Improvement of a High-Performance CNG-Engine Based on an innovative Virtual Development Process FKFS

Format:

Conference/Event

Author/Creator:

Chiodi, Chiodi, author.

Contributor:

Bargende, Michael

Ferrari, Alessandro

Mack, Oliver

Wichelhaus, Donatus

Conference Name:

10th International Conference on Engines & Vehicles (2011-09-11 : Naples, Italy)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2011

Summary:

Methane as an alternative fuel in motorsports? Actually thissolution is well known for the reduction of CO₂ emissions butapparently it does not really awake race feelings. At the 2009edition of the 24-hour endurance race on the Nürburgring theVolkswagen Motorsport GmbH, in addition to vehicles powered bygasoline engines, introduced two vehicles powered by innovativeturbo-charged CNG engines for the first time. The aim was to prove,that also an "environment-friendly" concept is able toprovide the required efficiency, dynamic and reliability for asuccessful participation in motorsports. After the success in the2009 edition the engagement has been continued also in 2010, thistime exclusively with CNG vehicles.Focusing on the CO₂ emission, reclusively the higher hydrogencontent of methane which represents the main component of NG leadsto a CO₂ reduction during the combustion of about 20% compared togasoline. Thanks to the laminar burning speed of methane which isapproximately maximal for a stoichiometric mixture, CNG engines donot require a mixture enrichment at WOT operating conditions, sothat the fuel consumption decreases. In addition the very highknock-resistance of natural gas allows a further efficiencyincreasing by using a higher compression ratio. Conclusively theCO₂ reduction of the CNG version ranges from ca. 30% using naturalgas up to 80% for bio-gas. On the other hand gas injection in theintake manifold causes a loss of charge due to both the low massdensity of natural gas and the absence of heat of vaporization. Thelatter also produces a temperature level of the exhaust gas at theturbine which is more critical. Another drawback of CNG engines isthe homogenization of the air-fuel mixture. This process is morecritical because even high gas velocities at the injector nozzlecause a very low fuel penetration. Therefore, mixturehomogenization or stratification depends much more on charge motionas usual for liquid fuels. For this reason the design of the intakesystem and the combustion chamber is a crucial step for theoptimization of a CNG engine.In this paper the engine development process has been performedmainly in a virtual context. The implementation of an innovative3D-CFD tool (QuickSim) that has permitted full-engine simulationsof this turbocharged CNG race-engine has allowed, within short time(few months), to remarkably increase the engine performance. Thevirtual engine development process has started with the 3D-CFDanalysis of the fluid motion of the basic engine. Based on thisanalysis, many engine-design modifications have then been virtuallytested, so that at the end only a few promising solutions have been"concretely" realized and tested at the test bench. Sincethe results at the test bench have finally confirmed theexpectations from the simulation results, following this procedureit has been definitively possible to speed up the enginedevelopment process even by limiting the budget

Notes:

Vendor supplied data

Publisher Number:

2011-24-0140

Access Restriction:

Restricted for use by site license