Powertrain Simulation Tools and Application to the Development of a SI Engine Concept Car

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

Alix²,

Wasselin³

et al. 2013

Reducing greenhouse gas emissions to limit global warming is becoming one of the key issues of the 21st century. Today, the transport sector is considered as one of the main contributor to this phenomenon and represented 24% of the world's CO 2 emissions in 2011. In the last decade the different transport sectors have thus decided to take measures and incentives to limit or reduce these emissions. For example, in the aeronautic field, the Advisory Council for Aeronautics Research (ACARE) wishes a reduction of about 50% for the CO 2 emissions of air transport before 2020 and about 65% in 2050 1 in Europe. These ambitious targets need to implement major improvements in existing propulsion system or to use ground-braking technologies. In this context, solutions based on Diesel Internal Combustion Engines (ICE) could be a relevant alternative way to succeed in drastic reduction of fuel consumption for low and medium power applications (<1000kW), including light-weight aircrafts, UAV, APU or medium to light-weight rotorcrafts. Indeed, in this range of applications, the specific fuel consumption of a Diesel ICE is, at least, 30 to 40% less than an equivalent turboshaft able to deliver the same power. Combined with complementary technological breakthroughs such as electrification 2,3 , potential benefits could then reach targets envisaged by ACARE. Nevertheless, the specific development of ICE's adapted to aeronautic purposes is a very complex process during which simulations tools have a key role to play for highlighting the most promising paths to explore. The objective of this paper is therefore to study the potential of high power density Diesel engines for the particular application of a rotorcraft. This simulation study takes into account realistic constraints (power, compactness, power to weight ratio, fuel economy...) and is notably focused on dedicated engine architectures, including two and four strokes configurations.. An evaluation of fuel consumption in realistic flight conditions is then performed coupling engine models with a helicopter simulator. The use of Diesel ICE leads to fuel consumption gains of the order of 40% but also increases the possible payload for long-range missions, compared to present turboshafts. The paper finally allows to draw perspectives of developments for future green rotorcrafts but also more generally for light and medium weight aeronautic applications. Nomenclature4T = Four-stroke engine 2T = Two stroke engine 2 CA50 = Crank Angle at which 50% of the fuel has burnt ICE = Internal Combustion Engine ISFC = Indicated Specific Fuel Consumption OGE = Out of ground effect SAR = Search and Rescue TM = Turbomachine (turboshaft) VBE = Best consumption operating speed VBR = Best range (autonomy) operating speed Vmax = Maximum speed

Section: Simulation Platformmentioning

confidence: 99%

Potential of high power density Diesel engines for green rotorcrafts propulsion

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

Alix²,

Wasselin³

et al. 2013

“…The virtual engine system simulator has been built using the IFP-Engine library developed at IFPEN and the available in the LMS.Imagine.Lab AMESim environment 9 . This tool gives access to a detailed description of engine operation using a characteristic time-scale of the order of the crankshaft angle.…”

Section: Numerical Simulationsmentioning

confidence: 99%

A comprehensive workflow combining numerical and experimental tools to study the combustion of aviation fuels in Diesel aircraft engines

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

2013

Reducing greenhouse gas emissions to limit global warming is becoming one of the main concern of the aeronautic industry. For example, in Europe, the Advisory Council for Aeronautics Research (ACARE) wishes a reduction of about 50% for the CO 2 emissions of air transport before 2020 and about 65% in 2050 1 . For low and medium power applications (<1000 kW) such reductions could be achieved using dedicated Diesel Internal Combustion Engines (ICE) thanks to the huge progresses performed in the automotive industry and motorsport field during the last decade. However, the development of Diesel engines in the aeronautic context is not straightfoward because the operating conditions and fuel (Jet) characteristics differ from those of ground transportation. The objective of this study was thus to build a comprehensive workflow allowing a detailed analysis of the combustion of any aviation fuels (conventional or alternative) in Diesel aircraft engines. Such a workflow combines experimental and numerical tools including ground engine tests, spray characterization in high pressure vessels, tools for physical and chemical properties generation, virtual 1D engine simulators and 3D CFD computations of the combustion chamber. One key idea of this approach is that in-flight operation are finally studied using 3D CFD, all the other tools being used to generate input data, initial and boundary conditions to these simulations. In the present paper, the proposed workflow is used to compare Diesel and a given Jet-A1 fuel, with a cetane index of 47, in order to highlight the interest of this approach.

“…Few years ago, its use was restricted to the evaluation of air-path configurations, but it has been recently extended to the development of engine control strategies thanks to the new real-time capabilities of 0-D engine simulators [1][2][3], which can now partially replace engine benches. In a near future, system simulation could also be used more intensively in the design process of combustion systems to recommend optimal engine settings (ignition and injection timings, fuel, air-ratios...), geometrical dimensions (compression ratio, bore and stroke...), or to evaluate the effect of new fuels on the engine behavior, as illustrated in recent works [4,5].…”

Section: Introductionmentioning

confidence: 99%

A 0-D flame wrinkling equation to describe the turbulent flame surface evolution in SI engines

Comptes Rendus Mécanique

Veynante

2015

The current development of reciprocating engines relies increasingly on system simulation for both design activities and conception of algorithms for engine control. These numerical simulation tools require high computational efficiencies, as calculations have to be performed in times close to real-time. Then, they are today mainly based on simple empirical laws to describe the combustion processes in the cylinders. However, with the rapid evolution of emission regulations and fuel formulation, more and more physics is expected in combustion models. A solution consists in reducing 3-D combustion models to build 0-dimensional models that are both CPU-efficient and based on physical quantities. This approach has been used in a previous work to reduce the 3-D ECFM (Extended Coherent Flame Model), leading to the so-called CFM1D. A key feature of the latter is to be based on a 0-D equation for the flame wrinkling derived from the 3-D equation for the flame surface density. The objective of this paper is to present in details the theoretical derivation of the wrinkling equation and the underlying modeling assumptions as well. Academic validations are performed against experimental data for several turbulence intensities and fuels. Finally, the proposed model is applied to engine simulations for a wide range of operating conditions. Comparisons are successfully conducted between incylinder measurements and the model predictions, highlighting the interest of reducing 3-D CFD models for calculations performed in the context of system simulation.