Modeling of internal combustion engine thermodynamics, valve dynamics and valve flow

Williams, Paul Ngcebo Tudor (2002-12)

Thesis (MScEng)--University of Stellenbosch, 2002.

Thesis

ENGLISH ABSTRACT: In the design or modification of internal combustion (IC) engine components, the South African Automotive industry has always relied on either design by mother companies or quasi-empirical design methods. These methods have restricted the performance and reliability of local designs. A personal computer based model of four stroke engine operation has been developed as a rapid and cost-effective aid to users who wish to determine the performance of an engine with reasonable accuracy before dynamometer testing is possible. This model consists of a thermodynamic model of combustion and gas exchange linked to a manifold flow model. Accompanying this is a simulation of valve flow and a cam dynamic model, enabling full assessment of the optimum cam profiles and valve angles for various automotive engine configurations. The accuracy of these models has been verified by comparison with a set of engine dynamometer tests. The models have also been used with great success in local and international development projects in conjunction with local automotive manufacturers. In particular, two engine upgrade projects have been successfully completed, in which the program was used to aid the design of inlet manifolds, the selection of camshafts, and the selection of compression ratios.

AFRIKAANSE OPSOMMING: In die ontwerp of modifikasie van binnebrandenjin-komponente het die Suid-Afrikaanse Motorbedryf gewoonlik staatgemaak op óf die ontwerpe van die moedermaatskappy óf is van quasi-empiriese ontwerp metodes gebruik gemaak. Hierdie metodes het die werkverrigting en uithouvermoë van plaaslike ontwerpe beperk. 'n Rekenaar model wat die werking van 'n vierslagenjin moduleer, is ontwikkel as 'n vinnige en koste effektiewe hulpmiddel vir ontwerpers om 'n redelike akkurate voorspelling van enjin werkverrigting te verkry, voordat dynamomotor toetswerk moontlik is. Die model bestaan uit 'n termodinamise model vir ontbranding en die gas uitruilproses, gekoppel aan 'n spruitstuk vloeimodel. Die model word saam met 'n simulasie van klepvloei en 'n nok dinamiese model gebruik, wat toelaat dat 'n goeie raming van die optimum nokprofiele en klephoeke gemaak kan word vir verskeie automobielenjin konfigurasies. Die akuraatheid van hierdie modelle is bevestig deur die vergelyking van simulasie resultate met 'n omvangreike stel enjin dynamomotor toetse. Die modelle is ook met groot sukses in verskeie plaaslike en internasionale ontwikkelingsprojekte, in samewerking met die plaaslike motorbedryf, gebruik. In besonder is twee enjinontwikkelingsprojekte suksesvol voltooi, waarin die simulasie program gebruik is om die ontwerp van die inlaat spruitstuk, die keuse van nokasse en die keuse van drukverhouding te vergemaklik.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52939
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