Direct Simulation Monte Carlo Analysis on Thrust Vectoring of a Supersonic Micro Nozzle using Bypass Mass Injection

Converging diverging micro nozzle is fundamentally intended for flow acceleration through the generation of kinetic energy for the advanced micro-propulsion systems. Such supersonic micro nozzles have significant applications in the launching, propulsion and rapid directional control of the micro-satellites for a better maneuver. Micro scale analysis of such flow devices is extended to the rarefied flow regime. Present study has addressed thrust vectoring in a planar converging-diverging supersonic micro nozzle by the bypass mass injection technique. Direct Simulation Monte Carlo (DSMC) method has been used for numerical modelling. Primary focus is given on the thrust vectoring control of the micro nozzle with a throat height of 20 micro meter and an expansion ratio of 1.7. For the secondary injection, a rectangular channel of 5 different bypass widths (2 - 12 micro meter) is considered for two different outlet pressures (Pout = 10 kPa and 40 kPa) while keeping the inlet pressure (Pin) and temperature (Tin) fixed at 1 atm and 300 k respectively. The physical behavior of the micro nozzle is acknowledged through the analysis of Mach, pressure, temperature and density contours. Numerical results reveal that the secondary flow injection is adapted into the primary flow through the formation of a pressure bump in the diverging section. Moreover, the total mass flow rate, secondary flow percentage, thrust force, the thrust coefficient and specific impulse increase with the bypass channel width. A change in thrust direction is obtained which in turn produces a considerable vectoring effect in the supersonic micro nozzle. The vectoring angle for Pout of 40 kPa peaks at 6 micro meter bypass channel whereas a gradual increase of the vectoring angle with the bypass channel width is observed for Pout = 10 kPa.Comment: Journal paper and it's under revie

Impacts of climatic disasters in the coastal area of Bangladesh : 'climate service' a way forward

This chapter considers ‘climate service’ as a tool to mitigate likely impacts of climatic disasters of the coastal regions in the southwest Bangladesh. Climate service enables to undertake the required development and capacity building for the coastal communities, who have the high potentiality of severe consequences of ecological disasters such as cyclones, flooding, sea levels rising and heat waves. The mitigation of adverse impacts of climatic disasters requires both comprehensive and appropriate plans and policies at national and regional level. In this chapter,we utilise life story interviews in the coastal area of Dacope sub-distrct under the division of Khulna, Bangladesh. The study analyses national and local development policies and plans to mitigate the impacts of climatic disasters in Bangladesh. Our study primarily explores the shortcomings of the national and local policies and plans to consider and apply climate service for mitigating the possible impacts of climate disasters. Our findings suggest that the current national and local development policies and plans insufficiently integrate climate service in undertaking the necessary developments and capacity building for risk reduction of climate disaster. Such inadequacies have significant impacts on the mitigation of the impacts of climate disaster. The outcome of the research will be instrumental for understanding and encouraging the stakeholders to integrate climate service in the national and local development policies and plans