Swirler Effects on Passive Control of Combustion Noise and Instability in a Swirl-Stabilized Combustor

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Alex Borsuk ◽  
Justin Williams ◽  
Joseph Meadows ◽  
Ajay K. Agrawal
Keyword(s):  
Bluff Body ◽  
Passive Control ◽  
Flow Direction ◽  
High Strength ◽  
Combustion Noise ◽  
Test Case ◽  
Air Flow Rate ◽  
Cross Sectional ◽  
Porous Inert Media ◽  
Flame Behavior

High strength porous inert media (PIM) placed in the reaction zone of a swirl-stabilized lean-premixed combustor is a passive method of controlling combustion noise and instabilities. In this study, the effect of swirler location and swirl number on combustion without and with PIM has been investigated experimentally, using a methane-fueled quartz combustor at atmospheric pressure. Three axial swirlers were designed with eight vanes, a solid centerbody, and vane angles of 30, 45, and 55 deg to yield calculated swirl numbers of 0.45, 0.78, and 1.10, respectively. Swirler location was varied to obtain recess depth in the premixer tube of 0.0 cm, 2.5 cm, and 5.0 cm. A downstream bluff body was used with the recessed swirlers to stabilize the flame at the dump plane. Experiments were conducted at constant air flow rate of 300 SLPM and equivalence ratios of 0.70, 0.75, and 0.80. PIM annular rings with increasing and decreasing cross-sectional area in the flow direction were tested, referred to as diverging and converging PIM. The performance of each test case is compared by observing the flame behavior and measuring sound pressure level (SPL) with a microphone probe. Results include total SPL and SPL in one-third octave bands. PIM proved effective in mitigating combustion noise and instability for all flush-mounted swirlers with total SPL reductions of up to 7.6 dBA. The effectiveness of the PIM generally improved with increasing equivalence ratio. Combustion instability that occurred within the frequency band centered about 630 Hz was suppressed with both PIM configurations. These results confirm that PIM is an effective method to control combustion noise and instabilities in swirl-stabilized LPM combustion.

Swirler Effects on Passive Control of Combustion Noise and Instability in a Swirl-Stabilzed Combustor

2012 ◽  
Author(s):  
Alex Borsuk ◽  
Justin Williams ◽  
Joseph Meadows ◽  
Ajay K. Agrawal
Keyword(s):  
Bluff Body ◽  
Passive Control ◽  
Flow Direction ◽  
High Strength ◽  
Combustion Noise ◽  
Test Case ◽  
Air Flow Rate ◽  
Cross Sectional ◽  
Porous Inert Media ◽  
Flame Behavior

High strength porous inert media (PIM) placed in the reaction zone of a swirl-stabilized lean-premixed combustor is a passive method of controlling combustion noise and instabilities. In this study, the effect of swirler location and swirl number on combustion without and with PIM has been investigated experimentally, using a methane-fueled quartz combustor at atmospheric pressure. Three axial swirlers were designed with 8 vanes, a solid centerbody, and vane angles of 30, 45, and 55 degrees to yield calculated swirl numbers of 0.45, 0.78, and 1.10, respectively. Swirler location was varied to obtain recess depth in the premixer tube of 0.0 cm, 2.5 cm, and 5.0 cm. A downstream bluff body was used with the recessed swirlers to stabilize the flame at the dump plane. Experiments were conducted at constant air flow rate of 300 SLPM and equivalence ratios of 0.70, 0.75, and 0.80. PIM annular rings with increasing and decreasing cross-sectional area in the flow direction were tested, referred to as diverging and converging PIM. The performance of each test case is compared by observing the flame behavior and measuring sound pressure level (SPL) with a microphone probe. Results include total SPL and SPL in one-third octave bands. PIM proved effective in mitigating combustion noise and instability for all flush-mounted swirlers with total SPL reductions of up to 7.6 dBA. The effectiveness of the PIM generally improved with increasing equivalence ratio. Combustion instability that occurred within the frequency band centered about 630 Hz was suppressed with both PIM configurations. These results confirm that PIM is an effective method to control combustion noise and instabilities in swirl-stabilized LPM combustion.

Passive Control of Noise and Instability in a Swirl-Stabilized Combustor With the Use of High-Strength Porous Insert

2011 ◽  
Author(s):  
Daniel Sequera ◽  
Ajay K. Agrawal
Keyword(s):  
Flow Field ◽  
Passive Control ◽  
Recirculation Zone ◽  
High Strength ◽  
Flame Stabilization ◽  
Combustion Noise ◽  
Mean Flow ◽  
Porous Insert ◽  
Swirl Stabilized Combustion ◽  
Reactant Flow

Swirl-stabilized combustion and porous inert medium (PIM) combustion are two methods that have been used extensively, although independently, for flame stabilization. In this study, the two concepts are combined so that the porous insert serves as a passive device to mitigate combustion noise and instabilities. A properly shaped PIM is placed within the combustor to directly influence the turbulent flow field and vortical and/or shear layer structures associated with the outer recirculation zone and inner recirculation zone. After presenting the concept, the paper provides a conceptual understanding of the changes in the mean flow field caused by the PIM. Combustion experiments were conducted at atmospheric pressure using HfC/SiC coated open-cell foam structures of different pore sizes and shapes. Measurements of sound pressure level (SPL) and CO and NOx emissions were taken for different equivalence ratios and reactant flow rates. Combustion mode and PIM geometry to decrease the SPL are identified. Results show that the porous insert can reduce combustion noise without adversely affecting NOx and CO emissions. Experiments show that the proposed concept can also mitigate combustion instabilities encountered at high reactant flow rate.

Passive Control of Noise and Instability in a Swirl-Stabilized Combustor With the Use of High-Strength Porous Insert

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Daniel Sequera ◽  
Ajay K. Agrawal
Keyword(s):  
Flow Field ◽  
Passive Control ◽  
Recirculation Zone ◽  
High Strength ◽  
Flame Stabilization ◽  
Combustion Noise ◽  
Mean Flow ◽  
Porous Insert ◽  
Swirl Stabilized Combustion ◽  
Reactant Flow

Swirl-stabilized combustion and porous inert medium (PIM) combustion are two methods that have been used extensively, although independently, for flame stabilization. In this study, the two concepts are combined so that the porous insert serves as a passive device to mitigate combustion noise and instabilities. A properly shaped PIM is placed within the combustor to directly influence the turbulent flow field and vortical and/or shear layer structures associated with the outer recirculation zone and inner recirculation zone. After presenting the concept, the paper provides a conceptual understanding of the changes in the mean flow field caused by the PIM. Combustion experiments were conducted at atmospheric pressure using HfC/SiC coated open-cell foam structures of different pore sizes and shapes. Measurements of sound pressure level (SPL) and CO and NOx emissions were taken for different equivalence ratios and reactant flow rates. Combustion mode and PIM geometry to decrease the SPL are identified. The results show that the porous insert can reduce combustion noise without adversely affecting NOx and CO emissions. Experiments show that the proposed concept can also mitigate combustion instabilities encountered at high reactant flow rate.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

scholarly journals Comparative Analysis of Different Mobile LiDAR Mapping Systems for Ditch Line Characterization

2021 ◽  
Vol 13 (13) ◽  
pp. 2485
Author(s):  
Yi-Chun Lin ◽  
Raja Manish ◽  
Darcy Bullock ◽  
Ayman Habib
Keyword(s):  
Flow Direction ◽  
Sediment Accumulation ◽  
Digital Terrain Model ◽  
Vertical Direction ◽  
Point Clouds ◽  
Lidar Data ◽  
Cross Sectional ◽  
Premature Failure ◽  
3D Point Clouds ◽  
Mapping Systems

Maintenance of roadside ditches is important to avoid localized flooding and premature failure of pavements. Scheduling effective preventative maintenance requires a reasonably detailed mapping of the ditch profile to identify areas in need of excavation to remove long-term sediment accumulation. This study utilizes high-resolution, high-quality point clouds collected by mobile LiDAR mapping systems (MLMS) for mapping roadside ditches and performing hydrological analyses. The performance of alternative MLMS units, including an unmanned aerial vehicle, an unmanned ground vehicle, a portable backpack system along with its vehicle-mounted version, a medium-grade wheel-based system, and a high-grade wheel-based system, is evaluated. Point clouds from all the MLMS units are in agreement within the ±3 cm range for solid surfaces and ±7 cm range for vegetated areas along the vertical direction. The portable backpack system that could be carried by a surveyor or mounted on a vehicle is found to be the most cost-effective method for mapping roadside ditches, followed by the medium-grade wheel-based system. Furthermore, a framework for ditch line characterization is proposed and tested using datasets acquired by the medium-grade wheel-based and vehicle-mounted portable systems over a state highway. An existing ground-filtering approach—cloth simulation—is modified to handle variations in point density of mobile LiDAR data. Hydrological analyses, including flow direction and flow accumulation, are applied to extract the drainage network from the digital terrain model (DTM). Cross-sectional/longitudinal profiles of the ditch are automatically extracted from the LiDAR data and visualized in 3D point clouds and 2D images. The slope derived from the LiDAR data turned out to be very close to the highway cross slope design standards of 2% on driving lanes, 4% on shoulders, and a 6-by-1 slope for ditch lines.

scholarly journals Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Chen ◽  
Jinjin Zhang ◽  
Jin Yang ◽  
Feilong Ye
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strength Steel ◽  
High Strength ◽  
Tensile Tests ◽  
Reinforcing Steel ◽  
Test Results ◽  
Cross Sectional ◽  
Steel Bars

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

Strain-Rate Effect on the Tensile Behaviour of High Strength Alloys

2011 ◽  
Vol 82 ◽  
pp. 124-129 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Stefano Bianchi
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Cross Sectional ◽  
Split Hopkinson Tensile Bar ◽  
Wide Range ◽  
First Results

In this paper the first results of the mechanical characterization in tension of two high strength alloys in a wide range of strain rates are presented. Different experimental techniques were used for different strain rates: a universal machine, a Hydro-Pneumatic Machine and a JRC-Split Hopkinson Tensile Bar. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. An increase of the stress at a given strain increasing the strain-rate from 10-3 to 103 s-1, a moderate strain-rate sensitivity of the uniform and fracture strain, a poor reduction of the cross-sectional area at fracture with increasing the strain-rate were shown. Based on these experimental results the parameters required by the Johnson-Cook constitutive law were determined.

Smart Passive Control of Thermoacoustic Instability in a Bluff-Body Stabilized Combustor: A Lagrangian Analysis of Critical Structures

2021 ◽  
Author(s):  
C P Premchand ◽  
Manikandan Raghunathan ◽  
Midhun Raghunath ◽  
K V Reeja ◽  
Sujith R I ◽  
...  
Keyword(s):  
Bluff Body ◽  
Passive Control ◽  
Lagrangian Analysis ◽  
Thermoacoustic Instability

Hot Spline Forming of Ultra-High Strength Steel Gear Drum Using Resistance Heating

2014 ◽  
Vol 622-623 ◽  
pp. 201-206 ◽  
Author(s):  
Kenichiro Mori ◽  
Tomoyoshi Maeno ◽  
Shohei Nakamoto
Keyword(s):  
Deep Drawing ◽  
High Strength Steel ◽  
Side Wall ◽  
High Strength ◽  
Axial Direction ◽  
Resistance Heating ◽  
Sectional Area ◽  
Forming Process ◽  
Cross Sectional ◽  
Ultra High Strength Steel

A hot spline forming process of die-quenched gear drums using resistance heating of a side wall of a cup formed by cold deep drawing and ironing was developed. The side wall having uniform cross-sectional area is resistance-heated by passage of the current in the axial direction, the heated side wall of the drawn cup is ironed and is finally die-quenched. The gear drum was successfully formed and the hardness was between 400 and 500 HV. Not only the formability was improved but also the formed dram was hardly oxidised because of rapid resistance heating.

scholarly journals ANALYTICAL STUDY OF BEHAVIOR OF COLD FORMED STEEL SECTIONS WITH AND WITHOUT PERFORATION UNDER COMPRESSIVE LOADING

2021 ◽  
Vol 5 (9) ◽  
Author(s):  
Majahar M. Baraskar ◽  
Pranil Shetake ◽  
Prof. V. M Bogar ◽  
Dr. Y. M Ghugal
Keyword(s):  
Construction Industry ◽  
Compressive Loading ◽  
Weight Ratio ◽  
High Strength ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Steel Sections ◽  
Cold Formed Steel ◽  
Lower Temperature

Steel is used in construction industry due to its hardness and tensile strength. Cold formed steel is type of steel which is manufactured at lower temperature. Cold form steel became more popular in twentieth century in construction industry due to its high strength to weight ratio and post-buckling strength. The purpose of this study is to study the behavior of cold-formed steel sections of different shapes but of same cross sectional area for compressive loading. Effect of lips within same cross sectional area, effect of perforation and shape stiffener is evaluated on different sections as channel section, Z section and hat section. Eigen value buckling analysis was carried out to on twelve different models to obtain the buckling load and failure pattern. ANSYS WORKBENCH software was used for numerical simulation of sections. I.S. 801:1975 has been taken under consideration wherever required. Based upon the results, optimum section in each of cases as with lips, without lips and perforated amongst all three sections is suggested. Effect of shape stiffeners provided by previous researcher P. Manikandan on solid sections is evaluated to check its suitability with perforated sections.

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