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Title: Investigation of nozzle flow and cavitation characteristics in a diesel injector.

Abstract

Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a computational investigation of the internal nozzle flow and cavitation characteristics in a diesel injector. A mixture based model in FLUENT V6.2 software is employed for simulations. In addition, a new criterion for cavitation inception based on the total stress is implemented, and its effectiveness in predicting cavitation is evaluated. Results indicate that under realistic diesel engine conditions, cavitation patterns inside the orifice are influenced by the new cavitation criterion. Simulations are validated using the available two-phase nozzle flow data and the rate of injection measurements at various injection pressures (800-1600 bar) from the present study. The computational model is then used to characterize the effects of important injector parameters on the internal nozzle flow and cavitation behavior, as well as on flow properties at the nozzle exit. The parameters include injection pressure, needle lift position, and fuel type. The propensity of cavitation for different on-fleetmore » diesel fuels is compared with that for n-dodecane, a diesel fuel surrogate. Results indicate that the cavitation characteristics of n-dodecane are significantly different from those of the other three fuels investigated. The effect of needle movement on cavitation is investigated by performing simulations at different needle lift positions. Cavitation patterns are seen to shift dramatically as the needle lift position is changed during an injection event. The region of significant cavitation shifts from top of the orifice to bottom of the orifice as the needle position is changed from fully open (0.275 mm) to nearly closed (0.1 mm), and this behavior can be attributed to the effect of needle position on flow patterns upstream of the orifice. The results demonstrate the capability of the cavitation model to predict cavitating nozzle flows in realistic diesel injectors and provide boundary conditions, in terms of vapor fraction, velocity, and turbulence parameters at the nozzle exit, which can be coupled with the primary breakup simulation.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
EE
OSTI Identifier:
977037
Report Number(s):
ANL/ES/JA-62050
Journal ID: ISSN 0742-4795; JETPEZ; TRN: US201009%%178
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
J. Eng. Gas Turbines Power
Additional Journal Information:
Journal Volume: 132; Journal Issue: Apr. 2010; Journal ID: ISSN 0742-4795
Country of Publication:
United States
Language:
ENGLISH
Subject:
33 ADVANCED PROPULSION SYSTEMS; BOUNDARY CONDITIONS; CAVITATION; DIESEL ENGINES; DIESEL FUELS; ELEVATORS; MIXTURES; NOZZLES; ORIFICES; PRESSURE GRADIENTS; SIMULATION; TURBULENCE; TWO-PHASE FLOW; VELOCITY

Citation Formats

Som, S, Ramirez, A, Aggarwal, S, El-Hannouny, E, Longman, D, Energy Systems, and Univ. of Illinois. Investigation of nozzle flow and cavitation characteristics in a diesel injector.. United States: N. p., 2010. Web. doi:10.1115/1.3203146.
Som, S, Ramirez, A, Aggarwal, S, El-Hannouny, E, Longman, D, Energy Systems, & Univ. of Illinois. Investigation of nozzle flow and cavitation characteristics in a diesel injector.. United States. https://doi.org/10.1115/1.3203146
Som, S, Ramirez, A, Aggarwal, S, El-Hannouny, E, Longman, D, Energy Systems, and Univ. of Illinois. 2010. "Investigation of nozzle flow and cavitation characteristics in a diesel injector.". United States. https://doi.org/10.1115/1.3203146.
@article{osti_977037,
title = {Investigation of nozzle flow and cavitation characteristics in a diesel injector.},
author = {Som, S and Ramirez, A and Aggarwal, S and El-Hannouny, E and Longman, D and Energy Systems and Univ. of Illinois},
abstractNote = {Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a computational investigation of the internal nozzle flow and cavitation characteristics in a diesel injector. A mixture based model in FLUENT V6.2 software is employed for simulations. In addition, a new criterion for cavitation inception based on the total stress is implemented, and its effectiveness in predicting cavitation is evaluated. Results indicate that under realistic diesel engine conditions, cavitation patterns inside the orifice are influenced by the new cavitation criterion. Simulations are validated using the available two-phase nozzle flow data and the rate of injection measurements at various injection pressures (800-1600 bar) from the present study. The computational model is then used to characterize the effects of important injector parameters on the internal nozzle flow and cavitation behavior, as well as on flow properties at the nozzle exit. The parameters include injection pressure, needle lift position, and fuel type. The propensity of cavitation for different on-fleet diesel fuels is compared with that for n-dodecane, a diesel fuel surrogate. Results indicate that the cavitation characteristics of n-dodecane are significantly different from those of the other three fuels investigated. The effect of needle movement on cavitation is investigated by performing simulations at different needle lift positions. Cavitation patterns are seen to shift dramatically as the needle lift position is changed during an injection event. The region of significant cavitation shifts from top of the orifice to bottom of the orifice as the needle position is changed from fully open (0.275 mm) to nearly closed (0.1 mm), and this behavior can be attributed to the effect of needle position on flow patterns upstream of the orifice. The results demonstrate the capability of the cavitation model to predict cavitating nozzle flows in realistic diesel injectors and provide boundary conditions, in terms of vapor fraction, velocity, and turbulence parameters at the nozzle exit, which can be coupled with the primary breakup simulation.},
doi = {10.1115/1.3203146},
url = {https://www.osti.gov/biblio/977037}, journal = {J. Eng. Gas Turbines Power},
issn = {0742-4795},
number = Apr. 2010,
volume = 132,
place = {United States},
year = {Thu Apr 01 00:00:00 EDT 2010},
month = {Thu Apr 01 00:00:00 EDT 2010}
}