Change search
ReferencesLink to record
Permanent link

Direct link
1D engine simulation of a turbocharged SI engine with CFD computation on components
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2008 (English)Licentiate thesis, monograph (Other scientific)
Abstract [en]

Techniques that can increase the SI- engine efficiency while keeping the emissions very low is to reduce the engine displacement volume combined with a charging system. Advanced systems are needed for an effective boosting of the engine and today 1D engine simulation tools are often used for their optimization.

This thesis concerns 1D engine simulation of a turbocharged SI engine and the introduction of CFD computations on components as a way to assess inaccuracies in the 1D model.

1D engine simulations have been performed on a turbocharged SI engine and the results have been validated by on-engine measurements in test cell. The operating points considered have been in the engine’s low speed and load region, with the turbocharger’s waste-gate closed.

The instantaneous on-engine turbine efficiency was calculated for two different turbochargers based on high frequency measurements in test cell. Unfortunately the instantaneous mass flow rates and temperatures directly upstream and downstream of the turbine could not be measured and simulated values from the calibrated engine model were used. The on-engine turbine efficiency was compared with the efficiency computed by the 1D code using steady flow data to describe the turbine performance.

The results show that the on-engine turbine efficiency shows a hysteretic effect over the exhaust pulse so that the discrepancy between measured and quasi-steady values increases for decreasing mass flow rate after a pulse peak.

Flow modeling in pipe geometries that can be representative to those of an exhaust manifold, single bent pipes and double bent pipes and also the outer runners of an exhaust manifold, have been computed in both 1D and 3D under steady and pulsating flow conditions. The results have been compared in terms of pressure losses.

The results show that calculated pressure gradient for a straight pipe under steady flow is similar using either 1D or 3D computations. The calculated pressure drop over a bend is clearly higher1D engine simulations of turbocharged engines are difficult to using 1D computations compared to 3D computations, both for steady and pulsating flow. Also, the slow decay of the secondary flow structure that develops over a bend, gives a higher pressure gradient in the 3D calculations compared to the 1D calculation in the straight pipe parts downstream of a bend.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 2, 106 p.
Trita-MMK, ISSN 1400-1179 ; 2008:09
Keyword [en]
1D modeling, CFD modeling, turbine efficiency, pipe flow, turbocharged engine
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-9162ISBN: 978-91-7415-099-5OAI: diva2:25350
2008-09-05, M3, Brinellvägen 64, Stockholm, 10:00
QC 20101119Available from: 2008-06-13 Created: 2008-09-26 Last updated: 2010-11-19Bibliographically approved

Open Access in DiVA

fulltext(5411 kB)2010 downloads
File information
File name FULLTEXT01.pdfFile size 5411 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Renberg, Ulrica
By organisation
Machine Design (Dept.)
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 2010 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 377 hits
ReferencesLink to record
Permanent link

Direct link