Virtual design of a novel two-stroke high-speed direct-injection diesel engine

Mattarelli, Enrico

doi:10.1243/14680874jer02509

Cited by 23 publications

(13 citation statements)

References 9 publications

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“…As we will see, the influence of the geometry of the admission duct may be of high importance and should be taken into account by modifications of the compressor map and some elements that simulate the pressure losses. In the first stages of development of new engines is also usual to select a compressor using manufacturer's maps, being critical to this selection the limits imposed by the surge and choke lines [14]. At that point, different admission configurations should be studied so better results can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the inlet air line of an automotive turbocharger

Serrano

Margot

Tiseira

2012

International Journal of Engine Research

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This paper presents different aspects of air inlet behaviour near the inducer of a radial compressor and how the geometry can contribute to its stability and performance. Unfortunately the space reserved for installation of an automotive turbocharger in a vehicle is constantly being reduced, so it is necessary to study the effects that elbows and abrupt changes in flow directions originate on the compressor performance. The work presented in this paper studies the effect that different 90º elbows have on the compressor with respect to its ideal, straight, no-elbow configuration, in order to obtain the best possible elbow configuration.The methodology followed has been to, initially, study different geometries in CFD code in order to obtain the best possible configuration. Then, several 90º elbows were constructed and characterised on a continuous flow test bench in order to validate the CFD results and to obtain optimum results. The elbows were then installed on a radial compressor and tested on a hot, continuous turbocharger test bench, where the compressor was characterised and maps were obtained with each different elbow. The results were compared with respect to the ideal, no-elbow configuration, which was taken as the base performance.After analysing the results obtained, it is possible to observe that in most of the cases the elbows have a negative effect on the compression ratio, which tends to be reduced especially at high rotor velocities and high air mass flow. On the other hand, the effect on the surge limit seems to be positive, as the surge line shifts to lower air mass flows, although the maximum mass flow allowed is reduced. It seems as if the compressor map shifts to the left with a reduction in compression ratio. From theoretical and experimental study it has been concluded that flow uniformity index and pressure loss are the most important factors affecting the performance of the compressor.

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Section: Introductionmentioning

confidence: 99%

Optimization of the inlet air line of an automotive turbocharger

Serrano

Margot

Tiseira

2012

International Journal of Engine Research

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“…This is why two-stroke engines provide higher power, and greater and smoother torque. 6,7 However, they still suffer from high emissions and poor fuel economy compared to more efficient four-stroke engines.…”

Section: The Engine Processmentioning

confidence: 99%

“…Otherwise, some backflow (cf. Figure 2(a)) through the inlet ports would be observed 6 : the burnt gases flow through the intake ports, stopping fresh gases from entering. In addition to possible backflow, the main difficulties with the two-stroke engine and the scavenging process using ports are the mixture of burnt and unburnt gases (cf.…”

Section: Scavenging 21 the Engine Processmentioning

confidence: 99%

A new reduced model of scavenging to optimize cylinder design

et al. 2016

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This paper presents the development of a new scavenging model to optimize cylinder design. The developed model explicitly integrates some of the cylinder's design and environmental variables to describe flows during the scavenging process. Then, based on the reduced model, an optimization phase was carried out in order to determine the optimal values of cylinder variables. From computational fluid dynamics (CFD) models to optimal cylinder design, all method steps used are described in this paper. Adaptable to any type of engine, here it is applied to the particular two-stroke diesel engine with ports only. In order to fully understand fluid flow, the methodology integrates a number of CFD calculations with different cylinder configurations to provide data. The CFD results are used as neural network outputs during the training phase, whereas the cylinder variables plus the crankshaft angle are the inputs. The trained network provides the analytical reduced model for gas composition transiting through ports, which characterize the scavenging process. Thanks to these, genetic algorithms are run to define the most suitable values of cylinder variables in order to improve scavenging. The entire process for establishing the reduced model and the optimal design of the chamber is presented in this paper.

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“…CFD-3D simulations have been performed by using a customized version of the KIVA-3V code, a tool adopted by the authors in a number of previous projects (Cantore and Mattarelli, 2007;De Marco et al, 2007;Mattarelli, 2009;Rinaldini et al, 2011;Mattarelli et al, 2011). Since no prototype has still been built, experimental data are derived from other projects, adopting some empirical hypotheses, discussed in the following.…”

Section: Set-up Of the Design Toolsmentioning

confidence: 99%

CFD optimization of a 2-stroke range extender engine

Mattarelli

Rinaldini

Cantore

2015

Int.J Automot. Technol.

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A very promising concept for small range extenders (peak power less than 40 kW) is represented by the 2-stroke, direct injection spark ignition engine, with scavenging and exhaust ports controlled by the piston, and an external pump. The most important issue to be addressed on this type of engines is the compliance with stringent rules on pollutant emissions, which depends on combustion patterns and the quality of the scavenging process. The latter is generally hindered by the symmetry of ports timings, but this handicap can be canceled by adopting a patented rotary valve, controlling the flow through a set of auxiliary transfer ports, and using a piston pump for delivering air to the power cylinder and enhancing the balance of the crankshaft. The paper reviews the design of a virtual engine, rated at 35 kW at 5600 rpm, and developed according to the above mentioned concepts. Design has been driven by CFD simulation, using, whenever possible, experimentally calibrated numerical models, or experimental information derived from similar projects. Particular care has been devoted to characterize the scavenging process and the flow patterns within the cylinder and through the ports, analyzing the influence of the rotary induction valve. Engine performance parameters have been predicted by using a well-established commercial software (GT-Power, by Gamma Technologies), while CFD-3D analyses have been carried out by means of a customized version of the KIVA-3V code. The whole study is conceived as the basis for the construction of a physical prototype. The power target has been virtually achieved with a very light and compact engine (estimated weight without the close-coupled electric motor: 35 kg). A three-way catalyst allows the engine to comply with the most stringent emission regulations, without relevant penalizations on fuel efficiency. Furthermore, the engine can work with lean mixtures, achieving a minimum specific fuel consumption comparable to a current automotive Diesel engine (223 g/kWh). This excellent result is due to the low friction and pumping losses of the 2-Stroke engine, as well as to the compactness of the combustion chamber and the capability to stratify the charge

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Virtual design of a novel two-stroke high-speed direct-injection diesel engine

Cited by 23 publications

References 9 publications

Optimization of the inlet air line of an automotive turbocharger

Optimization of the inlet air line of an automotive turbocharger

A new reduced model of scavenging to optimize cylinder design

CFD optimization of a 2-stroke range extender engine

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