The in-cylinder ow eld and the turbulence scale at the ignition timing play an important role in enhancing the propagation speed of the initial ame and the engine combustion. The aim of this work is to investigate the e ect of tumble and swirl ows on the turbulence scale near the top dead centre in a four-valve spark ignition (SI ) engine by an experimental method. In this study, various ow elds such as tumble and swirl ows were generated by intake ow control valves. For investigation of the ow elds, the single-frame particle tracking velocimeter (PTV ) and the twocolour particle image velocimeter (PIV ) techniques were developed to clarify the in-cylinder ow pattern during the intake stroke and the turbulence intensity near the spark plug during the compression stroke respectively. In addition, the ame propagation was visualized by an ICCD camera, and its images were analysed to compare the ow elds. From these experimental results, the e ects of tumble and swirl ows on the turbulence scale and the ame propagation speed were clari ed.
An isoparametric quadratic formulation of the boundary integral equation (BIE) method for two-dimensional elastoplastic analysis is presented. The initial strain approach is adopted but, unlike in finite element analysis, it is capable of accurately treating perfectly-plastic and weakly strain-hardening materials. Two methods of evaluating internal stress and strain rates, namely, via the elementwise numerical differentiation of the displacement rates, and the pointwise use of integral identities, are included in the solution algorithm, and their relative efficiency is discussed. The use of correction factors is suggested in some cases to ensure that the von Mises flow rules are implemented in a consistent manner. Results to test problems are given and compared with exact or existing approximate solutions.
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