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Technical Paper

An Approach to Design an Air–Liquid Supersonic Ejector for Producing Aerosol Spray

This study aims to design a supersonic ejector, referred to as a liquid spray gun, with a simple operating procedure for producing an aerosol spray with adjustable droplet size distributions. A CFD model was developed to determine the influence of nozzle exit position and the primary air pressure on the supersonic patterns formed within the ejectors, providing a valuable insight into their internal physics. Based on the single-phase numerical results, at an air primary pressure of 2 bar, the flow may not reach a choking condition, possibly resulting in unstable ejector operation. However, at pressures exceeding 5 bar, the jet patterns emerging from the primary nozzle cause flow separation or the formation of vortex rings. This phenomenon leads to a flow configuration comparable to the diameter of the mixing tube, thereby reducing the available area for entrainment of suction flow.
Technical Paper

A New Design of Solid-State Bipolar Nanosecond Pulse High-Frequency Discharge Power Supply for Engine Ignition System

In this study, a bipolar nanosecond pulse all-solid-state power supply was developed including Lenz capacitance (LC) resonant circuit and full-bridge inverter circuit to provide plasma ignition mode for internal combustion engines. The power supply converts the direct current (DC) voltage into voltage pulses using the inverter circuit with insulated gate bipolar transistor (IGBT), and subsequently amplifies the voltage through a pulse transformer. In the magnetic compression circuit, two capacitors were utilized to store energy simultaneously and approximately double the voltage. By exploiting the hysteresis characteristics of the magnetic switch, a nanosecond pulse output was achieved. An enhanced full-bridge inverter snubber circuit was proposed, which can effectively absorb surge voltage, with a voltage impact reduction on the primary winding of the pulse transformer to less than 1%.
Technical Paper

Experimental and Numerical Investigations of a Dual-Fuel Hydrogen–Kerosene Engine for Sustainable General Aviation

Reducing CO2 emissions is an increasingly important issue. In aviation, approaches such as e-propulsion only represent a solution for special applications due to the low energy density of batteries. Because of the low-cost and robust design of combustion engines, this concept is still the most suitable for general aviation. For defossilization, besides e-fuels and bio-fuels, which represent the so-called sustainable aviation fuels (SAF), hydrogen can serve as a promising energy carrier for CO2 reduction. For this purpose, the combustion process of a dual-fuel hydrogen–kerosene (Jet A-1) engine was developed and investigated for use in small aircrafts. This study explores the influence of hydrogen addition on combustion parameters, emissions, and efficiency.
Technical Paper

Optimization of Hydroformed Exhaust Gas Recirculation Tube under Vibrational Load by Finite Element Analysis

This study emphasizes the importance of CAE approach in optimizing EGR tube under vibrational load. EGR tube is a weak link in the EGR system and chances of failure due to vibration and relative displacement of mating parts, i.e., overhang or improper support at exhaust manifold, intake manifold, or EGR system. Consideration of the mating parts for the EGR tube is very important to get the realistic resonance frequencies, otherwise it could have some different results in the CAE, which will deviate from the reality. So, it’s important to study the dynamic response on the EGR tube, which needs to be taken care during the design phase. This paper aims to optimize the EGR tube under vibrational load by using CAE techniques and the industry experience as a product expertise. some critical parameter such as damping is very important during the CAE, which can be generated by doing the rigorous testing and how it affects the stress and correspondingly FOS.
Journal Article

Engine Behavior Analysis on a Conventional Diesel Engine Powered with Blends of Lemon Grass Oil Biodiesel–Diesel Blends

Abstract Fossil fuel usage causes environmental pollution, and fuel depletion, further affecting a country’s economy. Biofuels and diesel-blended fuels are practical alternatives to sustain fossil fuels. This experimental study analyses lemongrass oil’s performance, emissions, and combustion characteristics after blending with diesel. Lemongrass oil is mixed with diesel at 10 (B10), 15 (B15), and 25% (B25) and evaluated using a 5.20 kW direct injection diesel engine. B10 brake thermal efficiency is 36.47%, which is higher than other blends. The B10 displays an 8.73% decrease in brake-specific fuel consumption compared to diesel. An increase in exhaust gas temperature for B10 than diesel is 4.5%. It indicates that higher lemongrass oil blends decrease exhaust gas temperature. The decrease in average carbon monoxide emissions in B10 to diesel is 22.19%. The decrease in hydrocarbon emissions for B10 to diesel is 7.14%.
Technical Paper

Transmission of Sound under the Influence of Various Environmental Conditions on Short Distances

Electric vehicles, being inherently quiet without the typical combustion noises, pose a potential safety concern, especially at low speeds. Consequently, an Acoustic Vehicle Alerting System (AVAS) is mandatory in many countries worldwide to warn pedestrians of approaching electric vehicles. The development of AVAS sounds involves conducting measurements on an outside noise test track to verify compliance with regulations. Various environmental parameters on the test track can influence the transmission of sound from the car’s AVAS speaker to the measurement microphones. This research delves into understanding the relationship between the transmission of sound over short distances and environmental parameters. Over a one-year period, 122 measurements were conducted using a specially designed dolly setup. The frequency response function, which characterises the sound transmission, was calculated to determine the dependencies and correlations with environmental parameters.