Two-Stroke SI Engine Research Articles

Experimental investigations on SI engine with piston coatings and gasoline blends

Internal combustion engine fuel use is rising, gas prices are fluctuating, we are using less fossil fuels and natural resources, and we need to develop alternative fuels with lower carbon contents. This study compares several gasoline mixtures in a single-cylinder, two-stroke SI engine. The current experimental work provides a thermal barrier for gasoline mixtures containing ethanol, butanol, and propanol by 100-µm piston crown coatings of magnesium partially stabilized zirconium (Mg-PSZ). 20% ethanol and 80% gasoline, 20% butane and 80% gasoline, and 20% propane and 80% gasoline made up the fuel mixture samples. The following engine variables must be assessed in this experiment for coated and uncoated pistons: brake-thermal efficiency (BTH), specific fuel consumption (SFC), and HC and CO emissions. According to the experiment findings, employing E20 resulted in a 4% gain in thermal efficiency, a 1.78% decrease in specific fuel consumption, and a 2.0% and 2.4% decrease in HC and CO exhaust emissions. The results show that heat barrier coatings and gasoline blends (E20) may improve engine performance while lowering exhaust emissions.

Numerical investigation on combustion system optimization for direct injection of aviation kerosene in a two-stroke SI engine for unmanned aerial vehicle

In recent years, the transition from gasoline to heavy fuel has received more and more attention in the application of unmanned aerial vehicles (UAVs). This study aims to convert a two-stroke port fuel injection (PFI) gasoline engine as the prototype engine to a direct injection (DI) aviation kerosene engine by numerical simulations. The direct-injection combustion system was designed, and then the effects of fuel injection timing and ignition strategy on combustion and knock of a two-stroke direct injection spark-ignition (DISI) engine with aviation kerosene as fuel were evaluated. The results show that the direct-injection combustion system can increase the airflow velocity, thereby accelerating fuel diffusion and flame propagation. The knock intensity (KI) and indicated mean effective pressure (IMEP) all decrease with the retardation of the injection timing and spark timing. Injection timing has a greater impact on IMEP than spark timing. For different injection timings, spark timing has a more obvious impact on KI when injection timing is advanced. The coordinated control strategy of advancing injection timing and retarding spark timing can effectively suppress the tendency of knock and broaden its load range, which can make the power recovery rate reach 88.57% compared to the baseline engine.

Numerical Investigation on Combustion System Optimization for Direct Injection of Aviation Kerosene in a Two-Stroke Si Engine for Unmanned Aerial Vehicle

Numerical Investigation on Combustion System Optimization for Direct Injection of Aviation Kerosene in a Two-Stroke Si Engine for Unmanned Aerial Vehicle

Performance and Emission Characterization of Adjustable Cylinder Head Type Variable Compression Ratio in Two-Stroke SI Engine

A lot of technologies have been introduced to retain the petrol engines which exhibit a lot of drawbacks based on emissions and knocking. Variable compression ratio (VCR) technology is applied in the line of SI engines for a long period to give back the standards. This paper is going to analyze and experiment on a commercially available type of VCR technologies. The investigation can provide a great method of varying the compression ratio that is put forth, practically analyzed, and previewed with a change from the previous paper and taken to an account to restrict the compression ratio of +/-1.5. In this analysis, we use the same technology as commercially used two-stroke engines but the clearance volume is changed and introduces a metallic bung on the burning chamber. We have performed the test by varying the compression ratios to more or less than two from the original compression ratio. At lesser weight conditions, a low compression ratio is maintained throughout the experiment to boost up the turbocharger to get a better amount of volumetric efficiency without any trouble. The engine is tested at various compression ratios for the performance study and emissions from the power source at various load conditions. While adopting this method in commercial, we can achieve a potentially higher fuel economy, more power, lower emission compared to other available technologies in ongoing research.

Experimental Studies on Liquid Phase LPG Direct Injection on a Two-Stroke SI Engine

Experimental Studies on Liquid Phase LPG Direct Injection on a Two-Stroke SI Engine

Combustion and Emission Enhancement of a Spark Ignition Two-Stroke Cycle Engine Utilizing Internal and External Exhaust Gas Recirculation Approach at Low-Load Operation

Two-stroke cycle engines have always been prominent due to their distinctive advantage incorporating high power-to-weight ratio, however the drawbacks are poor combustion efficiency, fuel short-circuiting and excessive emission of uHC and CO. These problems are apparent at low-load and speed regions and are the major obstacle to their global acceptance. The deficiencies can be addressed by increasing the in-cylinder average charge temperature employing Exhaust Gas Recirculation (EGR). An experimental study is conducted to investigate the influence of utilizing EGR techniques, including Internal and External EGR, on combustion misfiring occurrence, combustion stability and exhaust emissions using a single cylinder two-stroke SI engine at idling, low and mid-load conditions. From the results, it is observed since the average in-cylinder charge temperature is increased, due to utilizing EGRs, engine’s low and mid-load irregular combustions (misfire) and exhaust emissions are remarkably supressed and almost all of misfire cycles eliminated depending on the percentage of EGRs. In terms of combustion stability, it is agreed in general the application of EGRs improves the cyclic variation of IMEP, Pmax and CA10 compared to conventional operation. However, applying Ex-EGR compared to In-EGR will deteriorate cyclic variability of IMEP and CA10.

Heavy fuel engines

The principle of operation and chosen examples of construction of SI engines designed to be powered with aviation fuel (Heavy Fuel Engines – HFE) have been presented in the article. Contemporary solutions of the HFE combustion system constitute the further development of a patent of an Australian company Orbital working in the field of two-stroke SI engines. Engines of this type, characterized by low weight and low value of specific fuel consumption, are used among others for the propulsion of drones (Unmanned Aerial Vehicles – UAV), where range and endurance are essential parameters. That is also a practical realization of the military logistical concept of using a "single fuel in the battlefield".

Direct injection of gaseous LPG in a two-stroke SI engine for improved performance

Improvements in a two-stroke, spark-ignition (2S–SI) engine can be realized by curtailing short-circuiting losses effectively through direct injection of the fuel. Liquefied petroleum gas (LPG) is an alternative transportation fuel that is used in several countries. However, limited information is available on LPG fuelled direct injected engines. Hence, there is a need to study these systems as applied to 2S–SI engines in order to bring out their potential benefits. A manifold injected 2S–SI engine is modified for direct injection of LPG, in gaseous form, from the cylinder head. This engine is evaluated for performance, emission and combustion. Evaluation at various throttle positions and constant speed showed that this system can significantly improve the thermal efficiency and lower the hydrocarbon (HC) emissions. Up to 93% reduction in HC emissions and improved combustion rates are observed compared to the conventional manifold injection system with LPG. CO emissions are higher and peak NO emissions are lower with this system due to the presence of richer in–cylinder trapped mixtures and charge stratification. This system can operate with similar injection timings at different throttle positions which make electronic control simpler. It can work with low injection pressures in the range of 4–5 bars. All these advantages are attractive for commercial viability of this engine.

Investigation of Scavenging, Combustion and Knock in a Two-Stroke SI Engine Operated with Gasoline and CNG

Investigation of Scavenging, Combustion and Knock in a Two-Stroke SI Engine Operated with Gasoline and CNG

Numerical analysis of combustion and transient heat transfer processes in a two-stroke SI engine

A zero-dimensional model is presented to simulate the transient processes occurring within a two-stroke SI engine. A two zone combustion model, with a spherically expanding flame front originating from the spark location, is applied. The model is numerically solved using the network simulation model which allows coupling the combustion model with a heat transfer model where both radiant and convective heat contributions have been taken into account for the in-cylinder gases. The boundary conditions for this model are the convective heat transferred to the cooling medium. A gas mixture model has been used to obtain the influence of working fluid properties on combustion development.

A Study on In-Cylinder Injection of Low Pressure Natural Gas for Performance Improvement of Small Sized Two-Stroke SI Engines.

Small two stroke SI engines with supplying natural gas in the intake port are advantageous for long maintenance duration and low cost when applied the co-generation and heat pump system for residential use. But in the engine port injection system, the unburned HC emission is higher and thermal efficiency is lower than that of 4 stroke engines. To overcome these disadvantages, the in-cylinder injection with special low pressure injection nozzle system was attempted. The results showed that the improvements of unburned HC emission and thermal efficiency are possible due to the remarkable reduction of scavengjng loss and the lean combustion.