RAMJET TECHNOLOGY. CHAPTER 7. AIR-FUEL MIXTURE PREPARATION

1952 ◽  
Author(s):  
J. P. LONGWELL ◽  
M. A. WEISS
Keyword(s):  
Fuel Mixture ◽  
Mixture Preparation

Dual-Location Fuel Injection Effects on Emissions and NO*/OH* Chemiluminescence in a High Intensity Combustor

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Ahmed O. Said ◽  
Ahmed E. E. Khalil ◽  
Ashwani K. Gupta
Keyword(s):  
Fuel Injection ◽  
Single Injection ◽  
Mixing Time ◽  
Fuel Mixture ◽  
Combustion Noise ◽  
Fuel Distribution ◽  
Mixture Preparation ◽  
Pollutants Emission ◽  
Fuel Mixing ◽  
Colorless Distributed Combustion

Colorless distributed combustion (CDC) has shown to provide ultra-low emissions of NO, CO, unburned hydrocarbons, and soot, with stable combustion without using any flame stabilizer. The benefits of CDC also include uniform thermal field in the entire combustion space and low combustion noise. One of the critical aspects in distributed combustion is fuel mixture preparation prior to mixture ignition. In an effort to improve fuel mixing and distribution, several schemes have been explored that includes premixed, nonpremixed, and partially premixed. In this paper, the effect of dual-location fuel injection is examined as opposed to single fuel injection into the combustor. Fuel distribution between different injection points was varied with the focus on reaction distribution and pollutants emission. The investigations were performed at different equivalence ratios (0.6–0.8), and the fuel distribution in each case was varied while maintaining constant overall thermal load. The results obtained with multi-injection of fuel using a model combustor showed lower emissions as compared to single injection of fuel using methane as the fuel under favorable fuel distribution condition. The NO emission from double injection as compared to single injection showed a reduction of 28%, 24%, and 13% at equivalence ratio of 0.6, 0.7, and 0.8, respectively. This is attributed to enhanced mixture preparation prior to the mixture ignition. OH* chemiluminescence intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream, allowing for longer fuel mixing time prior to ignition. This longer mixing time resulted in better mixture preparation and lower emissions. The OH* chemiluminescence signals also revealed enhanced OH* distribution with fuel introduced through two injectors.

Cold Engine Transient Fuel Control Experiments in a Port Fuel Injected CFR Engine

2007 ◽  
Author(s):  
Leonard J. Hamilton ◽  
Jim S. Cowart
Keyword(s):  
Steady State ◽  
Fuel Mixture ◽  
Operating Regime ◽  
Warm Up ◽  
Flame Ionization ◽  
Mixture Preparation ◽  
Steady State Operation ◽  
Fuel Vaporization ◽  
Unburned Hydrocarbons ◽  
Ionization Detectors

Air-fuel mixture preparation is particularly challenging during cold engine throttle transients due to poor fuel vaporization and transport delays in port fuel injected (PFI) engines. In this study, a PFI Cooperative Fuels Research engine is used to evaluate torque and measure in cylinder and exhaust CO, CO2 and unburned hydrocarbons during throttle transients at various early stages of engine warm-up. Fast flame ionization detectors and non-dispersive infra-red fast CO and CO2 detectors are used to provide detailed cycle-by-cycle analysis. Torque after cold throttle transients is found to be comparable to steady state torque due to allowable spark advance. However, cold transients produce up to 4 times the unburned hydrocarbons when compared to steady state operation. Finally, the x-tau fuel control model is evaluated in this challenging operating regime and is found to provide poor transient fuel control due to excessive fueling.

Role of Fuel Injection Scheme in a High Intensity Combustor

2016 ◽  
Author(s):  
Ahmed O. Said ◽  
Ashwani K. Gupta
Keyword(s):  
Reaction Zone ◽  
Intensity Distribution ◽  
Fuel Injection ◽  
Mixing Time ◽  
Fuel Mixture ◽  
Fuel Distribution ◽  
Mixture Preparation ◽  
Injection Scheme ◽  
Pollutants Emission

Fuel injection at two locations in a combustor using premixed, partially pre-mixed and non-premixed schemes has been explored for improved distributed combustion. The effect of dual location fuel injection to the combustor is examined and the results compared from single fuel injection. Focus of dual and single injection scheme was on enhancing reaction zone uniformity in the combustor. A cylindrical combustor at a combustion intensity of 36MW/m3.atm and heat load of 6.25 kW was used. Three different schemes of dual location fuel injection with different proportions of fuel injected from each injector were investigated using methane as the fuel. The role of fuel distribution between the two injection ports using constant air flow rate to the combustor at room temperature was examined on reaction zone distribution and pollutants emission. Three different equivalence ratios of 0.6, 0.7 and 0.8 were examined with different fuel distributions between the two injectors to the combustor at a constant overall thermal load. The results showed lower emission with dual location fuel injection as compared to single location. Dual location fuel injection showed 48% NO reduction with 90% of the total fuel from injector 1 while only 13% reduction was achieved with 80% of the fuel injection from this location. . OH* Chemiluminescene intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream to allow longer fuel mixture preparation time prior to ignition. The longer mixing time resulted in improved mixture preparation and lower emissions. The OH* Chemiluminescene intensity distribution with fuel introduced through two injectors showed improved OH* distribution in the combustor. Improved mixture preparation enhanced reaction distribution in the combustor and lower emission.

A Computational Study of the Mixture Preparation in a Direct Injection Hydrogen Engine

2014 ◽  
Author(s):  
Jerome Le Moine ◽  
P. K. Senecal ◽  
Sebastian A. Kaiser ◽  
Victor M. Salazar ◽  
Jon W. Anders ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computational Study ◽  
Early Stage ◽  
Direct Injection ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Fuel Mixture ◽  
Compression Stroke ◽  
Mixture Preparation

This paper reports the validation of a three-dimensional numerical simulation of the mixture preparation in a direct-injection hydrogen-fueled engine. Computational results from the commercial code CONVERGE are compared to the experimental data obtained from an optically accessible engine. The geometry used in the simulation is a passenger-car sized, four-stroke, spark-ignited engine. The simulation includes the geometry of the combustion chamber as well as the intake and exhaust ports. The hydrogen is supplied at 100 bar from a centrally located injector with a single-hole nozzle. The comparison between the simulation and experimental data is made on the central vertical plane. The fuel mole concentration and flow field are compared during the compression stroke at different crank angles. The comparison shows good agreement between the numerical and experimental results during the early stage of the compression stroke. The penetration of the jet and the interaction with the cylinder walls are correctly predicted. The fuel spreading is under predicted which results in differences in flow field and fuel mixture during the injection between experimental and numerical results. At the end of the injection, the fuel distribution shows some disagreement which gradually increases during the rest of the simulation.

Cold Engine Transient Fuel Control Experiments in a Port Fuel Injected CFR Engine

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Leonard J. Hamilton ◽  
Jim S. Cowart
Keyword(s):  
Steady State ◽  
Fuel Mixture ◽  
Operating Regime ◽  
Control Model ◽  
Flame Ionization ◽  
Mixture Preparation ◽  
Steady State Operation ◽  
Fuel Vaporization ◽  
Unburned Hydrocarbons ◽  
Ionization Detectors

Air-fuel mixture preparation is particularly challenging during cold engine throttle transients due to poor fuel vaporization and transport delays in port fuel injected (PFI) engines. In this study, a PFI cooperative fuels research engine is used to evaluate torque and to measure in-cylinder and exhaust CO, CO2, and unburned hydrocarbons during throttle transients at various early stages of engine warmup. Fast flame ionization detectors and nondispersive infrared fast CO and CO2 detectors are used to provide a detailed cycle-by-cycle analysis. Ttorque after cold throttle transients is found to be comparable to steady-state torque due to allowable spark advance. However, cold transients produce up to four times the unburned hydrocarbons when compared to steady-state operation. Finally, the x-tau fuel control model is evaluated in this challenging operating regime and is found to provide poor transient fuel control due to excessive fueling.

Parametric Study to Optimize Air/Fuel Mixing for Lean, Premix Combustion Systems

2002 ◽  
Author(s):  
Ibrahim Yimer ◽  
Ian Campbell
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Fuel Mixture ◽  
Statistical Technique ◽  
Gas Temperature ◽  
Physical Processes ◽  
Mixture Preparation ◽  
Premix Combustion ◽  
Planar Laser ◽  
Set Up

New designs of gas turbine combustors for power generation applications have to meet ever-tightening emission standards (mainly NOx, CO and UHC) while operating at high combustor pressures. This requires a detailed understanding of the physical processes involved. The air-fuel mixture preparation is a critical step in most advanced gas turbine combustion strategies to achieve lower emissions. It has long been established that the level of unmixedness between the fuel and air is strongly tied with NOx levels. The present paper applies the statistical technique of Design Of Experiments (DOE) to a generic mixer set-up that includes an axial swirler, with fuel injected at discrete locations and transverse to the flow. The objective is to identify influential design and operating parameters that will provide rapid and enhanced mixing. The parameters tested include Swirl strength as measured by the Swirl number, Swirl type (Constant angle vs. Free vortex), number and momentum of fuel injection sites and gas temperature. Planar Laser Induced Fluorescence of acetone (PLIF) was used to quantify mixing at various planar locations in the mixing section. Commercial CFD software is used to model the flow field and predict the spatial mixing at selected conditions. Comparisons are made with experimental measurements with the aim to validate the CFD code and also on comparing the model results with the measurements.

Study of Air-Fuel Mixture Preparation in a Single Cylinder SI Engine

2010 ◽  
Author(s):  
Balasubramanian Thiruvallur Loganathan ◽  
Shamit Bakshi PhD ◽  
Ghodeswar Dinesh
Keyword(s):  
Fuel Mixture ◽  
Si Engine ◽  
Single Cylinder ◽  
Mixture Preparation

A Computational Study of the Mixture Preparation in a Direct–Injection Hydrogen Engine

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Jerome Le Moine ◽  
P. K. Senecal ◽  
Sebastian A. Kaiser ◽  
Victor M. Salazar ◽  
Jon W. Anders ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computational Study ◽  
Early Stage ◽  
Direct Injection ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Fuel Mixture ◽  
Compression Stroke ◽  
Mixture Preparation

This paper reports the validation of a three-dimensional numerical simulation of the mixture preparation in a direct-injection (DI) hydrogen-fueled engine. Computational results from the commercial code CONVERGE are compared to the experimental data obtained from an optically accessible engine. The geometry used in the simulation is a passenger-car sized, four-stroke, and spark-ignited engine. The simulation includes the geometry of the combustion chamber as well as the intake and exhaust ports. The hydrogen is supplied at 100 bar from a centrally located injector with a single-hole nozzle. The comparison between the simulation and experimental data is made on the central vertical plane. The fuel mole concentration and flow field are compared during the compression stroke at different crank angles (CA). The comparison shows good agreement between the numerical and experimental results during the early stage of the compression stroke. The penetration of the jet and the interaction with the cylinder walls are correctly predicted. The fuel spreading is under predicted which results in differences in flow field and fuel mixture during the injection between experimental and numerical results. At the end of the injection, the fuel distribution shows some disagreement which gradually increases during the rest of the simulation.

Sign in / Sign up

Export Citation Format

Share Document