EVALUATION OF THE PREDICTIVE CAPABILITIES OF A PHENOMENOLOGICAL COMBUSTION MODEL FOR NATURAL GAS SI ENGINE
Abstract
The current study evaluates the predictive capabilities of a new phenomenological combustion model, available as a part of the GT‐Suite software package. It is comprised of two main sub‐models: 0D model of in‐cylinder flow and turbulence, and turbulent SI combustion model.
The 0D in‐cylinder flow model (EngCylFlow) uses a combined K‐k‐ε kinetic energy cascade approach to predict the evolution of the in‐cylinder charge motion and turbulence, where K and k are the mean and turbulent kinetic energies, and ε is the turbulent dissipation rate. The subsequent turbulent combustion model (EngCylCombSITurb) gives the in‐cylinder burn rate; based on the calculation of flame speeds and flame kernel development. This phenomenological approach reduces significantly the overall computational effort compared to the 3D‐CFD, thus allowing the computation of full engine operating map and the vehicle driving cycles.
Model was calibrated using a full map measurement from a turbocharged natural gas SI engine, with swirl intake ports. Sensitivity studies on different calibration methods, and laminar flame speed sub‐models were conducted. Validation process for both the calibration and sensitivity studies was concerning the in‐cylinder pressure traces and burn rates for several engine operation points achieving good overall results.
Predkladaný článok hodnotí prediktívne schopnosti nového fenomenologického modelu horenia, ktorý je k dispozícii ako súčasť softvérového balíka GT‐Suite. Skladá sa z dvoch hlavných sub‐modelov: 0D modelu prúdenia a turbulencie vo valci a zážihového turbulentného modelu horenia.
0D model prúdenia a turbulencie vo valci (EngCylFlow) používa kombinovaný prístup K‐k‐ε kaskády kinetickej energie na predpoveď pohybu zmesi a turbulencie vo valci, kde K a k sú stredné a turbulentné kinetické energie a ε je turbulentná rýchlosť disipácie. Následný model turbulentného horenia (EngCylCombSITurb) určuje rýchlosť horenia vo valci na základe výpočtu rýchlosti čela plameňa a vývoja jadra plameňa. Tento fenomenologický prístup výrazne znižuje celkovú výpočtovú náročnosť v porovnaní s 3D‐CFD, čo umožňuje výpočet úplnej charakteristiky spaľovacieho motora a jazdných cyklov vozidla. Model bol kalibrovaný pomocou meraní úplnej charakteristiky preplňovaného zážihového motora na zemný plyn so swirlovými vstupnými kanálmi. Boli vykonané štúdie citlivosti na rôzne kalibračné metódy a na rôzne sub‐modely laminárnej rýchlosti čela plameňa. Validačný proces pre kalibrácie a štúdie citlivosti sa týkal tlaku vo valci a rýchlostí horenia pre niekoľko pracovných bodov motora, dosahujúc dobré celkové výsledky.
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Copyright (c) 2017 Rastislav Toman, Jan Macek
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