49 research outputs found
Coupled Eulerian Internal Nozzle Flow and Lagrangian Spray Simulations for GDI Systems
No full textAn extensive numerical study of two-phase flow inside the nozzle holes and the issuing jets for a multi-hole direct injection gasoline injector is presented. The injector geometry is representative of the Spray G nozzle, an eight-hole counter-bored injector, from the Engine Combustion Network (ECN). Homogeneous Relaxation Model (HRM) coupled with the mixture multiphase approach in the Eulerian framework has been utilized to capture the phase change phenomena inside the nozzle holes. Our previous studies have demonstrated that this approach is capable of capturing the effect of injection transients and thermodynamic conditions in the combustion chamber, by predicting phenomenon such as flash boiling. However, these simulations were expensive, especially if there is significant interest in predicting the spray behavior as well. This paper presents the development of a one-way Lagrangian approach for Gasoline Direct Injection (GDI) systems, wherein in-nozzle flow simulations can be performed with a small spray chamber domain and the results at the nozzle exit can be used to initialize a Lagrangian spray calculation. This coupled approach will account for the presence of phase-change induced voids at the nozzle exit and hence is expected to be more predictive compared to the standard blob injection model (which does not account for the in-nozzle phenomenon). Results are also compared against the standard Lagrangian simulations using the blob injection model which is initialized using rate of injection measurement (ROI). This work paves the way toward developing and validating a more predictive, but computationally tractable methodology to simulate GDI sprays
Eulerian CFD Modeling of Coupled Nozzle Flow and Spray with Validation Against X-Ray Radiography Data
No full textNumerical simulation of internal and near-nozzle flow of a gasoline direct injection fuel injector
No full textValidation of a Three-Dimensional Internal Nozzle Flow Model Including Automatic Mesh Generation and Cavitation Effects
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Simulations of multiphase flows with multiple length scales using moving mesh interface tracking with adaptive meshing
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Deletion of vitamin D receptor leads to premature emphysema/COPD by increased matrix metalloproteinases and lymphoid aggregates formation
No full textDeficiency of vitamin D is associated with accelerated decline in lung function. Vitamin D is a ligand for nuclear hormone vitamin D receptor (VDR), and upon binding it modulates various cellular functions. The level of VDR is reduced in lungs of patients with chronic obstructive pulmonary disease (COPD) which led us to hypothesize that deficiency of VDR leads to significant alterations in lung phenotype that are characteristics of COPD/emphysema associated with increased inflammatory response. We found that VDR knock-out (VDR(-/-)) mice had increased influx of inflammatory cells, phospho-acetylation of nuclear factor-kappaB (NF-κB) associated with increased proinflammatory mediators, and up-regulation of matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MMP-12 in the lung. This was associated with emphysema and decline in lung function associated with lymphoid aggregates formation compared to WT mice. These findings suggest that deficiency of VDR in mouse lung can lead to an early onset of emphysema/COPD because of chronic inflammation, immune dysregulation, and lung destruction
