Journal articles on the topic 'Airblast atomiser design'
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1
Rizk, N. K., and H. C. Mongia. "Calculation Approach Validation for Airblast Atomizers." Journal of Engineering for Gas Turbines and Power 114, no. 2 (April 1, 1992): 386–94. http://dx.doi.org/10.1115/1.2906603.
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In order to formulate a common approach that could provide the spray parameters of airblast atomizers, various processes of liquid preparation, breakup, and secondary atomization have been included in a semi-analytical calculation procedure. The air velocity components in the atomizer flow field are provided by mathematical expressions, and the spray droplets are considered to form at ligament breakup through a disturbance wave growth concept. The validation of the developed approach included the application to six atomizers that significantly varied in concept, design, and size. They represented both prefilming and plain-jet types, and the data utilized in the present effort were obtained with six different liquids. Satisfactory agreement between the measurements and the predictions has been achieved under wide ranges of air/fuel ratio and air pressure drop for various test liquids. The results of this investigation indicate the potential of using such an approach in the early phases of airblast atomizer design, and may be followed by more detailed calculations using analytical tools.
2
Topal, Ahmet, Onder Turan, and Sıtkı Uslu. "Design, Manufacturing and Rig Test of a Small Turbojet Engine Combustor with Airblast Atomizer." International Journal of Materials, Mechanics and Manufacturing 3, no. 2 (2015): 97–100. http://dx.doi.org/10.7763/ijmmm.2015.v3.174.
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Tsai, S. C., and B. Viers. "Airblast Atomization of Viscous Newtonian Liquids Using Twin-Fluid Jet Atomizers of Various Designs." Journal of Fluids Engineering 114, no. 1 (March 1, 1992): 113–18. http://dx.doi.org/10.1115/1.2909985.
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Airblast atomization of viscous Newtonian liquids is carried out using coaxial twin-fluid jet atomizers of different nozzle sizes, slit angles, and slit cross sections for air flow. As the atomizing air swirls downstream along the liquid jet, waves form on the surface of the liquid jet. As a result, the liquid jet sheds ligaments which rapidly collapse into small drops. The atomized drop sizes can be described in terms of three dimensionless groups, namely, liquid-to-air mass ratio (M˙L/M˙A), Weber number (We), and Ohnesorge number (Z) in simple forms whose exponents and coefficients are determined by the best least square fit to the experimental results using the generalized inverse method. In addition, we found that the atomized drop sizes substantially decrease as the atomizing air pressure exceeds a threshold value which varies from less than 170 to 220 kPa depending on the nozzle size and the slit cross section.
4
Rizk, N. K., J. S. Chin, and M. K. Razdan. "Modeling of Gas Turbine Fuel Nozzle Spray." Journal of Engineering for Gas Turbines and Power 119, no. 1 (January 1, 1997): 34–44. http://dx.doi.org/10.1115/1.2815559.
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Satisfactory performance of the gas turbine combustor relies on the careful design of various components, particularly the fuel injector. It is, therefore, essential to establish a fundamental basis for fuel injection modeling that involves various atomization processes. A two-dimensional fuel injection model has been formulated to simulate the airflow within and downstream of the atomizer and address the formation and breakup of the liquid sheet formed at the atomizer exit. The sheet breakup under the effects of airblast, fuel pressure, or the combined atomization mode of the airassist type is considered in the calculation. The model accounts for secondary breakup of drops and the stochastic Lagrangian treatment of spray. The calculation of spray evaporation addresses both droplet heat-up and steady-state mechanisms, and fuel vapor concentration is based on the partial pressure concept. An enhanced evaporation model has been developed that accounts for multicomponent, finite mass diffusivity and conductivity effects, and addresses near-critical evaporation. The presents investigation involved predictions of flow and spray characteristics of two distinctively different fuel atomizers under both nonreacting and reacting conditions. The predictions of the continuous phase velocity components and the spray mean drop sizes agree well with the detailed measurements obtained for the two atomizers, which indicates the model accounts for key aspects of atomization. The model also provides insight into ligament formation and breakup at the atomizer exit and the initial drop sizes formed in the atomizer near field region where measurements are difficult to obtain. The calculations of the reacting spray show the fuel-rich region occupied most of the spray volume with two-peak radial gas temperature profiles. The results also provided local concentrations of unburned hydrocarbon (UHC) and carbon monoxide (CO) in atomizer flowfield, information that could support the effort to reduce emission levels of gas turbine combustors.
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Chong, Cheng Tung, and Simone Hochgreb. "Spray Characteristics of an Internal-Mix Airblast Atomizer." Applied Mechanics and Materials 629 (October 2014): 125–30. http://dx.doi.org/10.4028/www.scientific.net/amm.629.125.
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Detailed characterisation of spray atomization of an injector is important for combustor design and modelling. In this paper, the effects of air/fuel mass ratio on the spray characteristics of an internal-mix airblast atomizer were examined. Distribution of the spatial mean droplet axial velocity and size were measured simultaneously using a phase Doppler anemometry (PDA). In general, small droplets are distributed at the center of the spray with maximum velocity. The droplet size increases with increasing radial distance from the spray centreline, but the drop velocity decreases to a minimum at the spray edge. Increasing the atomizing air/fuel mass ratio reduces fuel droplet size due to increased shear.
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Burby, Martin, Ghasem G. Nasr, Andrew J. Yule, and Leigh Morgan. "SINGLE-PHASE AERODYNAMIC FLOW FIELD VALIDATION OF NOVEL AIRBLAST ATOMIZER DESIGNS." Atomization and Sprays 20, no. 7 (2010): 565–79. http://dx.doi.org/10.1615/atomizspr.v20.i7.10.
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Hoshino, A., T. Sugimoto, T. Tatsumi, and Y. Nakagawa. "Development of a 30PS Class Small Gas Turbine and Its Power-Up Version." Journal of Engineering for Gas Turbines and Power 111, no. 2 (April 1, 1989): 225–31. http://dx.doi.org/10.1115/1.3240240.
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Due to the recent popularity of small and medium-sized industrial gas turbines in many fields, gas turbines below 100 SHP have been employed as prime movers, a power range traditionally reserved for diesel and gasoline engines. Generally speaking, however, small gas turbines have many design difficulties in thermal efficiency, high rotational speed, compact auxiliary equipment, etc., derived from limitations of their dimensions. Small gas turbines S5A-01 and S5B-01, which have 32 PS output power at standard conditions, have been developed and are being produced. Presently, a 30 percent growth rated power producer for S5A-02 and S5B-02 gas turbines is under development. These engines’ configurations are as follows: single-stage centrifugal compressor; single-stage radial turbine; single can combustor; hybrid fuel nozzle with pressure atomizer and airblast atomizer; fuel control valve with pulse width modulation system; electric motor drive fuel pump. In this paper, the authors describe the design features and development history of the base engine and the experimental results with the growth rated version.
8
Eckstein, J., E. Freitag, C. Hirsch, T. Sattelmayer, R. von der Bank, and T. Schilling. "Forced Low-Frequency Spray Characteristics of a Generic Airblast Swirl Diffusion Burner." Journal of Engineering for Gas Turbines and Power 127, no. 2 (April 1, 2005): 301–6. http://dx.doi.org/10.1115/1.1789515.
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The low-frequency response of the spray from a generic airblast diffusion burner with a design typical of an engine system has been investigated as part of an experimental study to describe the combustion oscillations of aeroengine combustors called rumble. The atomization process was separated from the complex instability mechanism of rumble by using sinusoidal forcing of the air mass flow rate without combustion. Pressure drop across the burner and the velocity on the burner exit were found to follow the steady Bernoulli equation. Phase-locked particle image velocimetry measurements of the forced velocity field of the burner show quasisteady behavior of the air flow field. The phase-locked spray characteristics were measured for different fuel flow rates. Here again quasi-steady behavior of the atomization process was observed. With combustion, the phase-locked Mie-scattering intensity of the spray cone was found to follow the spray behavior measured in the noncombusting tests. These findings lead to the conclusion that the unsteady droplet Sauter mean diameter mean and amplitude of the airblast atomizer can be calculated using the steady-state atomization correlations with the unsteady burner air velocity.
9
Durbin, M. D., and D. R. Ballal. "Studies of Lean Blowout in a Step Swirl Combustor." Journal of Engineering for Gas Turbines and Power 118, no. 1 (January 1, 1996): 72–77. http://dx.doi.org/10.1115/1.2816552.
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The design requirements of a modern gas turbine combustor are increasingly dictated by wide stability limits, short flame length, and uniform mixing. To achieve the best trade-off between these three factors, flame characteristics (length, shape, mixedness), lean blowout (LBO), and optimum combustor configuration should be investigated over a wide range of inner and outer air velocities, inner and outer vane angles, and co- versus counterswirl arrangements. Such an investigation was performed in a step swirl combustor (SSC) designed to simulate the fuel–air mixing pattern in a gas turbine combustor dome fitted with an airblast atomizer. It was found that an increase in the outer vane angle and a decrease in inner air velocity decreased the flame length. LBO was improved when outer flow swirl intensity was increased. An optimum hardware and velocity configuration for the SSC was found for inner swirl = 45 deg, outer swirl = 60 deg, coswirl direction, and inner air velocity = outer air velocity = 16 m/s. This optimum SSC configuration yielded: (i) low values of LBO, (ii) short flame length, (iii) uniformly mixed stable flame, and (iv) little or no variation in these characteristics over the range of operation of SSC. Finally, the co- versus counterswirl arrangements and the operation of the optimized combustor configuration are discussed.
10
Harris, M. M., D. N. Marsh, E. A. Vos, and E. Durkin. "Flex Cycle Combustor Development and Demonstration." Journal of Engineering for Gas Turbines and Power 116, no. 3 (July 1, 1994): 534–41. http://dx.doi.org/10.1115/1.2906852.
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An innovative, “flex-cycle” combustion system has been developed for the Garrett Model 400-1 Integrated Power Unit (IPU), a 425 shp (317 kW) gas turbine engine designed for use on future fighter aircraft. Demonstration of this system required real-time transient operation of the combustor in a full-scale test rig. The transient testing was unique, having been performed with an electronic control, which modulated all combustor operating parameters according to programmed engine component maps, drag curves, fuel schedules, and selected ambient test conditions. The axially injected annular combustor is capable of engine starts in two seconds, as well as producing 200 shp (149 kW) for emergency use at all altitudes up to 50,000 ft (15,240 m). The combustion system is capable of switching operation from the emergency power stored energy (SE) mode to the normal-air breathing (NAB) auxiliary power mode without loss of engine power. The flex-cycle combustor supplies emergency power in the SE mode with a temperature rise of 2200°F (1222°C) and in the NAB mode with a temperature rise of 1600°F (889°C). Specific features that make these requirements possible include air-assisted simplex airblast fuel atomizers with integral check valves, and effusion-cooled combustor liner walls. This paper describes the flex-cycle combustion system design, test methods used, and significant test results. Steady-state performance, in both the SE and NAB operating modes, and real-time transient test results are discussed. The transient testing included rapid starts as well as transitions from the SE to NAB operating regimes.
11
Godavarthi, V., K. Dhivyaraja, R. I. Sujith, and M. V. Panchagnula. "Analysis and classification of droplet characteristics from atomizers using multifractal analysis." Scientific Reports 9, no. 1 (November 7, 2019). http://dx.doi.org/10.1038/s41598-019-52596-6.
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Abstract Atomizers find applications in diverse fields such as agriculture, pharmaceutics and combustion. Among the most commonly found atomizer classes of designs are pressure swirl, airblast and ultrasonic atomizers. However, it has thus far not been possible to identify the class of an atomizer from spray characteristics. We perform multifractal detrended fluctuation analysis on the droplet inter-arrival times, diameters and axial velocities of pressure swirl, airblast and ultrasonic nebulizer sprays to quantify the differences in complexity in the respective signals. We show that the width of the multifractal spectrum of the signals of droplet diameters and the inter-arrival times, measured at the edge of the spray are robust atomizer identifiers. Further, we show the presence of correlations among the droplet diameters which are otherwise considered as random or derived from a log-normal distribution. This study can be further generalized to classify fluid mechanical systems or biological sprays using an appropriately chosen single point measurement in the flow field.
12
Liu, Cunxi, Fuqiang Liu, Yanhui Mao, Yong Mu, and Gang Xu. "Experimental Investigation of Performance of an Air Blast Atomizer by Planar Laser Sheet Imaging Technique." Journal of Engineering for Gas Turbines and Power 136, no. 2 (November 1, 2013). http://dx.doi.org/10.1115/1.4025235.
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It is widely recognized that the fuel-air mixing process is a critical factor in improving combustion efficiency and in minimizing pollutants such as NOx. Enhancement of fuel-air mixing can lead to lower pollutant emissions and greater efficiency. However, swirling flows in lean combustors play the role of fuel-air mixing and flame stability. The complex fluid dynamic phenomena encountered in swirling two-phase flow contribute to the difficulty in complete understanding of the different processes occurring in combustors. Fortunately, optical and laser-based visualization techniques available in our lab are important nonintrusive tools for visualizing flow process, especially for fuel injection and fuel-air mixing. To provide for a better understanding of effects of counter-rotating flow on droplets in atomization process, this study is a detailed characterization of the spray generated by an airblast atomizer by planar laser sheet imaging method. Optical facility for spray diagnostics with fuel planar laser induced fluorescence (fuel-PLIF) method for fuel distribution and particle image velocimetry (PIV) method for the velocity of droplets is used to evaluate the performance of an airblast atomizer. The results show that the performance of secondary atomization is influenced by swirling flow and primary atomization simultaneously; the swirling flow exhibits significant influence on the droplet size and space distribution relative to that of primary atomization. The primary swirling air reopens the spray cone generated by pressure-swirl atomizer, and the secondary swirling air affects the fuel distribution by forming the recirculation zone. The results provide critical information for the design and development of combustion chambers.
13
Puggelli, S., D. Bertini, L. Mazzei, and A. Andreini. "Modeling Strategies for Large Eddy Simulation of Lean Burn Spray Flames." Journal of Engineering for Gas Turbines and Power 140, no. 5 (November 21, 2017). http://dx.doi.org/10.1115/1.4038127.
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Over the last years, aero-engines are progressively evolving toward design concepts that permit improvements in terms of engine safety, fuel economy, and pollutant emissions. With the aim of satisfying the strict NOx reduction targets imposed by ICAO-CAEP, lean burn technology is one of the most promising solutions even if it must face safety concerns and technical issues. Hence, a depth insight on lean burn combustion is required, and computational fluid dynamics can be a useful tool for this purpose. In this work, a comparison in large eddy simulation (LES) framework of two widely employed combustion approaches like the artificially thickened flame (ATF) and the flamelet generated manifold (FGM) is performed using ANSYS fluent v16.2. Two literature test cases with increasing complexity in terms of geometry, flow field, and operating conditions are considered. First, capabilities of FGM are evaluated on a single swirler burner operating at ambient pressure with a standard pressure atomizer for spray injection. Then, a second test case, operated at 4 bar, is simulated. Here, kerosene fuel is burned after an injection through a prefilming airblast atomizer within a corotating double swirler. Obtained comparisons with experimental results show different capabilities of ATF and FGM in modeling the partially premixed behavior of the flame and provide an overview of the main strengths and limitations of the modeling strategies under investigation.
14
Nakamura, Sosuke, Vince McDonell, and Scott Samuelsen. "The Effect of Liquid-Fuel Preparation on Gas Turbine Emissions." Journal of Engineering for Gas Turbines and Power 130, no. 2 (February 29, 2008). http://dx.doi.org/10.1115/1.2771564.
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The emissions of liquid-fuel fired gas turbine engines are strongly affected by the fuel preparation process that includes atomization, evaporation, and mixing. In the present paper, the effects of fuel atomization and evaporation on emissions from an industrial gas turbine engine were investigated. In the engine studied, the fuel injector consists of a coaxial plain jet airblast atomizer and a premixer which consists of a cylindrical tube with four mixing holes and swirler slits. The goal of this device is to establish a fully vaporized, homogeneous fuel/air mixture for introduction into the combustion chamber and the reaction zone. In the present study, experiments were conducted at atmospheric pressure and room temperature as well as at actual engine conditions (0.34MPa, 740K) both with and without the premixer. Measurements included visualization, droplet size, and velocity. By conducting tests with and without the premixing section, the effect of the mixing holes and swirler slit design on atomization and evaporation was isolated. The results were also compared with engine data and the relationship between premixer performance and emissions was evaluated. By comparing the results of tests over a range of pressures, the viability of two scaling methods was evaluated with the conclusion that spray angle correlates with fuel to atomizing air momentum ratio. For the injector studied, however, the conditions resulting in superior atomization and vaporization did not translate into superior emissions performance. This suggests that, while atomization and the evaporation of the fuel are important in the fuel preparation process, they are of secondary importance to the fuel/air mixing prior to, and in the early stages of the reaction in, governing emissions.
15
Meier, U., L. Lange, J. Heinze, C. Hassa, S. Sadig, and D. Luff. "Optical Methods for Studies of Self-Excited Oscillations and the Effect of Dampers in a High Pressure Single Sector Combustor." Journal of Engineering for Gas Turbines and Power 137, no. 7 (July 1, 2015). http://dx.doi.org/10.1115/1.4029355.
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Self-excited periodic instabilities in a staged lean burn injector could be forced by operating the combustor at off-design conditions. These pressure oscillations were studied in a high pressure single sector combustor with optical access. Two damper configurations were installed and tested with respect to their damping efficiency in relation to the configuration without dampers. For a variety of test conditions, derived from a part load case, time traces of pressure in the combustor were measured, and amplitudes were derived from their Fourier transformation. These measurements were performed for several combinations of the operating parameters, i.e., injector pressure drop, air/fuel ratio (AFR), pilot/main fuel split, and preheat temperature. These tests “ranked” the respective damper configurations and their individual efficiency with respect to the configuration without dampers. Although a general trend could be observed, the ranking was not strictly consistent for all operating conditions. For several test cases, preferably with pronounced self-excited pressure oscillations, phase-resolved planar optical measurement techniques were applied to investigate the change of spatial structures of fuel, reaction zones, and temperature distributions over a period of an oscillation. A pulsating motion was detected for both pilot and main flame, driven by a pulsating transport of the liquid fuel. This pulsation, in turn, is caused by a fluctuating air velocity, in connection with a prefilming airblast type atomizer. A phase shift between pilot and main injector heat release was observed, corresponding to a shift of fuel penetration. Local Rayleigh indices were calculated qualitatively, based on phase-resolved OH chemiluminescence used as marker for heat release, and corresponding pressure values. This identified regions, where a local amplification of pressure oscillations occurred. These regions were largely identical to the reaction regions of pilot and main injector, whereas the recirculation zone between the injector flows was found to exhibit a damping effect.