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Software in the Context of the System
Published in Leanna Rierson, Developing Safety-Critical Software, 2017
An aircraft is a large system comprising multiple systems—it is essentially a system of systems. Aircraft systems can include navigation, communication, landing gear, flight control, displays, collision avoidance, environmental control, in-flight entertainment, electrical power, engine control, ground steering, thrust reversers, fuel, air data, and more. Each system has an effect on the overall operation of the aircraft. Obviously, some have more safety impact than others. Because of this, the civil aviation regulations and supporting advisory material classify failure categories according to risk. Five failure condition categories are used: catastrophic, hazardous/severe-major, major, minor, and no effect (these categories are discussed in Chapter 3). Each function in each system, as well as the combination of functionality, is assessed for its overall impact on safe aircraft operation. The aircraft operation includes multiple phases, such as, taxi, take-off, climb, cruise, descent, and landing. System safety is evaluated for each phase, as the effects of failure conditions can vary greatly, depending on the phase.
Irradiation Target Cooling Using Circular/Slot Air Jet
Published in Heat Transfer Engineering, 2019
Perumal Selvaraj, Kumaresan Natesan, Karuppanna Velusamy, Thirumalachari Sundararajan
Single or arrays of impinging jets are used to enhance convection heating or cooling. This technique has many applications like tempering of glass plate, metal sheets annealing, drying of textile and paper products, cooling of components in gas turbine engines and deicing of aircraft systems [1]. A number of authors experimentally and numerically studied various aspects of jet impingement heat transfer: jet Reynolds number from low to high, jet height to jet diameter, radial distance, Prandtl number, effect of entrainment on heat transfer, effect of temperature difference between jet and ambient air, cross flow, effect of confinement, angle of jet impingement, jet impingement over a flat surface and curved surface, effect of mesh screen in front of jet nozzle, effect of staggered array and inline array of impinging jets and also effects of nozzle shapes [2]–[16]. A detailed review of heat and mass transfer between impinging gas jets and solid surfaces is carried out by Martin [17]. In this paper, the empirical correlation proposed by Martin for array of circular nozzles is compared with the experimental results. Further the optimum jet configuration is evaluated by means of numerical tools and the optimum configurations were demonstrated by experiments with air as cooling medium.