Three-Dimensional Multi-phase Physics-Based Modeling Methodology to Study Engine Cylinder-kit Assembly Tribology and Design Considerations- Part I

Abstract

<div class="section abstract"><div class="htmlview paragraph">Understanding cylinder-kit tribology is pivotal to durability, emission management, reduced oil consumption, and efficiency of the internal combustion engine. This work addresses the understanding of the fundamental aspects of oil transport and combustion gas flow in the cylinder kit, using simulation tools and high-performance computing. A dynamic three-dimensional multi-phase, multi-component modeling methodology is demonstrated to study cylinder-kit assembly tribology during the four-stroke cycle of a piston engine. The percentage of oil and gas transported through different regions of the piston ring pack is predicted, and the mechanisms behind this transport are analyzed. The velocity field shows substantial circumferential flow in the piston ring pack, leading to blowback into the combustion chamber during the expansion stroke. Oil initialization and management of a continuous supply of oil throughout the cycle are observed to govern how much oil would be lost to the crankcase and combustion chamber. The calculated blow-by results agree with the results of a quasi-one-dimensional cylinder-kit analysis system of programs known as CASE (Cylinder-kit Analysis System for Engines). Implementing this three-dimensional methodology leads to a better understanding of cylinder-kit fluid flow physics. The findings presented in this work pave the way to further the ongoing development effort of optimum cylinder kit designs with controlled gas leakage, low oil consumption, and low cylinder kit friction.</div></div>

Insights into modeling approaches for boundary- and mixed-lubricated conditions

“…Moreover, significant research effort has been dedicated towards the development and verification of multi-phase models. The interested reader is referred to the state-of-the-art literature (Shahmohammadi and Jafari, 2014; Abidi et al , 2021; Shahmohamadi et al , 2017; Chowdhury et al , 2020; Khanafer and Vafai, 2021).…”

Hybrid digital twin for conditional lubricant oil transport simulation and oil consumption prediction in internal combustion engines

“…stagnation loss (14) where The loss function defined by equation ( 14) consists of two terms. The first term is the squared loss which compares the overall quality of the machine learning prediction across the entire flow domain against the actual data.…”

“…where the term definitions follow those in equation (14). Notice that even though the change in velocity magnitude and direction is the most prominent within a small region around the outlet, the loss in this region is not included as an additional term since, unlike the symmetric pattern observed in the circulation flow field, the exact flow pattern around the outlet cannot be determined a priori because of the possibility for an asymmetric flow field, and thus a pre-defined region cannot be drawn.…”

“…There also exists a 3D multi-phase model for oil transport. 14,15 Design parameters of the piston ring pack and engine operating conditions are used to calculate various quantities of interest, including the pressure environment, piston ring dynamics and ring conformability, which are then imported to a commercial CFD package to simulate oil transport in the piston ring pack. A separate 2D multi-phase simulation on oil transport from piston ring grooves was also performed.…”