Development of a Combustion Process for a High Performance 2-Stroke Engine with High Pressure Direct Injection

Author(s):  
Stephan Schmidt ◽  
Franz Winkler ◽  
Oliver Schoegl ◽  
Michael Pontoppidan
Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2846 ◽  
Author(s):  
Marco Ciampolini ◽  
Simone Bigalli ◽  
Francesco Balduzzi ◽  
Alessandro Bianchini ◽  
Luca Romani ◽  
...  

The research on two-stroke engines has been focused lately on the development of direct injection systems for reducing the emissions of hydrocarbons by minimizing the fuel short-circuiting. Low temperature combustion (LTC) may be the next step to further improve emissions and fuel consumption; however, LTC requires unconventional ignition systems. Jet ignition, i.e., the use of prechambers to accelerate the combustion process, turned out to be an effective way to perform LTC. The present work aims at proving the feasibility of adopting passive prechambers in a high-pressure, direct injection, two-stroke engine through non-reactive computational fluid dynamics analyses. The goal of the analysis is the evaluation of the prechamber performance in terms of both scavenging efficiency of burnt gases and fuel/air mixture formation inside the prechamber volume itself, in order to guarantee the mixture ignitability. Two prechamber geometries, featuring different aspect ratios and orifice numbers, were investigated. The analyses were replicated for two different locations of the injection and for three operating conditions of the engine in terms of revolution speed and load. Upon examination of the results, the effectiveness of both prechambers was found to be strongly dependent on the injection setup.


Author(s):  
Andrew Findlay ◽  
Nicholas Harker ◽  
Karen R. Den Braven

A turbocharged gasoline direct injection (GDI) two-stroke engine for use in snowmobile applications has been developed. Applying GDI to a two-stroke engine significantly reduces emissions of unburned hydrocarbons and improves fuel economy by reducing or eliminating the short-circuiting of fuel that occurs in conventional carbureted two-stroke engines. Performance is a high priority for recreational enthusiasts. Direct-injection also allows for further improvement in power and efficiency through the use of exhaust turbocharging. With the scavenging and fuel flows separated, turbocharging can efficiently increase the mass of air delivered to the engine. This increases specific power output and decreases specific fuel consumption. Results show that the brake specific fuel consumption (BSFC) of the turbocharged engine was improved over the entire engine operating range compared to the naturally aspirated engine. It was seen that a mild boost pressure of 5 psi could increase power by 40 brake-horsepower (bhp) at the peak engine speed and over 60 bhp at lower engine speeds. The results show that turbocharged direct injection is a viable option for high performance two-stroke engines.


Author(s):  
Gerald J. Micklow ◽  
Krishna Ankem ◽  
Tarek Abdel-Salam

Understanding the physics and chemistry involved in spray combustion, with its transient effects and the inhomogeneity of the spray is quite challenging. For efficient operation of both internal combustion and gas turbine engines, great insight into the physics of the problem can be obtained when a computational analysis is used in conjunction with either an experimental program or through published experimental data. The main area to be investigated to obtain good combustion begins with the fuel injection process and an accurate description of the mean diameter of the fuel particle, injection pressure, drag coefficient, rate shaping etc must be defined correctly. This work presents a methodology to perform the task set out in the previous paragraph and uses experimental data obtained from available literature to construct a semi-empirical numerical model for high pressure fuel injectors. A modified version of a multidimensional computer code called KIVA3V was used for the computations, with improved sub-models for mean droplet diameter, injection pressure, injection velocity, and drop distortion and drag. The results achieved show good agreement with the published in-cylinder experimental data for a Volkswagen 1.9 L turbo-charged direct injection internal combustion engine under actual operating conditions. It is crucial to model the spray distribution accurately, as the combustion process and the resulting temperature distribution and pollutant emission formation is intimately tied to the in-cylinder fuel distribution. The present scheme has achieved excellent agreement with published experimental data and will make an important contribution to the numerical simulation of the combustion process and pollutant emission formation in compression ignition direct injection engines and gas turbine engines.


Alloy Digest ◽  
2015 ◽  
Vol 64 (1) ◽  

Abstract Sandvik Pressurfect is an austenitic chromium-nickel stainless steel with low carbon content used for high-pressure gasoline direct injection (GDI) fuel system. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: SS-1195. Producer or source: Sandvik Steel Company.


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