Mohd Radzi Abu Mansor

Characterization of Hydrogen Jet Development in an Argon Atmosphere

Characterization of the hydrogen-jet penetration in an argon atmosphere would first be analyzed in order to find the optimal condition for operating an argon-circulated hydrogen internal combustion engine. In this study, experiments were made in a constant-volume vessel to obtain the hydrogen-jet development data for different conditions of injection pressure, ambient pressure and nozzle diameter in argon and nitrogen atmospheres through observation using high-speed shadowgraph images. Experimental data were then compared with proposed momentum theory calculation in order to describe the development of hydrogen-jet penetration. From the result, α = 1.25 was used as an experimental constant. The momentum theory calculation is one of the main important data in helping to set the design parameters for jet penetration and to further established the operational conditions for an argon-circulated hydrogen engine.

Effect of Injector Nozzle Design on Spray Characteristics for Hydrogen Direct Injection Engine Conditions

Hydrogen has a unique flammability property compared to other fuels. Previous researches proved that direct injection is the most suitable method for this particular fuel. This research aims to study the effect of injector nozzle geometry on mixture and internal combustion efficiency in four stroke automotive engine which operates using hydrogen fuel. The research will concentrate on two aspects, namely the inflow and outflow profile of the injector nozzle. For each flow profile, the effect of geometrical design of the nozzle on the parameter such as flow velocity, fuel penetration distance, average mass fuel consumption and diffusion will be studied in detail. In this study, numerical simulation analysis was done by using the computing fluid dynamics (CFD) software, Star-CCM+. Models comprise of multiple orifice nozzle geometry with single angle orifice and double angle orifice was developed with CAD software. A suitable design for a better mixing nozzle would then be determined. Nozzle which possesses a high number of orifice and a smaller diameter will result in a higher flow velocity in the cavity nozzle channel. Geometry of nozzle with different angle of orifice was found to be the most suitable due to the low flow penetration distance and fuel consumption as well as combustion enhancement by the diffusion rate.

Study on Hydrogen-Jet Development in the Argon Atmosphere

Hydrogen is one of the promising energy carriers for the future because of its low polluting feature that can be used mainly in internal combustion engine. Since hydrogen combustion in the noble-gas and oxygen atmosphere forms only water, closed-cycle operations for a zero-emission and high-efficiency engine would be realized. In order to find the optimal condition of hydrogen injection in the argon circulated hydrogen engine, characterization of the hydrogen-jet penetration is required to be analyzed. In this study, experiments were made in a constant-volume vessel to investigate the hydrogen-jet developments for different conditions of injection pressure, ambient pressure and nozzle diameter in argon and nitrogen atmospheres. Also, high-speed shadowgraph images were observed at an individual case. Obtained data exhibit that the development of the hydrogen-jet in argon is slower than that in nitrogen due to its high density and faster at a higher injection pressure, at a lower ambient pressure and with a larger nozzle-orifice diameter. Characteristics of hydrogen jets were discussed through those fundamental data, which may help setting design parameters and controlling operational conditions in the argon circulated hydrogen engine.

Application of Taguchi method in optimization of design parameter for turbocharger vaned diffuser

Purpose The purpose of this study is to determine the best vaned diffuser design that can generate higher pressure output at a predetermined speed. Design/methodology/approach Several vaned diffusers of thin, flat-type design with different number of blades and blade angle were fabricated. The vaned diffusers were fitted inside the turbocharger compressor and test on a cold-flow turbocharger test rig. A Taguchi L27 orthogonal array is selected for analysis of the data. Influence of number of blades, blade angle and rotational speed on output pressure is studied using the analysis of variance (ANOVA) technique. Finally, confirmation tests are conducted to validate the experimental results. Findings The optimum design parameters of the vaned diffuser using signal-to-noise ratio analysis were six blades type, blade angle of 18° and rotational speed of 70,000 rpm. Results from ANOVA showed that the speed has the highest influence on output pressure. The number of blades and blade angle produced the least effect on the pressure output. Originality/value The study used the turbocharger with the impeller size 60 mm and adapted vaned diffuser to increase the output pressure.

Skin Friction Coefficient and Boundary Layer Trend on UKM Aster i-Bond

This study concerns with aerodynamic drag on a passenger car. By using computational fluid dynamics (CFD) method, we found that values of skin friction coefficients for three different parts of the car: front, top and rear parts, are different. This study addresses three different basic possible flows around a car: favourable, zero and adverse pressure gradients. Generally, cars use approximately 20% of their engine power to overcome aerodynamic drag, which is generally proportional to the frontal area. The boundary layer at each position has been analyzed to ascertain the effect of wall shear stress on the car surface. It is found that the value of wall shear stress velocity is highest at the rear part, followed by front and top parts. Subsequently, it is shown that the front part has the thinnest viscous region despite not being the part with the highest local ambient velocity compared with the top and rear parts. Despite its supposed aerodynamic shape, the rear part of the car sees separation of flow and the total drag per unit area here is the largest, twice as large as front part and more than seven times larger than the top part.

Aerodynamics Performance of Endwall Film Cooling under the Influence of Purge Flow in High Pressure Turbine Cascade

Modern gas turbine requires sophisticated cooling technologies to avoid thermal failure due to the extreme operating environment. Film cooling is one of the most important cooling technologies used for gas turbine hot-section components, particularly for blade aerofoil surfaces and endwall. Previous research has shown that the endwall region is considerably more difficult to cool than the blade aerofoil surfaces because of the existence of complex secondary flow structures such as horse-shoe vortex, cross flow and passage vortex in the blade passage. Therefore, this study focuses on aerodynamics interaction of the cooling air through the upstream slot with the secondary flow field. Experiments carried out using 5-holes Pitot tube have revealed the secondary flow field at blade downstream of linear cascade of high pressure turbine. A baseline condition without any leakage flows was compared with the leakage ejection case. Finally, both cases were validated by simulations from commercial software, ANSYS CFX.

Public Perception and Acceptance of Diesel-Powered Passenger Cars in Malaysia: An Initial Study

Globally, the transport sector consumes the biggest share of the fuel supply. Common fuels used in the transport sector are petrol and diesel. Diesel engines have been proven to be more advantageous over gasoline engines, in the aspects of fuel efficiency and engine reliability. The use of diesel passenger cars is very popular in European countries compared to Malaysia. A wider use of diesel-powered cars in Malaysia may benefit the car users, government and the country. The study of the causes of the low percentage of diesel-powered car usage in Malaysia was examined in this present study by using the latest data available in the literature, and by conducting a survey to measure the perceptions and views of the Malaysian public towards diesel-powered passenger cars. Results of this study showed that most of the respondents admitted that diesel engines give more savings. However, respondent perception that diesel-powered cars emit noise and high air pollution of the environment is the main reason Malaysians not choosing diesel-powered cars.