economic development

Exploratory Study of the Lived Experiences of Adoptees in The Caribbean

This qualitative research study offers exploration into Caribbean adoptee experiences related to their adoptive parent-child relationships. Existing studies focus on adoptive parent perspectives. Few accounts focus on Caribbean adoptees\u27 experiences with adoption (Caughman, 2007). The existing research serves a purpose by helping adopted parents discuss adoption with adoptees. However, this approach does not include thevoice of the adoptee and fails to encompass the totality of adoptee lived experiences. The research does not focus on the amplification of the adoptees\u27 voice, which in turn, neglects the adoptees\u27 role inunderstanding their family processes. Therefore, it is pertinent to include lived experiences of Caribbean adoptees in the adoptive phenomenon. This study aimed to find meaningful connections through curiosity-driven research. To highlight the idiosyncratic stories that encompass the Caribbean adoptees\u27 experiences, I used interpretative phenomenological analysis (IPA). Interviewing adults using narrative therapy as my conceptual framework provided rich descriptions into the meaning adoptees attach to adoptive family experiences. Study findings suggested that the marginalizing effects of the adoptee population, pressure to conform to cultural norms of family structure, and stigma surrounding retrieval of mental health services effect Caribbean adoptees overarching experience with adoption. Implications and future suggestions for this study will be provided and can be of use to all mental health professionals, persons providing child-centered services, and adoptive families that have hopes of advancing more collaborative adoptive outcomes

Reenvisioning Education for Civic Engagement in the Social Media Century

The reviewed article, “The Impact of Student Political Identity Over the Course of an Online Controversial Issue Discussion,” represents a timely response to the eye-opening influences of social media in modern political climates. Particularly, the project provides a useful model and relevant findings for future teachers and teacher educators to incorporate online political discussions. The study clearly demonstrates the value of online discussions, especially in mixed partisan groups. Based on the findings, three additional considerations were identified and elaborated on within this response. These include a renewed consideration of quantitative analysis, a focus of identity in civic education, and a recognition that schools are not politically neutral spaces

Mechanism of droplet-formation in a supersonic microfluidic spray device

Spray drying is an approach employed in automotive, food, and pharmaceutical industries as a robust and cost efficient liquid atomization technique offering direct control over droplet dimensions. The majority of commercially available spray nozzles are designed for large throughput spray drying applications or uniform surface coating, but microfluidic nebulizers have recently been developed as small scale alternatives. Here, we explore the physical parameters that define the droplet size and formation under supersonic flow conditions commonly found in microfluidic spray drying systems. We examined the spray nozzle operation using high speed imaging and laser scattering measurements, which allowed us to describe the spray regimes and droplet size distributions. It was determined that by using this spray nozzle device, droplets with diameters of 4–8 μm could be generated. Moreover, we show that the supersonic de Laval nozzle model can be used to predict the average droplet size. Our approach can be used as a platform for interfacing fluid microprocessing with gas phase detection and characterization

Active heat exchange system development for latent heat thermal energy storage

Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out