Two Phase Flow Downstream of a Multipoint Lean Direct Injection Low NOx Nozzle

2003 ◽  
Author(s):  
Mohamed Boutazakhti ◽  
Ibrahim Yimer ◽  
Pierre E. Sullivan ◽  
Murray J. Thomson
Keyword(s):  
Direct Injection ◽  
Injection Pressure ◽  
Exit Plane ◽  
Atmospheric Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Lean Direct Injection ◽  
Liquid Injection ◽  
Single Jet ◽  
Spray Field

This work examines the flow downstream of a Parker Hannifin low NOx LDI nozzle. The nozzle is a square matrix of 3 × 3 airblast simplex fuel ports. The air pressure drop was set to 5%, for a Reynolds number of 40,000. Liquid injection pressure was 2.28kPa. The nozzle is tested at atmospheric conditions without combustion. The objective of this work is twofold: first characterize the spray and the turbulent flow fields; and second examine the effect of the interaction between jets on turbulence and spray profiles. Jet-jet lateral impingement starts within ∼ 1–2 nozzle diameters downstream. The comparison of a single jet and the 3 × 3 matrix spray profiles shows some degree of coalescence due to the interaction between jets. Despite this, the Sauter mean diameter of the resulting spray field is in the 25–35 μm range. In the first few air swirl cup diameters downstream of the nozzle exit plane (down to z/D = 3), the droplets are still accelerating to the air velocity and turbulence is anisotropic. No–slip and turbulence isotropy assumption are accurate only well downstream of the exit plane (z/D = 7.5).

A Predictive Ignition Delay Correlation Under Steady-State and Transient Operation of a Direct Injection Diesel Engine

2003 ◽  
Vol 125 (2) ◽  
pp. 450-457 ◽  
Author(s):  
D. N. Assanis ◽  
Z. S. Filipi ◽  
S. B. Fiveland ◽  
M. Syrimis
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Ignition Delay ◽  
Direct Injection ◽  
Thermodynamic Simulation ◽  
Injection Pressure ◽  
Transient Operation ◽  
Load Spectrum ◽  
Two Phase ◽  
Transient Conditions

Available correlations for the ignition delay in pulsating, turbulent, two-phase, reacting mixtures found in a diesel engine often have limited predictive ability, especially under transient conditions. This study focuses on the development of an ignition delay correlation, based on engine data, which is suitable for predictions under both steady-state and transient conditions. Ignition delay measurements were taken on a heavy-duty diesel engine across the engine speed/load spectrum, under steady-state and transient operation. The dynamic start of injection was calculated by using a skip-fire technique to determine the dynamic needle lift pressure from a measured injection pressure profile. The dynamic start of combustion was determined from the second derivative of measured cylinder pressure. The inferred ignition delay measurements were correlated using a modified Arrhenius expression to account for variations in fuel/air composition during transients. The correlation has been compared against a number of available correlations under steady-state conditions. In addition, comparisons between measurements and predictions under transient conditions are made using the extended thermodynamic simulation framework of Assanis and Heywood. It is concluded that the proposed correlation provides better predictive capability under both steady-state and transient operation.

A Numerical Study of Concurrent Flame Propagation Over Methanol Pool Surface

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Seik Mansoor Ali ◽  
Vasudevan Raghavan ◽  
K. Velusamy ◽  
Shaligram Tiwari
Keyword(s):  
Flame Spread ◽  
Numerical Study ◽  
Leading Edge ◽  
Reacting Flow ◽  
Atmospheric Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Spread Velocity ◽  
Pool Surface ◽  
Initial Flame

Concurrent flame spread over methanol pool surface under atmospheric conditions and normal gravity has been numerically investigated using a transient, two-phase, reacting flow model. The average flame spread velocities for different concurrent air velocities predicted using the model are quite close to the experimental data available in the literature. As the air velocity is increased, the fuel consumption rate increases and aids in faster flame spread process. The flame initially anchors around the leading edge of the pool and the flame tip spreads over the pool surface. The rate of propagation of flame tip along the surface is seen to be steady without fluctuations. The flame spread velocity is found to be nonuniform as the flame spreads along the pool surface. The flame spread velocity is seen to be higher initially. It then decreases up to a point when the flame has propagated to around 40% to 50% of the pool length. At this position, a secondary flame anchoring point is observed, which propagates toward the trailing edge of the pool. As a result, there is an increasing trend observed in the flame spread velocity. As the air velocity is increased, the initial flame anchoring point moves downstream of the leading edge of the fuel pool. The variations of interface quantities depend on the initial flame anchoring location and the attainment of thermodynamic equilibrium between the liquid- and gas-phases.

Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor

2014 ◽  
Author(s):  
Cheng Huang ◽  
Rohan Gejji ◽  
William Anderson ◽  
Changjin Yoon ◽  
Venkateswaran Sankaran
Keyword(s):  
Gas Turbine ◽  
Direct Injection ◽  
Single Element ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
Lean Direct Injection

scholarly journals Vortex breakdown of the swirling flow in a Lean Direct Injection burner

2020 ◽  
Vol 32 (12) ◽  
pp. 125118
Author(s):  
Yazhou Shen ◽  
Mohamad Ghulam ◽  
Kai Zhang ◽  
Ephraim Gutmark ◽  
Christophe Duwig
Keyword(s):  
Vortex Breakdown ◽  
Swirling Flow ◽  
Direct Injection ◽  
Lean Direct Injection ◽  
Injection Burner

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

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