| The flow fields inside the engine cylinder are extremely complex and exhibit large cycle-to-cycle variations. It is the most important factor that controls the combustion process. It governs the fuel-air mixing and burning rates inside the engine cylinder. Therefore, it is desirable to improve the measurement techniques for velocity measurements and scalar properties pertaining to the in-cylinder flows. In this dissertation, molecular tagging velocimetry (MTV) is used to obtain the multiple point measurement of the instantaneous velocity field inside the engine cylinder. MTV is a molecular counterpart of particle-based techniques, and it eliminates the use of seed particles.;In the first part of this work, an experimental study is performed to investigate the effects of charge motion control on in-cylinder flow (using MTV). It is found that the charge motion control has a profound effect on cycle-to-cycle variations during the intake and early compression; however, its influence reduces during the late compression. In-cylinder engine flow measurements are extended to obtain an instantaneous three-component velocity field using stereoscopic molecular tagging velocimetry (SMTV). The image-processing technique, implemented to obtain the three-components of velocity, involves two major steps: (i) calibration process and (ii) data acquisition and reduction. Preliminary results show that the cycle-to-cycle variations are more prominent in the velocity component perpendicular to the tumble plane, as opposed to the in-plane components. Such new insights will help better understand the details of these flows and further improve CFD models for IC engines.;Experimental measurements provide useful information of the flow fields inside the engine cylinder. However, it is multi-dimensional numerical simulations that offer the potential of significant time and cost savings to design the engine with improved performance. To date, numerical simulations of in-cylinder flows are performed with assumed boundary conditions. Due to this, flow measurements are performed inside the intake manifold of an engine assembly that can provide real-time boundary conditions for more accurate multi-dimensional numerical simulations. The geometry of the intake manifold is simplified for this purpose. A hot-wire anemometer and piezoresistive type absolute pressure transducers are used to measure the velocity and pressure, respectively. In-cylinder flow measurements are also performed (using SMTV) to validate the modeling efforts.;In the second part of this work, in-cylinder combustion diagnosis is performed inside an ethanol-gasoline, dual fueled, single-cylinder spark ignition engine. A dual fuel injection system with both direct-injection (DI) and port-fuel-injection (PFI) is used. The cycle-to-cycle variability is presented using the coefficient of variation of indicated mean effective pressure. Mass fraction burned and burn duration are determined from the analysis of measured in-cylinder pressure data. |
