Effective end wall profiling rules for a highly loaded compressor cascade

This paper presents a numerical study of a linear compressor cascade to investigate the effective end wall profiling rules for highly-loaded axial compressors. The first step in the research applies a correlation analysis for the different flow field parameters by a data mining over 600 profiling samples to quantify how variations of loss, secondary flow and passage vortex interact with each other under the influence of a profiled end wall. The result identifies the dominant role of corner separation for control of total pressure loss, providing a principle that only in the flow field with serious corner separation does the does the profiled end wall change total pressure loss, secondary flow and passage vortex in the same direction. Then in the second step, a multi-objective optimization of a profiled end wall is performed to reduce loss at design point and near stall point. The development of effective end wall profiling rules is based on the manner of secondary flow control rather than the geometry features of the end wall. Using the optimum end wall cases from the Pareto front, a quantitative tool for analyzing secondary flow control is employed. The driving force induced by a profiled end wall on different regions of end wall flow are subjected to a detailed analysis and identified for their positive/negative influences in relieving corner separation, from which the effective profiling rules are further confirmed. It is found that the profiling rules on a cascade show distinct differences at design point and near stall point, thus loss control of different operating points is generally independent.

No second chance: junior neonatal nurses' experiences of caring for babies at the end-of-life and their families

Death of an infant is acutely stressful for parents and professionals. Little is known about junior nurses' experiences providing end-of-life care in Neonatal units (NNU). This study aimed to better understand junior nurses' experiences providing end-of-life care in NNU. Neonatal nurses (n = 12) with less than 3 years experience participated in a focus group. Nominal Group Technique (NGT) was used to build consensus around the challenges faced, alongside suggested developments in improving future care provision. Primary analysis involved successive rounds of ranking and decision-making whilst secondary analysis involved thematic analysis. All issues, whether environmental, professional or social appeared driven by an awareness on the part of nurses, that there was no ‘second chance’ which created a huge pressure to ‘get if right’ for the infants and families. Regarding future care 2 areas of improvement identified were ‘Education and Training’ and Support. This paper unpacks these findings making recommendations for practice.