Investigation of a novel jet deflector to avoid slag accumulation around secondary air jets in incinerators and boilers

2002 ◽  
Vol 21 (3) ◽  
pp. 183-195
Author(s):  
G. K. Reynolds ◽  
Yoke R. Goh ◽  
V. Nasserzadeh Sharifi ◽  
Jim Swithenbank
Keyword(s):  
Air Jets ◽  
Secondary Air

scholarly journals Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines

1997 ◽  
Author(s):  
Peter Griebel ◽  
Michael Fischer ◽  
Christoph Hassa ◽  
Eggert Magens ◽  
Henning Nannen ◽  
...  
Keyword(s):  
Research Work ◽  
Nox Formation ◽  
Lean Combustion ◽  
Air Jets ◽  
Primary Zone ◽  
Low Emission ◽  
Measuring Techniques ◽  
Annular Combustor ◽  
High Turbulence ◽  
Secondary Air

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques. Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.

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.

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.

scholarly journals THE INFLUENCE OF OPERATIONAL AND STRUCTURAL PARAMETERS ON THE UNEVENNESS OF THE TEMPERATURE FIELD AT THE OUTLET OF THE GAS TURBINE COMBUSTION CHAMBER

2020 ◽  
pp. 80-87
Author(s):  
Ali Sulaiman ◽  
◽  
Bilal Mingazov ◽  
Yury Aleksandrov ◽  
The Nguyen ◽  
...  
Keyword(s):  
Temperature Field ◽  
Combustion Chamber ◽  
Gas Flow ◽  
Structural Parameters ◽  
Temperature Fields ◽  
Mixing Process ◽  
Operational Parameters ◽  
Air Jets ◽  
Annular Jet ◽  
Secondary Air

Ensuring acceptable temperature field non-uniformity at the outlet of the combustion chamber is a very important requirement that determines the reliability and durability of the turbine. The formation of non-uniformity is determined by the nature of the interaction of the secondary air jets with the gas flow in the flame tube and depends on many factors, both structural and operational parameters. In this paper, we propose to evaluate the non-uniformity of the temperature fields at the outlet of the combustion chamber using a mixing coefficient that determines the quality of mixing jets of secondary air with a gas stream in the mixer. Based on the equation of turbulent diffusion during the flow of an annular jet into a limited space, an analytical dependence is obtained in the work that allows one to calculate the mixing process in the combustion chamber. The connection of the mixing process with the formation of temperature fields is established. Based on this, dependences are obtained for calculating the nonuniformity of temperature fields. Their satisfactory agreement with experimental data was shown. The found dependences allow one to analyze the influence of various parameters on the non-uniformity of temperature fields and accelerate the refinement of the combustion chamber by this parameter. The possibility of predicting the effect of various parameters on the unevenness of temperature fields is shown. The presence of the optimal value of the degree of opening of the mixer is confirmed, at which the minimum value of the unevenness of the temperature field at the outlet of the combustion chamber is achieved. Therefore, the analytical relationships found in the work allow optimizing the design of the mixer in the combustion chamber and the distribution of secondary air in it in order to reduce the unevenness of the temperature fields at the outlet of the combustion chamber.

The Mechanics of Flame and Air Jets

1937 ◽  
Vol 137 (1) ◽  
pp. 11-72 ◽  
Author(s):  
R. F. Davis
Keyword(s):  
Axial Direction ◽  
Flame Length ◽  
Similar Process ◽  
Mean Velocity ◽  
Ignition Point ◽  
Jet Mixing ◽  
Air Jets ◽  
Air Jet ◽  
The Mean ◽  
Secondary Air

Consideration of the conditions existing within the turbulent zone formed by a free disperse jet mixing with fluid at rest surrounding it, leads to the conception of an equation for the mean velocity of the jet in an axial direction. Combining the latter equation with that for the upward drift velocity of the gases in a furnace, an expression is obtained for the trajectory of an overfire, or secondary air jet, projected into the furnace. By a similar process the method is extended to the case of a flame jet, taking into account its acceleration due to buoyancy. The mechanism of combustion is next considered, commencing with an examination of the factors controlling the position of the ignition point in a flame jet, and the derivation of an expression for its location in a powdered-fuel flame. This is followed by the development of a formula for the burning rate of powdered fuel suspended in air, which when combined with that for the mean velocity in a flame jet, enables a relationship to be established between the flame length and the particle size, for the ideal case of a uniform powder. Subsequently, the grading or non-uniform nature of actual powders is taken into account. A method is also described for plotting a flame characteristic, showing the effect of fineness of grinding, turbulence, and burner design on the losses due to unburnt combustible.

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.

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