81 research outputs found
Istihsan (juristic preference) : the forgotten principle of Islamic law
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Comparative analysis of alternative fuels in detonation combustion
No full textDetonation combustion prominently exhibits high thermodynamic efficiency which leads to better performance. As compared to the conventionally used isobaric heat addition in a Brayton cycle combustor, detonation uses a novel isochoric Humphrey cycle which utilises shocks and detonation waves to provide pressure-rise combustion. Such unsteady combustion has already been explored in wave rotor, pulse detonation engine and rotating detonation engine configurations as alternative technologies for the next generation of the aerospace propulsion systems. However, in addition to the better performance that the detonation mode of combustion offers, it is crucial to observe the environmental concerns as well. Therefore, this paper presents a one-dimensional numerical analysis for alternative fuels: Jet-A, Acetylene, Jatropha Bio-synthetic Paraffinic Kerosene, Camelina Bio-synthetic Paraffinic Kerosene, Algae Biofuel, and Microalgae Biofuel under detonation combustion conditions. For simplicity, the analysis is modelled using an open tube geometry. The analysis employs the Rankine-Hugoniot Equation, Rayleigh Line Equation, and Zel’dovich–von Neumann–Doering model and takes into account species mole, mass fraction, and
enthalpies-of-formation of the reactants. Initially, minimum conditions for the detonation of each fuel are determined. Pressure, temperature, and density ratios at each stage of the combustion tube for different types of fuel are then explored systematically. Finally, the
influence of different initial conditions is numerically examined to make a comparison for these fuels
Investigation of three-shaft high-bypass-ratio engine performance and emission prediction using alternative fuels
No full textProtecting the environment has become the main challenge in recent years specifically in aviation industries as they lead to the vulnerable energy crisis and simultaneously pose environmental concerns. With the stringent policies and legislations applied, many potential technological advancement programs are well planned and found out drop-in alternative fuels can potentially help to meet the target. In response, the purpose of this research aims to numerically evaluate the feasibility of the alternative fuels in terms of performance for a conventional aero-gas turbine engine. The investigated contents encompass the evaluation of engine performance analysis and emission prediction analysis. This research served as an extension of the PhD work of the principle investigator. Engine performance analysis utilizes a Cranfield Univeristy in-house latest code version of PYTHIA for modeling a three-shaft high-bypass-ratio engine which is similar to RB211 variant at various off-design conditions. Focusing on NOx formation, the emission analysis was also carried out using a Cranfield University in-house HEPHAESTUS emission model prediction. Alternative fuels are expected to show much better engine performance with further reductions in NOx emission. Finally, the research brings together all the analyses and makes trade-offs assessment between the performance and emission by applying a Design of Experiment (DoE) method, to identify the factors main effects, their interactions and the best trade-off solutions
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