Comparison of predicted and experimental external heat transfer around a film cooled cylinder in crossflow

Calculations were made of the film cooling provided by rows of holes around the circumference of a cylinder in crossflow and the results were compared to experimental data. The calculations and experimental data were for conditions that simulate most of those that are typical of air cooled turbine vane leading edges. Injection was from a single and multiple rows of holes located at different angular locations from the stagnation line. The holes in the rows were angled normal to the flow direction and at a 25 degree angle to the cylinder wall. The calculations and experimental data were for several constant values of blowing ratios for all rows and for different blowing ratios for each row, representing a simulation of a common coolant plenum supply to multiple rows of holes. The calculations were made using a finite difference boundary layer code, STAN5. Contrary to initial expectations that injection would trip the boundary layer flow into the turbulent regime, the results indicated that the high free stream acceleration apparently kept the flow laminar for holes in the first 45 degrees past stagnation. The trend in Stanton number reduction due to coolant injection was predicted with generally good agreement at the lower blowing rates, but for multile rows of holes, agreement was poor beyond the first row

Transitioning from recruit to officer : An investigation of how stress appraisal, and coping influence engagement

This study investigated stress, coping, and work engagement among Portuguese police officers while undergoing academy training and then 1 year later, when on duty. It was hypothesized that stress appraisal and coping preferences predicted engagement. Additionally, in order to test a full cross‐lagged prediction model, it was hypothesized that stress, coping, and engagement in recruits predicted these variables later when working as police officers. Structural equation modeling was used to test the research hypotheses. Results suggest that coping and stress appraisals do not seem to be strong predictors of work engagement among recruits and police officers on duty. With the exception of self‐blame, that seems to be a strong predictor of work engagement among police officers on duty. These results highlight the need to investigate other potential variables such as working conditions that may better explain work engagement. Considering the positive influence of engagement on health, wellbeing, and performance of police recruits and officers future applied and theoretical implications are discussed.Fundação para a Ciência e a Tecnologia - FCT; FEDERinfo:eu-repo/semantics/acceptedVersio