Influences of Fuel Injection and Air Motion Energy Sources on Fuel-Air Mixing Rates in a D.I. Diesel Combustion System

1996 ◽  
Author(s):  
David J. Timoney ◽  
William J. Smith
Keyword(s):  
Fuel Injection ◽  
Energy Sources ◽  
Diesel Combustion ◽  
Combustion System ◽  
Motion Energy ◽  
Air Mixing ◽  
Mixing Rates ◽  
Air Motion

On the Relative Roles of Fuel Spray Kinetic Energy and Engine Speed in Determining Mixing Rates in D.I. Diesel Engines

1997 ◽  
Vol 119 (1) ◽  
pp. 212-217 ◽  
Author(s):  
W. J. Smith ◽  
D. J. Timoney
Keyword(s):  
Kinetic Energy ◽  
Diesel Engines ◽  
Engine Speed ◽  
Fuel Injection ◽  
Injection System ◽  
Dominant Factor ◽  
Mixing Times ◽  
Air Mixing ◽  
Mixing Rates ◽  
Air Motion

This paper describes an attempt to separate out and to quantify the relative importance of fuel injection characteristics and in-cylinder air motion as factors influencing the rate of fuel-air mixing and of combustion in high-speed D.I. diesel engines, where bulk swirling air motion is absent. Tests on a 121 mm bore × 139 mm stroke, 1.6 liter, single-cylinder engine at constant engine speed reveal substantially shorter fuel-air mixing times as the mean fuel injection kinetic energy (M.I.K.E.) is increased. Also, tests at constant injection kinetic energy but with varying engine speed (involving different fuel injection system builds at each speed) show that fuel-air mixing times are reduced at higher engine speeds. From these trends it is concluded that, while injection kinetic energy is the dominant factor in determining fuel-air mixing rates in D.I. diesels, small-scale turbulent air motions, the intensity and structure of which are related to engine speed, also exert an important influence on the mixing rate.

Investigation of Flow Aerodynamics for Optimal Fuel Placement and Mixing in the Radial Swirler Slot of a Dry Low Emission Gas Turbine Combustion Chamber

2015 ◽  
Vol 138 (5) ◽  
Author(s):  
Festus Eghe Agbonzikilo ◽  
Ieuan Owen ◽  
Suresh Kumar Sadasivuni ◽  
Ronald A. Bickerton
Keyword(s):  
Large Scale ◽  
Fuel Injection ◽  
Orthogonal Design ◽  
Test Facility ◽  
Combustion System ◽  
Mixing Processes ◽  
Baseline Design ◽  
Optimization Study ◽  
Low Emission ◽  
Air Mixing

This paper is concerned with optimizing the fuel–air mixing processes that take place within the radial swirler slot of a dry low emission (DLE) combustion system. The aerodynamics of the flow within the slot is complex and this, together with the placement of the fuel holes with cross injection, controls the mixing of the fuel and air. Computational fluid dynamics (CFD) with the shear stress transport (SST) (k–ω) turbulence model was used for flow and mixing predictions within the radial swirler slot and for conducting a CFD-based design of experiments (DOE) optimization study, in which different parameters related to the fuel injection holes were varied. The optimization study was comprised of 25 orthogonal design configurations in the Taguchi L25 orthogonal array (OA). The test domain for the CFD, and its experimental validation, was a large-scale representation of a swirler slot from the Siemens proprietary DLE combustion system. The DOE study showed that the number of fuel holes, injection hole diameter, and interhole distance are the most influential parameters for determining optimal fuel mixing. Consequently, the optimized mixing configuration obtained from the above study was experimentally tested on an atmospheric test facility. The mixing patterns from experiments at various axial locations across the slot are in good agreement with the mixing predictions from the optimal CFD model. The optimized fuel injection design improved mixing compared with the baseline design by about 60%.

Effect of Multiple Injections on Fuel-Air Mixing and Soot Formation in Diesel Combustion Using Direct Flame Visualization and CFD Techniques

2005 ◽  
Author(s):  
Christos A. Chryssakis ◽  
Dennis N. Assanis ◽  
Sanghoon Kook ◽  
Choongsik Bae
Keyword(s):  
Fuel Injection ◽  
Soot Formation ◽  
Direct Injection ◽  
Injection System ◽  
Diesel Combustion ◽  
Cfd Simulations ◽  
Single Cylinder ◽  
Multiple Injections ◽  
Air Mixing ◽  
Computational Fluid Dynamics Cfd

The main objective of this study is to investigate the effect of pilot-, post- and multiple-fuel injection strategies on fuel-air mixing and emissions formation in diesel combustion, using a combination of experimental observations and Computational Fluid Dynamics (CFD) analysis. The experimental study was carried out on a single-cylinder optical direct-injection diesel engine equipped with a high pressure common rail fuel injection system. The experimental work was supported by CFD simulations on the single-cylinder engine in order to investigate the effect of multiple injections on mixture formation. The limitations of the soot formation model were identified through direct comparisons with experimental flame visualization.

Investigation of Flow Aerodynamics for Optimal Fuel Placement and Mixing in the Radial Swirler Slot of a Dry Low Emission Gas Turbine Combustion Chamber

2015 ◽  
Author(s):  
Festus Eghe Agbonzikilo ◽  
Ieuan Owen ◽  
Suresh Kumar Sadasivuni ◽  
Ronald A. Bickerton
Keyword(s):  
Large Scale ◽  
Fuel Injection ◽  
Orthogonal Design ◽  
Test Facility ◽  
Combustion System ◽  
Original Design ◽  
Mixing Processes ◽  
Low Emission ◽  
Air Mixing ◽  
Computational Fluid Dynamics Cfd

This paper presents the results of a detailed investigation of the fuel-air mixing processes that take place within the radial swirler slot of a dry low emission combustion system. The aerodynamics of the flow within the slot is complex and this, together with the placement of the fuel holes with cross injection, controls the mixing of the fuel and air. Computational fluid dynamics (CFD) with the Shear Stress Transport (k-ω) turbulence model was used for flow and mixing predictions within the radial swirler slot and for conducting a CFD-based Design of Experiments (DOE) optimisation study, in which different parameters related to the fuel injection holes were varied. The optimisation study was comprised of 25 orthogonal design configurations in a Taguchi L25 orthogonal array. The test domain for the CFD, and its experimental validation, was a large-scale representation of a swirler slot from a Siemens proprietary DLE combustion system. The DOE study showed that the number of fuel holes, injection hole diameter and inter-hole distance are the most influential parameters for determining optimal fuel mixing. Consequently, the optimised mixing configuration obtained from the above study was experimentally tested on an atmospheric test facility. The mixing patterns from experiments at various axial locations across the slot are in good agreement with the mixing predictions from the optimal CFD model. The optimised fuel injection design improved mixing compared with the original design by about 60%.

Low-Emissions Technology Development for Auxiliary Power Unit Combustion Systems

2021 ◽  
Author(s):  
Thomas Bronson ◽  
Rudy Dudebout ◽  
Nagaraja Rudrapatna
Keyword(s):  
Gas Turbine ◽  
Power Unit ◽  
Fuel Injection ◽  
Oxides Of Nitrogen ◽  
Combustion System ◽  
Auxiliary Power Unit ◽  
Criteria Pollutants ◽  
Auxiliary Power ◽  
Combustion Systems ◽  
Aircraft Application

Abstract The aircraft Auxiliary Power Unit (APU) is required to provide power to start the main engines, conditioned air and power when there are no facilities available and, most importantly, emergency power during flight operation. Given the primary purpose of providing backup power, APUs have historically been designed to be extremely reliable while minimizing weight and fabrication cost. Since APUs are operated at airports especially during taxi operations, the emissions from the APUs contribute to local air quality. There is clearly significant regulatory and public interest in reducing emissions from all sources at airports, including from APUs. As such, there is a need to develop technologies that reduce criteria pollutants, namely oxides of nitrogen (NOx), unburned hydrocarbons (UHC), carbon monoxide (CO) and smoke (SN) from aircraft APUs. Honeywell has developed a Low-Emissions (Low-E) combustion system technology for the 131-9 and HGT750 family of APUs to provide significant reduction in pollutants for narrow-body aircraft application. This article focuses on the combustor technology and processes that have been successfully utilized in this endeavor, with an emphasis on abating NOx. This paper describes the 131-9/HGT750 APU, the requirements and challenges for small gas turbine engines, and the selected strategy of Rich-Quench-Lean (RQL) combustion. Analytical and experimental results are presented for the current generation of APU combustion systems as well as the Low-E system. The implementation of RQL aerodynamics is well understood within the aero-gas turbine engine industry, but the application of RQL technology in a configuration with tangential liquid fuel injection which is also required to meet altitude ignition at 41,000 ft is the novelty of this development. The Low-E combustion system has demonstrated more than 25% reduction in NOx (dependent on the cycle of operation) vs. the conventional 131-9 combustion system while meeting significant margins in other criteria pollutants. In addition, the Low-E combustion system achieved these successes as a “drop-in” configuration within the existing envelope, and without significantly impacting combustor/turbine durability, combustor pressure drop, or lean stability.

Analysis of Mixture Formation and Flame Development of Diesel Combustion Using a Rapid Compression Machine and Optical Visualization Technique

2013 ◽  
Vol 315 ◽  
pp. 293-298 ◽  
Author(s):  
Amir Khalid ◽  
Bukhari Manshoor
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Emissions ◽  
Combustion Characteristics ◽  
Diesel Combustion ◽  
Rapid Compression Machine ◽  
Mixture Formation ◽  
Optical Visualization ◽  
Flame Development ◽  
Rapid Compression

Mixture formation plays as a key element on burning process that strongly affects the exhaust emissions such as nitrogen oxide (NOx) and Particulate Matter (PM). The reductions of emissions can be achieved with improvement throughout the mixing of fuel and air behavior. Measurements were made in an optically-accessible rapid compression machine (RCM) with intended to simulate the actual diesel combustion related phenomena. The diesel combustion was simulated with the RCM which is equipped with the Denso single-shot common-rail fuel injection system, capable of a maximum injection pressure up to 160MPa. Diesel engine compression process could be reproduced within the wide range of ambient temperature, ambient density, swirl velocity, equivalence ratio and fuel injection pressure. The mixture formation and combustion images were captured by the high speed camera. Analysis of combustion characteristics and observations of optical visualization of images reveal that the mixture formation exhibit influences to the ignition process and flame development. Therefore, the examination of the first stage of mixture formation is very important consideration due to the fuel-air premixing process linked with the combustion characteristics. Furthermore, the observation of a systematic control of mixture formation with experimental apparatus enables us to achieve considerable improvements of combustion process and would present the information for fundamental understanding in terms of reduced fuel consumption and exhaust emissions.

Real-time capable simulation of diesel combustion processes for HiL applications

2017 ◽  
Vol 19 (2) ◽  
pp. 214-229 ◽  
Author(s):  
Daniel Neumann ◽  
Christian Jörg ◽  
Nils Peschke ◽  
Joschka Schaub ◽  
Thorsten Schnorbus
Keyword(s):  
Heat Release ◽  
Real Time ◽  
Fuel Injection ◽  
Combustion Process ◽  
Boost Pressure ◽  
Diesel Combustion ◽  
Main Challenge ◽  
Combustion Properties ◽  
Input Variables ◽  
Improved Model

The complexity of the development processes for advanced diesel engines has significantly increased during the last decades. A further increase is to be expected, due to more restrictive emission legislations and new certification cycles. This trend leads to a higher time exposure at engine test benches, thus resulting in higher costs. To counter this problem, virtual engine development strategies are being increasingly used. To calibrate the complete powertrain and various driving situations, model in the loop and hardware in the loop concepts have become more important. The main effort in this context is the development of very accurate but also real-time capable engine models. Besides the correct modeling of ambient condition and driver behavior, the simulation of the combustion process is a major objective. The main challenge of modeling a diesel combustion process is the description of mixture formation, self-ignition and combustion as precisely as possible. For this purpose, this article introduces a novel combustion simulation approach that is capable of predicting various combustion properties of a diesel process. This includes the calculation of crank angle resolved combustion traces, such as heat release and other thermodynamic in-cylinder states. Furthermore, various combustion characteristics, such as combustion phasing, maximum gradients and engine-out temperature, are available as simulation output. All calculations are based on a physical zero-dimensional heat release model. The resulting reduction of the calibration effort and the improved model robustness are the major benefits in comparison to conventional data-driven combustion models. The calibration parameters directly refer to geometric and thermodynamic properties of a given engine configuration. Main input variables to the model are the fuel injection profile and air path–related states such as exhaust gas recirculation rate and boost pressure. Thus, multiple injection event strategies or novel air path control structures for future engine control concepts can be analyzed.

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