Valve Flow Coefficients under Engine Operation Conditions: Piston Influence and Flow Pulsation

2019 ◽  
Author(s):  
Sven Fasse ◽  
Michael Grill ◽  
Michael Bargende
Keyword(s):  
Flow Pulsation ◽  
Engine Operation ◽  
Operation Conditions

Estimation of the Occurrence of Micro-Explosion for the Diesel-Biofuel Multi-Components Droplets

2012 ◽  
Author(s):  
Cai Shen ◽  
Chia-fon F. Lee ◽  
Way L. Cheng
Keyword(s):  
Surface Energy ◽  
Minimal Surface ◽  
Weber Number ◽  
Numerical Study ◽  
Engine Operation ◽  
Fuel Droplets ◽  
Fuel Blends ◽  
Operation Conditions ◽  
Simulation Results ◽  
Breakup Model

A numerical study of micro-explosion in multi-component bio-fuel droplets is presented. The onset of micro-explosion is characterized by the normalized onset radius (NOR). Bubble expansion is described by a modified Rayleigh equation. The final breakup is modeled from a surface energy approach by determining the minimal surface energy (MSE). After the breakup, the Sauter mean radius (SMR) for initially small size droplets can be estimated from a look-up table generated from the current breakup model. There exists an optimal droplet size for the onset of micro-explosion. The MSE approach reaches the same conclusion as previous model determining atomization by aerodynamic disturbances. The SMR of secondary droplets can be estimated by the possible void fraction, ε, at breakup and the corresponding surface Weber number, Wes, at the minimal surface energy ratio (MSER). Biodiesel can enhance micro-explosion in the fuel blends of ethanol and diesel (which is represented by a single composition tetradecane). The simulation results show that the secondary atomization of bio-fuel and diesel blends can be achieved by micro-explosion under typical diesel engine operation conditions.

Experimental study on the diesel and biodiesel spray characteristics emerging from equilateral triangular orifice under real diesel engine operation conditions

Fuel ◽  
2018 ◽  
Vol 224 ◽  
pp. 357-365 ◽  
Author(s):  
Shenghao Yu ◽  
Bifeng Yin ◽  
Weixin Deng ◽  
Hekun Jia ◽  
Ze Ye ◽  
...  
Keyword(s):  
Experimental Study ◽  
Diesel Engine ◽  
Spray Characteristics ◽  
Engine Operation ◽  
Operation Conditions

Engine Performance and Emissions Formation for RME and Conventional Diesel Oil: A Comparative Study

2009 ◽  
Author(s):  
Junfeng Yang ◽  
Monica Johansson ◽  
Valeri Golovitchev
Keyword(s):  
Diesel Engine ◽  
Comparative Study ◽  
Soot Formation ◽  
Engine Performance ◽  
Oxidation Mechanism ◽  
Diesel Oil ◽  
Engine Operation ◽  
Operation Conditions ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

A comparative study on engine performance and emissions (NOx, soot) formation has been carried out for the Volvo D12C diesel engine fueled by Rapeseed Methyl Ester, RME and conventional diesel oil. The combustion models, used in this paper, are the modifications of those described in [1–2]. After the compilation of liquid properties of RME specified as methyl oleate, C19H36O2, making up 60% of RME. The oxidation mechanism has been compiled based on methyl butanoate ester, mb, C5H10O2 oxidation model [3] supplemented by the sub-mechanisms for two proposed fuel constituent components, methyl decanoate, md, C11H22O2, n-heptane, C7H16, and soot and NOx formations reduced and “tuned” by using the sensitivity analysis. A special global reaction was introduced to “crack” the main fuel into constituent components, md, mb and propyne, C3H4, to reproduce accurately the proposed RME chemical formula. The sub-mechanisms were collected in the general one consisting of 99 species participating in 411 reactions. The combustion mechanism was validated using shock-tube ignition-delay data at diesel engine conditions and flame propagation speeds at atmospheric conditions. The engine simulations were carried out for Volvo D12C engine fueled both RME and conventional diesel oil. The numerical results illustrate that in the case of RME, nearly 100% combustion efficiency was predicted when the cumulative heat release, was compared with the RME LHV, 37.2 kJ/g.. To minimize NOx emissions, the effects of 20–30% EGR levels depending on the engine loads and different injection strategies were analyses. To confirm the optimal engine operation conditions, a special technique based on the time-transient parametric φ-T maps [4] has been used.

Optimization of TWC Design for Various Engine Operation Conditions

2019 ◽  
Author(s):  
Yuki Toya ◽  
Hiroki Nakayama ◽  
Hiroyuki Hara ◽  
Makoto Nagata
Keyword(s):  
Engine Operation ◽  
Operation Conditions

The Whole-Engine Model for Clearance Evaluation

2009 ◽  
Author(s):  
Alexander N. Arkhipov ◽  
Vladimir V. Karaban ◽  
Igor V. Putchkov ◽  
Guenter Filkorn ◽  
Andreas Kieninger
Keyword(s):  
Steady State ◽  
Transient Analysis ◽  
Operating Experience ◽  
Operating Conditions ◽  
Design Stage ◽  
Fe Model ◽  
Engine Operation ◽  
Engine Model ◽  
Operation Conditions ◽  
3D Effects

The evaluation of the blading clearance at the design stage is important for heavy duty gas turbine efficiency. The minimum clearance value at base load is limited by the pinch point clearance during startup and/or shutdown. Therefore, transient analysis is necessary for different operating conditions. 3D transient analysis of a whole engine is labor-intensive; however 2D axisymmetric analysis does not allow consideration of different 3D effects (e.g. twisting, bending, ovality, rotor alignment). In order to overcome these cost and time limitations, the combination of 2D, axisymmetric, whole-engine model results and the scaled deflections caused by different 3D effects is used for the axial and radial clearance engineering assessment during engine operation. The basic rotor and stator closures are taken from the transient analysis using a 2D finite element (FE) model composed of axisymmetric solid and plane stress elements. To take into account 3D effects of airfoil twisting and bending, the 3D FE displacements of the blade are included in the clearance evaluation process. The relative displacements of airfoil tip and reference point at the blade or vane hub are taken from 3D steady-state FE analyses. Then the steady-state displacements of the airfoils are scaled for transient conditions using the proposed technique. Different 3D rotor / stator effects (cold-build clearances and their tolerances, rotor position with respect to stator after assembly, casing bending, deformations of compressor and turbine vane carrier inducing of casing ovalization, exhaust gas housing movements, movements of the rotor in bearings and CVC and TVC support, etc.) are also included as a contributor to the clearances. The results of the calculations are analyzed and compared with good agreements to the clearances measured in engine testing under real operation conditions. The proposed methodology allows assessing the operating clearances between the stator and rotor during the design phase. Optimization of the running clearance is one key measure to upgrade and improve the engine performance during operating experience.

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