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Book Structure Stability and Emissions of Lean Direct Injection Combustion Including a Novel Multi point Ldi System for Nox Reduction

Download or read book Structure Stability and Emissions of Lean Direct Injection Combustion Including a Novel Multi point Ldi System for Nox Reduction written by Rodrigo Villalva Gómez and published by . This book was released on 2013 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental research on lean direct injection (LDI) combustors for gas turbine applications is presented. LDI combustion is an alternative to lean premixed combustion which has the potential of equivalent reduction of oxides of nitrogen (NOx) emissions and of peak combustor exit temperatures, but without some drawbacks of premixed combustors, such as flashback and autoignition. Simultaneous observations of the velocity field and reaction zone of an LDI swirl-stabilized combustor with a mixing tube at atmospheric conditions, with the goal of studying the flame stabilization mechanism, are shown. The flame was consistently anchored at the shear layer formed by the high-speed reactants exiting the mixing tube and the low speed recirculation region. Individual image analysis of the location of the tip of the recirculation zone and tip of the reaction region confirmed previously observed trends, but showed that calculation of the distance between these two points for corresponding image pairs yields results no different than when calculated from random image pairs. This most likely indicates a lag in the anchoring of the flame to changes in the recirculation zone, coupled with significant stochastic variation. An alternate LDI approach, multi-point LDI (MLDI), is also tested experimentally. A single large fuel nozzle is replaced by multiple small fuel nozzles to improve atomization and reduce the total volume of the high-temperature, low velocity recirculation zones, reducing NOx formation. The combustor researched employs a novel staged approach to allow good performance across a wide range of conditions by using a combination of nozzle types optimized to various power settings. The combustor has three independent fuel circuits referenced as pilot, intermediate, and outer. Emissions measurements, OH* chemiluminescence imaging, and thermoacoustic instability studies were run in a pressurized combustion facility at pressures from 2.0 to 5.3 bar.Combustor performance was analyzed for three fuel staging configurations, using local equivalence ratio of the individual circuits as a predictive parameter. Pilot-only mode enabled combustor operation at very low overall equivalence ratios while limiting NOx formation in idle power settings due to its configuration approximating a rich-quench-lean combustor. Pilot and intermediate staging tests demonstrated the range of equivalence ratios that are effective in reducing NOx formation while keeping other pollutants in check; very low equivalence ratio results in high unburned hydrocarbon and carbon monoxide, while very high equivalence ratios result in a detrimental effect as more fuel is routed through the intermediate fuel circuit. Using all three fuel circuits simultaneously in high power operation resulted in very low NOx levels (emissions index at or below 0.5 g/kg), particularly when fuel distribution was such that local equivalence ratio was equal among all circuits. The observed NOx levels compared favorably with other MLDI designs which do not have the operational flexibility of the combustor tested. Thermoacoustic instabilities occurred in the MLDI combustor for some test conditions. The local equivalence ratio of the intermediate fuel circuit was found to be one of the major predictor of the onset of instabilities. Detailed analysis of a two-circuit instability (pilot and intermediate) is presented.

Book Numerical Analysis of Non reacting Flow in a Multi nozzle Swirl Stabilized Lean Direct Injection Combustor

Download or read book Numerical Analysis of Non reacting Flow in a Multi nozzle Swirl Stabilized Lean Direct Injection Combustor written by Ritangshu Giri and published by . This book was released on 2015 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multipoint lean direct injection (MLDI) concept was introduced recently in non-premixed combustion to obtain both low NOx emissions and good combustion stability. In this concept a key feature is the injection of finely atomized fuel into high swirling airflow at the combustor dome that provides a homogenous, lean fuel-air mixture. In order to achieve fine atomization and mixing of fuel and air quickly and uniformly, a well designed swirler system is imperative. The present study aims to investigate non-reacting aerodynamic flow characteristics in one such swirl stabilized multiple lean direct injection (MLDI) nozzle system, using the capabilities of computational fluid dynamics (CFD). The fuel nozzles were designed and provided by United Technologies Aerospace Systems (UTAS). The commercial CFD solver Fluent (Ansys Inc, USA) is incorporated to solve the 3-D Navier-Stokes equations for different CFD numerical formulations and, hence simulate the turbulent swirling flowfield generally associated with such systems. Two separate studies were conducted. The first study analyzed the effect of swirl on a turbulent flowfield in a rectangular chamber with sudden expansion, where the complex nozzle system housing air swirlers and a fuel injector were replaced by simple cylindrical inlets. The second study investigated typical aerodynamic flow features associated with the actual system. The domain for conducting simulations were the entire geometry in both cases. First a trusted grid is developed by carrying out grid refinement analysis for both studies. Then a comparison of different Reynolds-Averaged Navier Stokes (RANS) turbulence model were carried out for both cases. The time averaged Particle Image Velocimetry (PIV) data was used as a basis of comparison and the model most closely matching those values was finalized for further numerical computations. Steady state was employed for both set of problems. For the first problem, different swirl intensities were incorporated at the cylindrical inlet to study the changing structure of flowfield. The second numerical analysis of the actual geometric model was further subdivided into two sections. The first section studied the flowfield changes in this complex model by incorporating different mass flow rates for the same nozzle spacing of S = 1.36d. The solution captures the essential flow features generally associated with a non-reacting swirling flowfield in a LDI combustor. The second section analyzed the change in flowfield structure when the spacing between nozzles were varied from 1.1d to 2.72d. A single nozzle case was also used as a basis for comparison. The results obtained were also compared to the available time averaged PIV data. The effect of inter-nozzle spacing result in flows, where the nozzles interact strongly to a case where nozzles do not interact atleast for most of the axial locations. Thus the results provide a useable CFD model for evaluation of this flowfield while highlighting their areas of uncertainty. In addition to that, they also provide useful prerequisites for conducting further reacting flow analysis for this particular design.

Book Fuel Injector Patternation Evaluation in Advanced Liquid Fueled High Pressure Gas Turbine Combustors Using Nonintrusive Optical Diagnostic Techniques

Download or read book Fuel Injector Patternation Evaluation in Advanced Liquid Fueled High Pressure Gas Turbine Combustors Using Nonintrusive Optical Diagnostic Techniques written by and published by . This book was released on 1998 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flow Characteristics in Lean Direct Injection Combustors

Download or read book Flow Characteristics in Lean Direct Injection Combustors written by Dipanjay Dewanji and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Ceramic Integration and Joining Technologies

Download or read book Ceramic Integration and Joining Technologies written by Mrityunjay Singh and published by John Wiley & Sons. This book was released on 2011-10-11 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book joins and integrates ceramics and ceramic-based materials in various sectors of technology. A major imperative is to extract scientific information on joining and integration response of real, as well as model, material systems currently in a developmental stage. This book envisions integration in its broadest sense as a fundamental enabling technology at multiple length scales that span the macro, millimeter, micrometer and nanometer ranges. Consequently, the book addresses integration issues in such diverse areas as space power and propulsion, thermoelectric power generation, solar energy, micro-electro-mechanical systems (MEMS), solid oxide fuel cells (SOFC), multi-chip modules, prosthetic devices, and implanted biosensors and stimulators. The engineering challenge of designing and manufacturing complex structural, functional, and smart components and devices for the above applications from smaller, geometrically simpler units requires innovative development of new integration technology and skillful adaptation of existing technology.

Book Experimental Investigation of a Multiplex Fuel Injector Module with Discrete Jet Swirlers for Low Emission Combustors

Download or read book Experimental Investigation of a Multiplex Fuel Injector Module with Discrete Jet Swirlers for Low Emission Combustors written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A low-NOx emissions combustor concept has been demonstrated in flame-tube tests. A lean-direct injection (LDI) concept was used where the fuel is injected directly into the flame zone and the overall equivalence ratio of the mixture is lean. The LDI concept described in this report is a multiplex fuel injector module containing multipoint fuel injection tips and multi-burning zones. The injector module comprises 25 equally spaced injection tips within a 76 by 76 mm area that fits into the flame-tube duct. The air swirlers were made from a concave plate on the axis of the fuel injector using drilled holes at an angle to the axis of the fuel injector. The NOx levels were quite low and are greater than 70 percent lower than the 1996 ICAO standard. At an inlet temperature of 810 K, inlet pressure of 2760 kPa, pressure drop of 4 percent and a flame temperature of 1900 K with JP8 fuel, the NOx emission index was 9. The 25-point injector module exhibited the most uniform radial distribution of fuel-air mixture and NOx emissions in the flame tube when compared to other multipoint injection devices. A correlation is developed relating the NOx emissions to inlet temperature, inlet pressure, equivalence ratio and pressure drop. Tacina, Robert and Mao, Chien-Pei and Wey, Changlie Glenn Research Center NASA/TM-2004-212918, AIAA Paper 2004-0185, E-14358

Book Fuel Injector Air Swirl Characterization Aerothermal Modeling Phase 2 Volume 1

Download or read book Fuel Injector Air Swirl Characterization Aerothermal Modeling Phase 2 Volume 1 written by and published by . This book was released on 1993 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Lean Direct Injection Diffusion Tip and Related Method

Download or read book Lean Direct Injection Diffusion Tip and Related Method written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A nozzle for a gas turbine combustor includes a first radially outer tube defining a first passage having an inlet and an outlet, the inlet adapted to supply air to a reaction zone of the combustor. A center body is located within the first radially outer tube, the center body including a second radially intermediate tube for supplying fuel to the reaction zone and a third radially inner tube for supplying air to the reaction zone. The second intermediate tube has a first outlet end closed by a first end wall that is formed with a plurality of substantially parallel, axially-oriented air outlet passages for the additional air in the third radially inner tube, each air outlet passage having a respective plurality of associated fuel outlet passages in the first end wall for the fuel in the second radially intermediate tube. The respective plurality of associated fuel outlet passages have non-parallel center axes that intersect a center axis of the respective air outlet passage to locally mix fuel and air exiting said center body.

Book Aerodynamics of Lean Direct Injection Combustor with Multi swirler Arrays

Download or read book Aerodynamics of Lean Direct Injection Combustor with Multi swirler Arrays written by and published by . This book was released on 2006 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flow Characteristics of Gas blast Fuel Injectors for Direct injection Compression ignition Engines

Download or read book Flow Characteristics of Gas blast Fuel Injectors for Direct injection Compression ignition Engines written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural gas has a high auto-ignition temperature, therefore natural gas engines use an ignition source to promote combustion. The high-pressure direction-injection (HPDI) systems available use small diesel injections prior to the main gas injection. A new series of HPDI injectors have been developed that inject diesel and gas simultaneously through the same holes. In order to understand and control injection and combustion behavior in an engine, it is essential to understand how injection mass is related to the diesel/gas ratio and injection command parameters. Three prototype injectors are examined. "Prototype B" most closely resembles a standard J36 HPDI injector, but has a modified diesel needle that injects diesel internally into a common diesel/gas reservoir. Prototypes "CS & CSX" have the diesel needle eliminated and replaced with a flow restrictor. The pressure difference between the diesel and the gas controls the quantity of diesel injected. A single pulse width (GPW) for the gas needle controls the fuel quantities. An injection visualization chamber (IVC) was developed for flow measurements and optical characterization of injections into a chamber at pressures up to 80 bar. Diesel and natural gas are replaced by VISCOR® and nitrogen to study non-reacting flows. A novel feature of the IVC is a retracting shroud that allows the injector to reach steady-state prior to imaging. For low commanded injection duration (GPW less than 0.60 ms), the relation between GPW and injected mass is non-linear, for all injectors tested. For gas pulse widths greater than 0.65 ms the Co-injectors exhibit approximately linear behavior with higher diesel fuelling quantities lowering gas flow quantities. All Co-injectors are compared to baseline gas flow quantities of a standard J36 to show design difference effects on flow quantities. The sensitivity of gas flow to diesel in injection quantities, as well as the discharge coefficient are computed and theoretically modeled for each.

Book CHARACTERIZATION OF THE POST INJECTION BEHAVIOR OF GASOLINE DIRECT INJECTION FUEL INJECTORS

Download or read book CHARACTERIZATION OF THE POST INJECTION BEHAVIOR OF GASOLINE DIRECT INJECTION FUEL INJECTORS written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : The characteristics of gasoline sprayed directly into combustion chambers are of critical importance to engine out emissions and combustion system development. The optimization of the spray characteristics to match the in-cylinder flow field, chamber geometry, and spark location are vital tasks during the development of an engine combustion strategy. Furthermore, the presence of liquid fuel during combustion in Spark-Ignition (SI) engines causes increased hydrocarbon (HC) emissions [1]. Euro 6, LEVIII, and US Tier 3 emissions regulations reduce the allowable particulate mass significantly from the previous standards. LEVIII standards reduce the acceptable particulate emission to 1 mg/mile [2]. A good Direct Injection Spark Ignited (DISI) strategy vaporizes the correct amount of fuel at the proper point in the engine cycle with the proper in-cylinder air flow for optimal power output with minimal emissions. The opening and closing phases of DISI injectors is crucial to this task as the spray produces larger droplets during both theses phases. This work focuses on the results from a novel method to investigate fuel behavior upon closing of the fuel injector. A Design of Experiments (DOE) was used to determine the effect of pressure, temperature, and pulse-width of the fuel spray after the closing event. Experiments determined that the primary source of controlling the droplet size and the mass post injector closing for a given injector was the temperature. It was found that the end of injection behavior is a highly dynamic, complex event including, but not limited to, effects from the injector design, deposit concentration, and fuel type.