Acoustic Diagnostics Applications in the Study of the Oscillation Combustion in Lean Premixed Pre-Evaporation Combustor

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Zilai Zhang ◽  
Shusheng Zang ◽  
Bing Ge ◽  
Peifeng Sun
Keyword(s):  
Combustion Chamber ◽  
Acoustic Signal ◽  
Working Condition ◽  
Dominant Frequency ◽  
Experimental Result ◽  
Combustion Condition ◽  
Pressure Signal ◽  
Transition Condition ◽  
Lean Premixed ◽  
Air Speed

The paper presents an experimental investigation of the thermoacoustic oscillations detection in a lean premixed pre-evaporation (LPP) combustor using acoustic signals. The LPP model combustion chamber oscillation combustion test platform was designed and built; the thermal parameters signal, the acoustic signal, and the dynamic pressure signal were collected under the steady condition and the transition condition, and been analyzed comparatively. The experimental result shows that, at the same inlet air speed, the dominant frequency of the combustion chamber is proportional to the thermal load, while at the same fuel flow, the main frequency of the combustion chamber does not change with the changing of air speed. In addition, the doubling frequency of the acoustic signal is more obvious than the pressure signals, which show that the interference of the acoustic signal is less. In the transition condition, the pulse energy of the acoustic signal is obviously increased after ignition. The dominant frequency energy increases when the working condition begins to change in the stable to oscillation combustion condition. The dominant frequency energy decreases when the working condition begins to change in the oscillation to stable combustion condition. During the flameout condition, the oscillating energy begins to decay from the high frequency region. For the acoustic signal is less disturbed than the pressure signal and it can obtain the same result with the pressure signal in the oscillation condition and the transition condition, acoustic diagnostic is an auxiliary method for combustion oscillation in LPP combustor.

Acoustic Diagnostics Applications in the Study of the Oscillation Combustion in Lean Premixed Pre-Evaporation Combustor

2017 ◽  
Author(s):  
Zilai Zhang ◽  
Shusheng Zang ◽  
Bing Ge ◽  
Peifeng Sun
Keyword(s):  
Transition State ◽  
Combustion Chamber ◽  
Acoustic Signal ◽  
Working Condition ◽  
Air Flow ◽  
Thermal Parameters ◽  
Combustion Condition ◽  
Main Frequency ◽  
Pressure Signal ◽  
Lean Premixed

The paper presents an experimental investigation of the thermoacoustic oscillations detection in a lean premixed pre-evaporation (LPP) combustor using acoustic signals. The LPP model combustion chamber oscillation combustion test platform was designed and built, and the combustion chamber oscillation combustion conditions of the sound - pressure - thermal parameters contrast experiment was complete. In this experiment, the thermal parameters signal, the acoustic signal and the dynamic pressure signal were collected under the oscillation state and the transition state (ignition condition, stable to the oscillation combustion condition, the oscillation to the stable combustion condition and the flameout condition), and been analyzed comparatively. The experimental result shows that the acoustic signal and pressure signal can reflect the changing of the main frequency in the combustion chamber. That is, at the same inlet air flow, the main frequency of the combustion chamber is proportional to the thermal load, while at the same fuel flow, the main frequency of the combustion chamber does not change with the changing of air flow. In addition, the frequency multiplication of the acoustic signal is more obvious than the pressure signal’s, which show that the interference of the acoustic signal is less, it can clearly reflect the thermoacoustic oscillation in the combustion chamber. In the transition state, the pulse energy of the acoustic signal is obviously increased after ignition. The main frequency energy increases when the working condition begins to change in the stable to the oscillation combustion condition. The main frequency energy decreases when the working condition begins to change in the oscillation to the stable combustion condition. During the flameout condition, the oscillating energy begins to decay from the high frequency region. For the acoustic signal is less disturbed than the pressure signal and it can obtained the same result with the pressure signal in the oscillation state and the transition state, it can replace the pressure signal in the thermoacoustic coupling oscillation analysis of the lean premixed pre-evaporation combustor the lean premixed pre-evaporation combustor.

A Comparison of the Influence of Fuel/Air Unmixedness on NOx Emissions in Lean Premixed, Non-Catalytic and Catalytically Stabilized Combustion

1997 ◽  
Author(s):  
A. Schlegel ◽  
M. Streichsbier ◽  
R. Mongia ◽  
R. Dibble
Keyword(s):  
Combustion Chamber ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Tubular Reactor ◽  
Optical Probe ◽  
Nox Emissions ◽  
Fuel Concentration ◽  
Lean Premixed ◽  
Inlet Conditions ◽  
Over Time

Experimental results on the influence of temporal unmixedness on NOx emissions are presented for both non-catalytic and catalytically stabilized, lean premixed combustion. The test rig used for the experiments consists of a fuel/air mixing section which allows variation of the degree of temporal unmixedness while maintaining a uniform “average over time” concentration profile over the cross section at the inlet to the combustion chamber. The unmixedness is measured as “rms fluctuations in fuel concentration” by an optical probe using laser absorption at 3.39μm over a 9mm gap. “Average over time” measurements are taken with “conventional” suction probe analyzers. The combustion chamber is an insulated, tubular reactor (i.d. 26.4mm). At the inlet to the combustion chamber a honeycomb monolith section is inserted. This monolith is either catalytically active or inactive for catalytically stabilized or non-catalytic combustion respectively. For both modes, the exact same inlet conditions are applied. In catalytically stabilized combustion a fraction of the fuel is consumed within the catalyst and the remaining fuel is burnt in the subsequent homogeneous combustion zone. It is shown that catalytically stabilized combustion yields lower NOx emissions and, more important, that the effect of temporal fuel/air unmixedness on NOx emissions is much smaller than with non-catalytic combustion under identical inlet conditions. Experimental evidence leads to the conclusion, that the catalyst is capable of reducing temporal fluctuations in fuel concentration and/or temperature in the combustion process, thereby preventing excess NOx formation. As a result, the requirements on mixing quality are less stringent when using catalytically stabilized combustion instead of conventional, non-catalytic combustion.

scholarly journals Time-frequency analysis of the Surge Onset in the Centrifugal Blower

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Grzegorz Liskiewicz ◽  
Longin Horodko
Keyword(s):  
Wavelet Transform ◽  
Frequency Analysis ◽  
Continuous Wavelet Transform ◽  
Working Condition ◽  
Continuous Wavelet ◽  
Transient Phase ◽  
Centrifugal Blower ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Pressure Signal

Abstract Time frequency analysis of the surge onset was performed in the centrifugal blower. A pressure signal was registered at the blower inlet, outlet and three locations at the impeller shroud. The time-frequency scalograms were obtained by means of the Continuous Wavelet Transform (CWT). The blower was found to successively operate in four different conditions: stable working condition, inlet recirculation, transient phase and deep surge. Scalograms revealed different spectral structures of aforementioned phases and suggest possible ways of detecting the surge predecessors.

The Application of Optical Rotation Principle in Density of Oil Mist Measuring

2009 ◽  
Vol 16-19 ◽  
pp. 980-984 ◽  
Author(s):  
Jian Wen Chen ◽  
L.B. Jia ◽  
Jin Chun Song ◽  
Zhi Wei Zhang ◽  
C.J. Pang
Keyword(s):  
Working Condition ◽  
Optical Rotation ◽  
Measuring Method ◽  
Detection Methods ◽  
Experimental Result ◽  
Lubrication System ◽  
Median Diameter ◽  
Oil Mist ◽  
Conventional Detection

The density of oil mist in this paper is an important factor of oil mist lubrication technology, according to which the effect of lubrication will be known and from which the study on atomization effect will also benefit. In general, the oil mist density of oil mist lubrication system in working condition is 3-12g/ m3 , the median diameter is 1-3 [1], which is difficult to measure with conventional detection methods. The paper takes advantage of optical rotation principle as a measuring method for density of oil mist and achieves a good experimental result.

On the Performance of Porous Sound Absorbent Ceramic Lining in a Combustion Chamber Test Rig

2013 ◽  
Author(s):  
Hans-Christoph Ries ◽  
Mateus Vieira Carlesso ◽  
Christian Eigenbrod ◽  
Stephen Kroll ◽  
Kurosch Rezwan
Keyword(s):  
Combustion Chamber ◽  
Sound Pressure Level ◽  
Gas Turbines ◽  
Sound Pressure ◽  
Porous Ceramic ◽  
Pressure Level ◽  
Test Rig ◽  
Resonance Frequencies ◽  
Lean Premixed ◽  
Ceramic Lining

This paper discusses the potential of using porous ceramic lining as insulating material in combustion chambers with respect to their sound absorbent ability to suppress thermoacoustic instabilities. For this purpose a combustion chamber test rig was developed and different types of ceramic linings were tested. The examined range of power was between 40 and 250 kW and the air-propane equivalence ratio was between 1.2 and 2.0. The overall sound pressure level and frequency domain of a lean premixed swirl stabilized and piloted burner are presented. The resonance frequencies and sound pressure levels are obtained and compared for the different combustion chamber linings. The results show a significant decrease in overall sound pressure level by up to 23.5 dB for sound absorbent lining in comparison to the common sound reflecting combustion chamber lining. In summary, sound absorbent ceramic combustion chamber lining can contribute to improve the stability of lean premixed gas turbines.

Analysis of Acoustic Signal in the MICRO Discharges Using Continuous Wavelet Transform

2006 ◽  
Vol 9 (2) ◽  
Author(s):  
Toshiyuki Nakamiya ◽  
Daiki Sasahara ◽  
Kenji Ebihara ◽  
Tomoaki Ikegami ◽  
Ryoichi Tsuda
Keyword(s):  
Wavelet Transform ◽  
Energy Distribution ◽  
Power Supply ◽  
Acoustic Signal ◽  
Continuous Wavelet Transform ◽  
Dominant Frequency ◽  
Continuous Wavelet ◽  
Electrode Current ◽  
Current Voltage ◽  
Frequency Components

AbstractTo examine the tracking phenomenon that was one of the main causes of fire breaking, fundamental experiments were carried out. To one of the electrodes AC high voltage was applied. The following samples: the mesh plate, the flat ribbon cable and the ignition plug were prepared as the electrode. Current, voltage waveforms of micro discharge and the sound signal detected by the condenser microphone were stored in the Hi-coder memory. In this paper, Continuous Wavelet Transform (CWT) was applied to determine the acoustic sound of the micro discharge and to study its dominant frequency components. Additionally, the energy distribution of acoustic signal was examined by CWT, when the frequency of power supply increased from 10 kHz to 30 kHz.

Numerical Analysis of the Acoustic Transfer Behaviour of Pressure Ducts Utilised for Microphone Measurements in Combustion Chambers

2010 ◽  
Author(s):  
Jean-Michel Lourier ◽  
Axel Widenhorn ◽  
Berthold Noll ◽  
Michael Sto¨hr ◽  
Manfred Aigner
Keyword(s):  
Temperature Distribution ◽  
Transfer Function ◽  
Combustion Chamber ◽  
Acoustic Signal ◽  
Acoustic Waves ◽  
Atmospheric Temperature ◽  
Operating Conditions ◽  
Thermal Loads ◽  
Combustion Chambers ◽  
Acoustic Transfer Function

Acoustic measurements within combustion chambers are expensive due to high thermal loads applied on the measurement devices at operating conditions. As a more feasible substitute, pressure ducts can be used to lead acoustic waves from combustion chambers to externally mounted microphones. Since these pressure ducts are purged by nitrogen at atmospheric temperature, high thermal loads are avoided. However, the acoustic signal measured within the pressure ducts is altered compared to the signal within the combustion chamber. This change in the acoustic signal can be characterised by means of the acoustic transfer function of the pressure duct, which mainly depends on the pressure ducts geometry and the combustion chambers temperature distribution. The main subject of the present paper is to analyse the influence of the combustion chambers temperature distribution on the acoustic transfer function of pressure ducts. For this scope, experiments at standard conditions and transient CFD simulations for different temperature distributions have been carried out. The acoustic signal measured in the pressure duct is found to be amplified with increasing temperatures within the combustion chamber. Moreover this amplification grows with increasing frequency of the acoustic signals.

scholarly journals A Universal Positioning System for Coupling Characterization of SEM and AFM

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jinchao Liu ◽  
Andi Wang ◽  
Ji Yang ◽  
Shiheng Yin ◽  
Xianfeng Yang
Keyword(s):  
Working Condition ◽  
Target Position ◽  
Experimental Result ◽  
Positioning System ◽  
Hyphenated Technique ◽  
Specimen Holder ◽  
Atomic Force ◽  
Comprehensive Information ◽  
Application Potential

Hyphenated techniques, providing comprehensive information in various aspects such as constituent, structure, functional group, and morphology, play an important role in scientific research. Nowadays, coupling characterization of the same position in microscale is in great need in the field of nanomaterial research and exploration. In this article, a new hyphenated technique was developed to facilitate the coupling characterization of atomic force microscope (AFM) and scanning electron microscope (SEM) by designing a universal positioning system. The system consisted of a specimen holder with coordinate grids and a software for converting the coordinate values of the same point to fit SEM, specimen holder, and AFM system. In working condition, the coordinates of the labeled points and target position were firstly extracted from the SEM operation software, then converted into the numerical values adapted to the specimen holder itself, and finally transformed into the coordinates matching the AFM system. The experimental result showed that a retrieving rate of 96% was achieved for a spherical target with a diameter of 1 μm in a 30   μ m × 30   μ m square. The hyphenated technique is a universal, accurate, efficient, and financially feasible method in microanalysis field and has great application potential.

The Matched Acoustic Generator

1972 ◽  
Vol 94 (1) ◽  
pp. 11-14
Author(s):  
K. Toda ◽  
G. Roffman ◽  
A. I. Talkin
Keyword(s):  
Measurement Error ◽  
Frequency Response ◽  
Transmission Lines ◽  
Acoustic Signal ◽  
Maximum Error ◽  
Power Gain ◽  
Frequency Range ◽  
Input Line ◽  
Pressure Signal ◽  
Frequency Responses

The design of a swept-frequency, acoustic generator for quickly measuring the insertion power gain and bandwidth of flueric components is described and illustrated. The generator is used to produce and measure the signal incident on flueric components without being affected by reflections from them. The components are connected to the generator by transmission lines. The output of the flueric component is measured in a line of the same diameter as the input line and long enough to attenuate reflections from the far end of the line to negligible levels. The generator produces a 17.7 × 10−3 kilopascal (2.6 × 10−3 psi) acoustic signal in a 1/8 in. (0.32 cm) line over the frequency range of 200 to 5000 Hz. The maximum error in the measurement of the incident pressure signal is approximately 5 percent. More precise construction of the generator could reduce the measurement error, but the accuracy is sufficient for many engineering purposes. The swept-frequency responses and carrier-pulse responses of several flueric amplifiers are illustrated and in particular the frequency response of certain proportional amplifiers has been shown to extend to 4000 Hz.

The Concentration of Air and Pulverized Coal Boiler Optimization Methods and Research

2011 ◽  
Vol 71-78 ◽  
pp. 2465-2469
Author(s):  
Xiao Hong Cheng
Keyword(s):  
Monitoring System ◽  
Working Condition ◽  
Thermal Power ◽  
Optimization Methods ◽  
Pulverized Coal Boiler ◽  
On Line ◽  
Steady Combustion ◽  
Air Speed ◽  
Secondary Air ◽  
Coal Boiler

The adjustment of the primary and secondary air speed and air quantity in thermal power plant is generally based on the measurement of static meter to show its working condition. It is difficult to adjust the air-coal parameter of each combustor to a reasonable value according to the static value for no certain relationship between the static value and the air speed is available to calculate the air speed and air quantity. The on-line monitoring system of boiler air-powder computer for real-time monitoring is adopted to keep the boiler in a state of balanced and steady combustion. The steady and accurate monitoring system and the automatic input rate of boiler (100%), which could detect the load distribution, pipe blockage, powder interruption and spontaneous combustion accurately, shows considerable value in energy conservation and great practical value in regard to combustion adjustment and reasonable distribution of air and powder.

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