The turbulence measurement during the intake and compression process for high-turbulence generation around spark timing

Abstract

In-cylinder turbulence of an engine was generated by an intake pressure effect and inertia effect during the intake process and it was generated and decreased by the compression effect of a piston during the compression process. The separate measurement of the turbulence generated by these factors during each process was necessary to generate high turbulence around the spark timing. A single-shot rapid intake compression expansion machine (RICEM) was manufactured and evaluated for this purpose. The RICEM could carry out the intake and compression processes separately or in a row. It was proved that the RICEM simulated not only high temperature and high pressure field but also the same flow pattern as a real engine. The turbulence generated by each factor was measured in the swirl field of the RICEM. As the result, it was also found that enhancing the turbulence by the compression effect of a piston with improvement of the flow at the beginning of the compression process was desirable.

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

“…The lack of data may be attributed to challenges associated with making these measurements. In particular, intrusive methods such as hot wire anemometry [205,247] x' is the distance from the center of the reaction chamber, and 'y' is the distance from the piston face. The temperature and velocity field data were acquired from non-reacting experiments at 10 ms (left panels) and 30 ms (right panels) after the end of compression, where the reacting mixtures ignited at 10 and 30 ms, respectively.…”

Investigation of diesel engine performance and emissions by multi-dimensional modeling

“…It is simultaneously described in terms of mixing and progress of reaction as schematically represented in Fig. 1 [27][28]. The differential equations are formulated in a density-weighted ensemble-averaged frame to facilitate the use of mathematical models of the turbulent transport and combustion processes.…”

“…On the subject of auto ignition, two options are also provided, a simple model and a double-delay model for more accurate predictions, especially with engine simulations. For emission simulation, the 3-step Zeldovich model is available for NOx and three options are provided for soot [28]. The Mauss model based on a pre-computed soot source-term library and the PSDF model of moments, where the soot particle size distribution are transported.…”

A Control-Oriented Two-Zone Charge Mixing Model for HCCI Engines With Experimental Validation Using an Optical Engine

“…There exists charge mixing during the compression stroke due to inertial fluidic motion. However, comparably weak turbulent flow exists in a cylinder during the compression stroke [18,19]. Therefore, it can be inferred that charge mixing during the intake stroke is more significant.…”

“…It is mentioned that the turbulent flow, which is generated by intake flow, is the fundamental driving force for mixing and consequentially such turbulence provokes pressure imbalance during the intake stroke [18,19]. From the energy conservation law of a fresh charge in motion, when the fluid jet hits the fictitious divider, its impact pressure is calculated as…”