The effect of inlet swirl on knock limits in spark ignition engines

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dc.contributor.advisorPriede, Ten_ZA
dc.contributor.authorAllison, Colin Biddenen_ZA
dc.date.accessioned2016-04-05T11:42:57Z
dc.date.available2016-04-05T11:42:57Z
dc.date.issued1992en_ZA
dc.description.abstractAn investigation was undertaken to determine the effect of swirl ratio on knock limits in spark ignition engines. Initially it was attempted to find a correlation between swirl ratio and Knock Limited Spark Advance (KLSA) for a selection of commercially available engines. A comparison of measured swirl ratios and KLSA indicated that no such correlation could be found. This was put down to the fact that other factors such as combustion chamber shape and spark plug location play a more dominant role in affecting knock limits than swirl level. Following from this, a single engine with a relatively poor swirl ratio was selected and the swirl level was altered. A novel method of increasing and decreasing the swirl level, with the same pressure drop in each case was developed, and this development is described. This method made it possible to perform dynamometer tests, measuring the KLSA timing for the cases of low and high swirl, while keeping all other parameters such as pressure, temperature, spark plug location and combustion chamber shape constant. All these factors are known to have an effect on the occurrence of knock. In this manner it was possible to determine whether swirl alone has any effect on knock limits. It was found that the high swirl case exhibited higher values of knock limited spark advance above the low swirl case although there was no significant change in torque. A comparison of rubber castings of the inlet ports of numerous engines was made, and is presented in a photographic form. This was done in order to assess how inlet port geometry affects swirl ratios. It was found that a helically shaped inlet port produced the greatest swirl ratio, non directed ports have average values and multiple inlet valve ports have very low swirl ratios. Furthermore, a comparison of swirl ratios of an inlet port with and without deposits, demonstrates that deposits have a significant effect on swirl ratios and volumetric efficiency. However, although the volumetric efficiency was reduced, the deposits enhanced the swirl ratios for this particular case. This is contrary to the general belief that deposits reduce swirl.en_ZA
dc.identifier.apacitationAllison, C. B. (1992). <i>The effect of inlet swirl on knock limits in spark ignition engines</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering. Retrieved from http://hdl.handle.net/11427/18604en_ZA
dc.identifier.chicagocitationAllison, Colin Bidden. <i>"The effect of inlet swirl on knock limits in spark ignition engines."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 1992. http://hdl.handle.net/11427/18604en_ZA
dc.identifier.citationAllison, C. 1992. The effect of inlet swirl on knock limits in spark ignition engines. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Allison, Colin Bidden AB - An investigation was undertaken to determine the effect of swirl ratio on knock limits in spark ignition engines. Initially it was attempted to find a correlation between swirl ratio and Knock Limited Spark Advance (KLSA) for a selection of commercially available engines. A comparison of measured swirl ratios and KLSA indicated that no such correlation could be found. This was put down to the fact that other factors such as combustion chamber shape and spark plug location play a more dominant role in affecting knock limits than swirl level. Following from this, a single engine with a relatively poor swirl ratio was selected and the swirl level was altered. A novel method of increasing and decreasing the swirl level, with the same pressure drop in each case was developed, and this development is described. This method made it possible to perform dynamometer tests, measuring the KLSA timing for the cases of low and high swirl, while keeping all other parameters such as pressure, temperature, spark plug location and combustion chamber shape constant. All these factors are known to have an effect on the occurrence of knock. In this manner it was possible to determine whether swirl alone has any effect on knock limits. It was found that the high swirl case exhibited higher values of knock limited spark advance above the low swirl case although there was no significant change in torque. A comparison of rubber castings of the inlet ports of numerous engines was made, and is presented in a photographic form. This was done in order to assess how inlet port geometry affects swirl ratios. It was found that a helically shaped inlet port produced the greatest swirl ratio, non directed ports have average values and multiple inlet valve ports have very low swirl ratios. Furthermore, a comparison of swirl ratios of an inlet port with and without deposits, demonstrates that deposits have a significant effect on swirl ratios and volumetric efficiency. However, although the volumetric efficiency was reduced, the deposits enhanced the swirl ratios for this particular case. This is contrary to the general belief that deposits reduce swirl. DA - 1992 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1992 T1 - The effect of inlet swirl on knock limits in spark ignition engines TI - The effect of inlet swirl on knock limits in spark ignition engines UR - http://hdl.handle.net/11427/18604 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/18604
dc.identifier.vancouvercitationAllison CB. The effect of inlet swirl on knock limits in spark ignition engines. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 1992 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18604en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Mechanical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMechanical Engineeringen_ZA
dc.titleThe effect of inlet swirl on knock limits in spark ignition enginesen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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