Hybrid draft direct-combustion with secondary air jets in cross-flow for reducing CO and PM2.5 emissions in biomass cookstoves

2022 ◽  
Vol 51 ◽  
pp. 101913
Author(s):  
Milind P. Kshirsagar ◽  
Vilas R. Kalamkar
Keyword(s):  
Cross Flow ◽  
Direct Combustion ◽  
Air Jets ◽  
Secondary Air ◽  
Pm2.5 Emissions ◽  
Biomass Cookstoves

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.

Investigation of the Prediction Correlations for the Flow Through Rotating Orifices in the Gas Turbine Secondary Air Flow System

2013 ◽  
Author(s):  
Deoras Prabhudharwadkar ◽  
Zain Dweik ◽  
A. Subramani ◽  
Murali Krishnan R.
Keyword(s):  
Gas Turbine ◽  
Discharge Coefficient ◽  
Flow System ◽  
Air Flow ◽  
Tangential Velocity ◽  
Cross Flow ◽  
Secondary System ◽  
Accurate Analysis ◽  
Secondary Air ◽  
Reliable Design

The secondary air flow system of a gas turbine cools and seals those parts of the turbine which would otherwise be exposed to the high temperatures, resulting in their life reduction or even failures. At the same time, excessive secondary air flow hinders the performance of the engine. Accurate analysis of the secondary system is therefore necessary to safeguard the reliable design of the engine and accurate life predictions. The secondary system is analyzed through the flow network analysis which comprises of chambers or cavities connected through flow passages or restrictions. There are significant number of locations where the air passes through stationary or rotating holes, e.g., the pre-swirl nozzles and the turbine blade receiver holes respectively. The accuracy of the flow prediction depends on the accuracy of the orifice discharge coefficient. This paper provides a detailed assessment of the available discharge coefficient correlations. The discharge coefficient has been found to be dependent on the geometric parameters (viz., length, inlet radius, chamfer), and the amount of cross-flow at the orifice entrance. The cross-flow may result from the relative tangential velocity between the orifice and the air or the inclination of the inlet flow with respect to the orifice axis. In this study, it was found that the discharge coefficient correlations provide similar predictions for flows without any cross-flow. However, significant deviations are seen in the predictions for the cases involving cross-flow. To identify the most accurate correlation for secondary flow application, a thorough assessment was performed using the static and the rotating test data available in the literature. In addition to the comparison using available experimental data, a CFD study was performed to independently assess the correlations. This exercise led to the identification of the most suitable correlation for our application.

Comparison of Discharge Coefficient Measurements and Correlations for Several Orifice Designs With Cross-Flow and Rotation Around Several Axes

2008 ◽  
Author(s):  
M. Hu¨ning
Keyword(s):  
Gas Turbines ◽  
Computer Network ◽  
Cross Flow ◽  
Angular Speed ◽  
Jet Engines ◽  
Component Design ◽  
Engine Design ◽  
Contour Plots ◽  
Secondary Air ◽  
Temperature Levels

Gas turbines and jet engines consist of a network of connected cavities beside the main gas path, called secondary air system. These cavities, which are often surrounded by stationary and high angular speed rotating walls are exposed to varying pressure and temperature levels of air or oil contaminated air and are connected to each other by orifices or restrictors. It is vital to control the secondary flow, to enable a reliable and efficient engine design, which meets component durability with a minimum of parasitic air consumption. It is essential to understand the flow physics as well as network inter-dependency in order to minimise the flow consumption and yet, meeting engine operating requirements, as well as practical parts component design or manufacturing needs. In this connexion computer network codes containing model conceptions, which can accurately predict orifice flows, are essential. In an effort to provide usable further insight into flows across restrictors such as orifices this publication compares test results, CFD calculations and orifice loss calculation models from the open literature with the aid of transformation laws and contour plots. The influence of different geometric features is incorporated into a model for the calculation of discharge coefficients.

Experimental Study on Pressure Losses in Circular Orifices With Inlet Cross Flow

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Daniel Feseker ◽  
Mats Kinell ◽  
Matthias Neef
Keyword(s):  
Experimental Study ◽  
Film Cooling ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Cross Flow ◽  
Pressure Losses ◽  
Wide Range ◽  
Cooling Hole ◽  
Secondary Air

The ability to understand and predict the pressure losses of orifices is important in order to improve the air flow within the secondary air system. This experimental study investigates the behavior of the discharge coefficient for circular orifices with inlet cross flow which is a common flow case in gas turbines. Examples of this are at the inlet of a film cooling hole or the feeding of air to a blade through an orifice in a rotor disk. Measurements were conducted for a total number of 38 orifices, covering a wide range of length-to-diameter ratios, including short and long orifices with varying inlet geometries. Up to five different chamfer-to-diameter and radius-to-diameter ratios were tested per orifice length. Furthermore, the static pressure ratio across the orifice was varied between 1.05 and 1.6 for all examined orifices. The results of this comprehensive investigation demonstrate the beneficial influence of rounded inlet geometries and the ability to decrease pressure losses, which is especially true for higher cross flow ratios where the reduction of the pressure loss in comparison to sharp-edged holes can be as high as 54%. With some exceptions, the chamfered orifices show a similar behavior as the rounded ones but with generally lower discharge coefficients. Nevertheless, a chamfered inlet yields lower pressure losses than a sharp-edged inlet. The obtained experimental data were used to develop two correlations for the discharge coefficient as a function of geometrical as well as flow properties.

scholarly journals Temperature Profile Development in Turbulent Mixing of Coolant Jets With a Confined Hot Cross Flow

1983 ◽  
Author(s):  
S. L. K. Wittig ◽  
O. M. F. Elbahar ◽  
B. E. Noll
Keyword(s):  
Temperature Profile ◽  
Momentum Flux ◽  
Cross Flow ◽  
Field Methods ◽  
Opposite Wall ◽  
Hot Gas ◽  
Air Jets ◽  
Primary Zone ◽  
Exit Temperature ◽  
Wall Injection

The mixing of coolant air jets with the hot gas exiting the primary zone is of major importance to the combustor exit temperature profile. Geometry and momentum flux ratios are the dominant parameters. A theoretical and experimental study of single as well as opposite wall jet injection into a hot cross flow reveals the applicability and limitations of existing correlations. Modified correlations are presented for opposite wall injection with jets of different momentum flux ratios. The advantages in applying field methods for describing the flow are discussed.

Effect of Air-Curtains on Labyrinth Seal Performance

2016 ◽  
Author(s):  
Aakash C. Rai ◽  
Deoras Prabhudharwadkar ◽  
Sunil Murthy ◽  
Andrew Giametta ◽  
David Johns
Keyword(s):  
Gas Turbines ◽  
Cross Flow ◽  
Labyrinth Seal ◽  
Labyrinth Seals ◽  
Air Curtain ◽  
Baseline Design ◽  
Leakage Flows ◽  
Seal Design ◽  
Parametric Studies ◽  
Secondary Air

Labyrinth seals are used in many key sealing locations in gas turbines to control various leakage flows, e.g., to control the secondary air-flow from the compressor (bypassing the combustor), the turbine inter-stage leakages and blade tip leakages. This study was performed to assess the improvement in the performance of a labyrinth seal by using an air-curtain (cross-flow jet(s)) from the stator. Detailed parametric studies were performed to study the effect of the air-curtain jet pressure, location, and the number of jets on the seal performance with respect to the leakage flow. The analysis was done using 2-dimensional axisymmetric CFD simulations. It was found that in the case of a labyrinth seal with a flat stator (without a honeycomb attached to the stator) the air-curtain design can reduce the seal leakage by about 30% over the baseline seal design without air-curtains. This reduction happened because the air-curtain jet deflected the main seal jet away from the seal clearance. A similar conclusion was also obtained in case of a labyrinth seal with a honeycombed stator. Furthermore, our parametric studies with different air-curtain designs parameters implemented over a honeycombed labyrinth seal showed that the air-curtain jet pressure, location, and the number of jets were crucial factors governing the seal leakage. Amongst the air-curtain designs studied, it was found that implementing three air-curtains in the 1st pocket gave the maximum leakage reduction (by about 50%) over the baseline design.

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.

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
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