Systematic experimentation was carried out on forced convection heat transfer apparatus under varying non-linear flow conditions to understand the energy transfer as heat, with the purpose of enhancing performance of numerous engineering applications. Plate orientations, types of enclosures (solid, meshed, perforated), flow velocity variations etc. are taken as governing parameters to effect convective heat transfer phenomenon which is perceived as deviations in value of heat transfer coefficient. RV zonal system is utilized to simplify the fundamental understanding of heat transfer coefficient variation with surface orientation under varying flow field. The objectives of this work are as follows: 1) To establish relative effectiveness of forced convective heat transfer under varying flow field. 2) To investigate the implications of varying shapes and sizes of perforations on confined forced convective heat transfer. To understand the controlling mechanism and role of key controlling parameters.

-Combustion in itself is a complex phenomenon that involves the interaction and interplay of multiple phenomena, the combined effect of which give rise to the common flame that we see and use in our daily life applications from cooking to propelling our vehicles to space. The least thing that goes unnoticed about these flames is the effect of the various phenomena from its surrounding environment that affects its behaviour and properties. These phenomena cause a variety of energy interactions that lead to various types of energy transformations which in turn affect the flame behaviour. This paper focuses on experimentally investigating the effect of one such phenomenon, which is the acoustics or sound energy on partially premixed flames. The subject in itself is extensively studied upon as thermo-acoustics globally, whereas the current work focuses on studying its effect on soot formation of partially premixed flames. The said effect is studied in this research work by the use of a butane as fuel, fitted with a nozzle that houses 3 arrays consisting of 4 holes each that are placed equidistant to each other for entraining air and the resulting flame is impinged with sound from two independent and similar sound sources that are placed equidistant from the centre of the nozzle. The entire process is systematically video graphed using a 60 fps regular CCD and analysed for variation in flame heights and flickering frequencies where the fuel mass flow rate is maintained constant and the configuration of entrainment holes and frequency of sound are varied, whilst maintaining constant ambient atmospheric conditions. The current work establishes significant outcomes on the effect of acoustics on soot formation; it is noteworthy that soot formation is the main cause of pollution and a major cause of inefficiency of current propulsion systems. This work is one of its kinds and its outcomes are widely applicable to commercial and domestic appliances that utilise combustion for energy generation or propulsion and help us understand them better, so that we can increase their efficiency and decrease pollution.

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The Combustion process in propulsion systems comprises of premixed flames and diffusion flames. As an active chemical propulsion system, the efficiency of operations depends significantly upon the type of combustion. In real cases, the transition of flames from one mode to another is noted in wide range of cases. This has necessitated research efforts to fundamentally understand the phenomenon for better combustion and thus better propulsion. The combustion transition from pre-mixed to the diffusion state is one of the least explored and quantitatively analysed domains. Present work, experimentally attempts to extensively study and quantify the physical causes thoroughly through manually induced transition in a butane-based cylinder fitted with a nozzle by using image processing techniques. The manually induced transition is processed by varying the inlet area for air entrainment. The phenomenon is systematically video-graphed and image segmentation is carried out to acquire the desired characters. These methods are implemented in unison to theoretically establish a non-dimensional parameter associated with the transition process and thus characterizing it. The results obtained from this experiment could be easily applied to liquid propellant-based propulsion systems for terrestrial and outer space utilities, where micro-gravity conditions play the cardinal role in combustion physics. Results acquired from the experiments are expected to be very helpful in application to space propulsion systems by yielding a prospective insight into the subject, leading to significant improvement in the efficiency and Eco-friendliness of existing propulsion systems.

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