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There have been concerted efforts towards improving the fuel efficiency of the jet engines in the past, with an aim of reducing the incomplete combustion. The process of combustion in a jet engine takes place in the combustor. A study was conducted for enhancement of air-fuel mixing process by computational analysis of an elliptically shaped combustor for a gas turbine engine. The results of computational analysis of an elliptical shape combustor were compared with a circular shape combustor used in gas turbine engines with a identical cross sectional area. The comparison of the computationally derived parameters of the two combustors i.e. temperature, pressure, and velocity are studied and analyzed. The study intends towards the comparison of the combustion efficiencies of the circular and elliptically shaped combustors. The combustion efficency of elliptical chamber is found to be 98.72% at the same time it was observed 56.26% in case of circular type combustor.

In recent decades due to the emerging use of composites, earlier metallic vessels have moved to composite overwrapped design. Even though the weight reduction is possible over earlier metallic vessels, various factors such as fluid-wall interaction, failure modes and effect of winding pattern in composite overwrapped pressure vessels need to be very seriously considered for getting a successful design. This paper provides a detailed review on various works carried by the researchers to evaluate the performance of composite overwrapped pressure vessels under various design and environmental factors. These variables include the geometry factors (size & shape of dome, length of cylindrical section), design factors (winding angle, winding thickness, thickness of the liner & overwrap, materials for liner & overwrap, interviewing), defects (notches, flaws), loading conditions (internal & external pressure, axial load, torsion, impact, fatigue, vibration) and the performance parameters (burst pressure, fatigue life, failure modes, leaks, deformations). [ABSTRACT FROM AUTHOR]

Mixing efficiency helps the thrust gain and jet noise reduction. Aerospace and aviation research communities around the world are constantly demanding cleaner, quieter and more efficient commercial aircrafts. Though there are many sources of noise during flight, one such is deficient mixing of air at the rear of the nozzle, uneven expansion of nozzle and corresponding engine noise is quite dominant. The mixing proficiency is achieved by mixing of cold air at the surroundings with the hot air that exits the nozzle. To reduce the engine noise, elliptical tabs are employed at the exit of convergent nozzle. These are passive noise controllers which create vortices to the outlet flow and entrain the cold mass from the surroundings in order to reduce the noise level. This paper is concerned with the various shapes and sizes of tabs to test the mixing efficiency at different Mach numbers. Further, mixing efficiency is evaluated by both qualitative and quantitative analysis of shadowgraph system and by employing a propitious pressure scanner. [ABSTRACT FROM AUTHOR]