Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions

2000 ◽  
Author(s):  
Thomas Behrendt ◽  
Martin Carl ◽  
Christian Fleing ◽  
Matthias Frodermann ◽  
Johannes Heinze ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Measurement Techniques ◽  
Nox Reduction ◽  
Mie Scattering ◽  
Isothermal Flow ◽  
Operating Conditions ◽  
Aerospace Research ◽  
Air Jets ◽  
Secondary Air ◽  
German Aerospace

Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6 and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurement and calculation of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, Quantitative Light Scattering, OH* Chemiluminescence and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.

Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions

2000 ◽  
Vol 123 (4) ◽  
pp. 810-816 ◽  
Author(s):  
M. Carl ◽  
T. Behrendt ◽  
C. Fleing ◽  
M. Frodermann ◽  
J. Heinze ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Measurement Techniques ◽  
Nox Reduction ◽  
Mie Scattering ◽  
Isothermal Flow ◽  
Operating Conditions ◽  
Aerospace Research ◽  
Air Jets ◽  
Secondary Air ◽  
German Aerospace

Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6, and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD, and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurements and calculations of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, quantitative light scattering, OH* chemiluminescence, and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.

Experimental Investigation of a RQL Burner With Jet in Cross Flow Fuel Injection: Characterization of the Reacting Flow Field at Realistic Operating Conditions

2019 ◽  
Author(s):  
T. Soworka ◽  
T. Behrendt ◽  
C. Hassa ◽  
J. Heinze ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Cross Flow ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Axial Location ◽  
Primary Zone ◽  
Jet In Cross Flow

Abstract Future rich-burn/quick-quench/lean-burn (RQL) burners for aero engines face the challenge to further reduce the emission of soot. Alternative ways of fuel injection are therefore in the focus of modern RQL combustion systems. This contribution aims to investigate experimentally the influence of fuel injection on the reacting flow field, with the emphasis on soot production in the primary zone. For the test, a Rolls-Royce prototype burner was used in two different configurations which differ only in the axial location of jet in cross flow fuel injection and thereby provoke different ways of fuel atomization. In the upstream configuration the burner features characteristics of a pre-filming airblast atomizer. Whereas with the fuel tip in downstream position solely Jet-in-Cross-Flow fuel atomisation is expected. The burner was tested at realistic aero engine combustor conditions (p30 = 9.28 bar, T30 = 603 K, AFR = 7.6). Several optical measurement techniques were used to characterise the reacting flow field. Their difficult application in a rich burn environment is described briefly. The structure of the reacting flow field is illustrated by Particle-Image-Velocimetry (PIV). Planar Mie scattering and Planar Laser-Induced Fluorescence (PLIF) are used to characterise the placement of liquid and gaseous fuel respectively. The location and structure of heat release zones are captured in terms of OH* and CO2* chemiluminescence. Finally Laser-Induced-Incandescence (LII) is used to obtain three dimensional soot distributions in the primary zone. On this basis 20% less soot was measured for the upstream configuration at the axial location of maximal soot concentration. This remarkable difference could be attributed to the different placement of liquid fuel and the resulting better mixing.

Liquid Fuel Placement and Mixing of Generic Aeroengine Premix Module at Different Operating Conditions

2003 ◽  
Vol 125 (4) ◽  
pp. 901-908 ◽  
Author(s):  
J. Becker ◽  
C. Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

The effect of density differences on the path of jets

1961 ◽  
Vol 263 (1314) ◽  
pp. 340-352 ◽  
Keyword(s):  
Density Ratio ◽  
Operating Conditions ◽  
Turbulent Jet ◽  
Water Model ◽  
Hot Gas ◽  
Gas Jets ◽  
Air Jets ◽  
Buoyancy Forces ◽  
Secondary Air ◽  
Model Technique

A turbulent jet of fluid injected into surroundings of different density, soon diverges from its axis of projection as a result of gravitational or buoyancy forces. This feature is exhibited by hot gas jets, in particular by flames, preheated secondary air jets, and effluent plumes. In this paper a water-model technique is described which has been devised to represent the path taken by such jets. This consists of a large transparent box through which a slow stream of water flows and into which a jet of magnetite slurry is injected, to be photographed against an illuminated background. In the model the jet density is greater than that of the surroundings, but the results apply equally to the case where the density ratio is reversed, by considering the trajectory to be inverted. A method of predicting the axes of the heterogeneous jet systems in terms of the initial velocity, the density ratio, the nozzle diameter and the angle of inclination of the axis of projection, is presented. Predicted axes for a variety of operating conditions are shown to compare favourably with observed values obtained in the water model.

Liquid Fuel Placement and Mixing of a Generic Aeroengine Premix Module at Different Operating Conditions

2002 ◽  
Author(s):  
Julian Becker ◽  
Christoph Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

The Estimation of Nitrogen Oxides Reduction Potential Through Enhanced Heat Release Analysis

2016 ◽  
Author(s):  
Tongyang Gao ◽  
Shui Yu ◽  
Kelvin Xie ◽  
Marko Jeftic ◽  
Meiping Wang ◽  
...  
Keyword(s):  
Heat Release ◽  
Reduction Potential ◽  
Nox Reduction ◽  
Close Correlation ◽  
Operating Conditions ◽  
Nox Emission ◽  
Cylinder Pressure ◽  
Release Analysis ◽  
The Impact ◽  
Engine Cycle

An enhanced heat release analysis method is proposed to investigate the NOx emission reduction potential in diesel low temperature combustion and the combustion of premixed ethanol ignited by diesel injections. The heat release analysis from the in-cylinder pressure is a commonly applied diagnostic tool to gain insights in various aspects of combustion, such as start of combustion, ignition delay, combustion phasing, and combustion duration. However, these parameters are more qualitative than quantitative when they are correlated to engine efficiency and emissions. The results are often inconsistent at different engine operating conditions, such as different intake pressure levels, EGR rates and engine loads. In this work, the authors proposed a new parameter named as peak of combustion acceleration, which is the maximum of the first derivative of the heat release rate over an engine cycle. It was observed that the peak of combustion acceleration had a close correlation with the emissions of smoke and NOx at different engine loads and in the combustion of both diesel LTC and premixed ethanol ignited by diesel injections. With the test engine platform, the NOx emission reduced to lower than 50 ppm when the peak of combustion acceleration was less than 25 for diesel LTC and 35 for premixed ethanol ignited by diesel injections. The detailed cylinder pressure sampling and treatment processes were described in this paper. The impact of cycle to cycle variation in the cylinder pressure on the calculation of the peak of combustion acceleration was discussed. The peak of combustion acceleration and the corresponding engine crank angle from each individual engine cycle were calculated and the statistic performance of these parameters was evaluated. The comparison indicated an acceptable consistency between the results from individual engine cycle and from the averaged engine cycles. The proposed peak of combustion acceleration can be potentially integrated in the engine control as an indication of the NOx reduction potential.

Experimental and Numerical Investigation of Different Flame Types Inside a Laboratory Scale RQL Combustion Chamber

2019 ◽  
Author(s):  
Thomas von Langenthal ◽  
Nikolaos Zarzalis ◽  
Marco Konle
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Thermal Power ◽  
Measurement Techniques ◽  
Flame Structure ◽  
Operating Conditions ◽  
Test Rig ◽  
Combustion Chambers ◽  
Primary Zone ◽  
Secondary Air

Abstract RQL (rich burn, quick quench, lean burn) combustion chambers are common in modern aero engines due to their low NOx emissions and good stability. The rich primary zone leads to lower flame temperatures and in combination with the lack of oxygen, the NOx production is low. The mixing of the secondary air must be quick in order to avoid stoichiometric conditions and at the same time must ensure the oxidation of the soot produced in the fuel rich primary zone to keep soot emissions to a minimum. However, the design of such a combustion chamber is complicated due to the complex interaction between the swirling primary flow and the jets of the secondary airflow. In this paper, we present a new test rig, which was designed to study combustion processes inside RQL combustion chambers at atmospheric conditions. The test rig features liquid kerosene combustion and a realistic quenching zone as well as good access for optical and conventional measurement techniques. For realistic engine like conditions the combustion air is preheated to 600 K and the fuel–air equivalence ratio in the primary combustion zone is set to be between Φ = 1.66 and Φ = 1.25, resulting in an overall thermal power between 80 kW and 110 kW. To get insights into the complex flow field inside the combustion chamber unsteady RANS simulations of both the reacting and the non-reacting case were performed using OpenFOAM. The turbulent flow field was modeled using the k-ω-SST model and the combustion was simulated using the Partially Stirred Reactor model. The experimental investigations showed two stable flame types for the same operating conditions with considerable differences in the visible flame structure and soot radiation. The flow field of both of these flame types were measured using a 1.5 kHz 2D PIV System. The numerical simulations showed good overall agreement with the experimental results but could not represent the change in flame type. In order to understand the underlying effects of the flame change the OH* chemiluminescence was recorded and the two-phase flow near the nozzle exit was investigated. This showed that the change in flame structure might arise due to spray dispersion of the pilot fuel nozzle and the recirculation of the secondary air into the primary zone.

scholarly journals Fundamental Study on Ammonia Low-NOx Combustion Using Two-Stage Combustion by Parallel Air Jets

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 23
Author(s):  
Kenta Kikuchi ◽  
Ryuichi Murai ◽  
Tsukasa Hori ◽  
Fumiteru Akamatsu
Keyword(s):  
Nox Reduction ◽  
Axial Direction ◽  
Two Stage ◽  
Fundamental Study ◽  
Lean Combustion ◽  
Air Jets ◽  
Stage Combustion ◽  
Low Nox Combustion ◽  
Secondary Air ◽  
Air Nozzle

Ammonia, which has advantages over hydrogen in terms of storage and transportation, is increasingly expected to become a carbon-free fuel. However, the reduction of fuel NOx emitted from ammonia combustion is an unavoidable challenge. There is the report that two-stage combustion with parallel independent jets could achieve Low-NOx combustion under ammonia/methane co-firing conditions. In order to further improve NOx reduction, we experimentally evaluated the effects of secondary air nozzle parameters, such as nozzle diameter and nozzle locations, on combustion characteristics in two-stage combustion of ammonia/natural gas co-firing using parallel independent jets. As a result of the experiments under various secondary air nozzle conditions, it was found that under the conditions where NOx was significantly reduced, the peak temperature in the furnace was observed at 300–500 mm in the axial direction from the burner, and then the temperature decreased toward the downstream of the furnace. We assumed that this temperature distribution reflected the mixing conditions of the fuel and secondary air and estimated the combustion conditions in the furnace. It was confirmed that the two-stage combustion was effective in reducing NOx by forming a fuel rich region near the downstream of the burner, and the lean combustion of the unburned portion of the first stage combustion with secondary air. We confirmed that the low NOx effects could be achieved by two-stage combustion using independent jets from the same wall under appropriate combustion and air nozzle conditions.

Next Generation Turbine Testing at DLR

2017 ◽  
Author(s):  
Hans-Jürgen Rehder ◽  
Andreas Pahs ◽  
Martin Bittner ◽  
Frank Kocian
Keyword(s):  
Test Section ◽  
Power Plants ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Calibration Procedure ◽  
Test Facility ◽  
Next Generation ◽  
High Pressure Ratio ◽  
Secondary Air ◽  
German Aerospace

Axial turbines for aircraft engines and power plants have reached a very high level of development. Further improvements, in particular in terms of higher efficiency and reduced number of blades and stages, resulting in higher loads, are possible, but can only be achieved through a better understanding of the flow parameters and a closer connection between experiment and numerical design and simulation. An analysis of future demands from the industry and existing turbine research rigs shows that there appears a need for a powerful turbine test rig for aerodynamic experiments. This paper deals with the development and built up of a new so called Next Generation Turbine Test Facility (NG-Turb) at the German Aerospace Center (DLR) in Göttingen. The NG-Turb is a closed-circuit, continuously running facility for aerodynamic turbine investigations, allowing independent variation of engine relevant Mach and Reynolds numbers. The flow medium (dry air) is driven by a 4-stage radial gear compressor with a high pressure ratio and a wide inlet volume flow range. In a first stage the NG-Turb test section will allow investigations on single shaft turbines up to 2½ stages. In a further expansion stage the NG-Turb will be equipped with a second independent shaft system, then enabling experiments with configurations of high and low (or intermediate) pressure turbines and in particular offering the possibility for investigations at counter rotating turbines. Secondary air for cooling investigations can be provided by auxiliary screw compressors. Mass flow through the Turbine is determined redundantly with an uncertainty of about ±0.3%, using well calibrated Venturi nozzles upstream and downstream of the test section. The operation concept and main design features of the NG-Turb will be described and an overview of the applied standard measurement and data acquisition technics capturing efficiency, traverse data etc. will be given. Thermodynamic cycle calculations have been performed in order to simulate the flow circuit of the NG-Turb and to access whether turbine operating points can be driven within the performance map of the compressor system. Finally the calibration procedure for the Venturi nozzles, which has been conducted during the commissioning phase of the NG-Turb by applying a special calibration test section, is explained and some results will be shown.

Modelling Strategies for Large-Eddy Simulation of Lean Burn Spray Flames

2017 ◽  
Author(s):  
S. Puggelli ◽  
D. Bertini ◽  
L. Mazzei ◽  
A. Andreini
Keyword(s):  
Large Eddy Simulation ◽  
Ambient Pressure ◽  
Nox Reduction ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Lean Burn ◽  
Eddy Simulation ◽  
Flamelet Generated Manifold ◽  
Large Eddy ◽  
Modelling Strategies

During 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 (CFD) 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. Firstly, 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 co-rotating double swirler. Obtained comparisons with experimental results show the different capabilities of ATF and FGM in modelling the partially-premixed behaviour of the flame and provides an overview of the main strengths and limitations of the modelling strategies under investigation.

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