Examination of Oscillating Frequencies Generated by Combustion Oscillation Considering Temperature Distribution in a Combustor Tube Fueled by Natural Gas and Hydrogen Mixture

2020 ◽  
Author(s):  
Akane Uemichi ◽  
Kan Mitani ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Temperature Distribution ◽  
Natural Gas ◽  
Transfer Matrix ◽  
Fuel Mixture ◽  
One Dimensional ◽  
Temperature Distributions ◽  
Combustion Oscillation ◽  
The Town ◽  
Small Elements ◽  
Oscillation Experiment

Abstract A combustion oscillation experiment fueling a mixture of hydrogen and natural gas was performed. The results showed oscillating frequencies of around 350 Hz in the case of the town gas only, whereas oscillating frequencies of around 200 and 400 Hz were observed in the hydrogen-containing fuel case. We hypothesized that the oscillating frequencies shift may occur by changing the temperature-distribution inside the tube, which was caused by different combustion conditions with the fuel mixture. As a result, the possible oscillating frequencies of not only around 350 Hz but also around 200 and 400 Hz were obtained. Although three types of possible oscillating frequencies were obtained in our previous study, more detailed temperature distributions should be considered to clarify the effect of the changing fuel mixture composition. In this paper, representative one-dimensional temperature distributions were formed by the combination of measured and calculated temperature distributions in the combustion tube for the corresponding fuel mixture. To include the detailed temperature distributions, the acoustic network model was divided into enough small elements to express the temperature distributions, where each element was connected by the transfer matrix. Then, the possible oscillating frequencies were calculated, taking account of the influence of the temperature distributions.

Transient Heat Transfer Analysis of Alloy Solidification

1973 ◽  
Vol 95 (3) ◽  
pp. 324-331 ◽  
Author(s):  
J. C. Muehlbauer ◽  
J. D. Hatcher ◽  
D. W. Lyons ◽  
J. E. Sunderland
Keyword(s):  
Temperature Distribution ◽  
Eutectic Composition ◽  
Approximate Solutions ◽  
The Other ◽  
Heat Transfer Analysis ◽  
Uniform Temperature ◽  
One Dimensional ◽  
Temperature Distributions ◽  
Finite Slab ◽  
Good Agreement

Approximate solutions are obtained for the temperature distribution and rate of phase change for the transient one-dimensional solidification of a finite slab of a binary alloy. The alloy is selected to avoid the eutectic composition so that solidification takes place over a range of temperatures. The slab is initially superheated and has a uniform temperature distribution. Solidification occurs after one surface is cooled by convection while the other surface is insulated. Temperature distributions are determined analytically and experimentally and are in reasonably good agreement.

Combustion Oscillation in Gas Turbine Combustor for Fuel Mixture of Hydrogen and Natural Gas

2017 ◽  
Author(s):  
Akane Uemichi ◽  
Ippei Kanetsuki ◽  
Shigehiko Kaneko
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pressure Fluctuation ◽  
Acoustic Impedance ◽  
Fuel Mixture ◽  
Combustion Characteristics ◽  
Impedance Method ◽  
Gas Turbine Combustor ◽  
Interaction Index ◽  
Combustion Oscillation

Hydrogen as one of energy sources is attracting attentions because of CO2 free combustion that can deaccelerate global warming. Recently, hydrogen enriched combustion technology for gas turbine combustors is developing, in which hydrogen is added to natural gas. However, hydrogen-rich combustion has different combustion characteristics from conventional natural gas combustion. In particular, such variety of combustion characteristics may lead to combustion oscillation, which may cause fatigue breaking of structural elements due to resonance with components. Combustion oscillation is mainly induced by thermo-acoustics interaction. Therefore, it is necessary to investigate characteristics of hydrogen-enriched combustion sufficiently. To understand combustion characteristics of enriched hydrogen mixture, combustion experiments were performed for various ratios of hydrogen in the fuel mixture. In this study, a mock-up combustor of a micro gas turbine combustor is used, where a radial swirler is installed to mix fuel and air and stabilize the flame. To grasp the characteristics of combustion oscillation, pressure fluctuation was detected by a pressure sensor installed at the bottom of the combustor. It is found that larger hydrogen ratio in the fuel mixture extends the range of large pressure fluctuation region expressed by the root-mean-square value. Succeedingly, more detail oscillation characteristics were examined by FFT analysis. In the case of natural gas 100%, the oscillation of around 350 Hz was detected. On the other hand, in the case of the hydrogen-contained fuel mixture, two kinds of oscillating frequencies around 200 and 400 Hz were detected. To examine the cause of the difference among these three oscillating frequencies, a simplified stepped tube model with closed- and open-end is considered. For further investigation, acoustic boundary conditions were measured by acoustic impedance method. Moreover, to obtain the representative flame positions and temperature in the combustor, CFD calculations were performed, and the measured acoustic impedance was combined with the CFD results. Then, parametric studies with various thermo-pressure interaction index were performed to obtain the effect of thermo-pressure interaction index on natural frequencies and gains using the Nyquist plot. As a result, it was found that the self-excited oscillation limit is sensitive to the value of thermo-pressure interaction index.

Oscillating Frequencies Generated by Combustion Oscillation in a Combustor Tube Fueled by Natural Gas and a Hydrogen Mixture

2021 ◽  
Author(s):  
Akane Uemichi ◽  
Kan Mitani ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Growth Rate ◽  
Temperature Distribution ◽  
Natural Gas ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Nyquist Plot ◽  
Linear Temperature ◽  
Linear Temperature Gradient ◽  
The Difference ◽  
Combustion Oscillation

Abstract From previous combustion oscillation experiments using a simulated gas turbine combustor, oscillation frequencies around 350 Hz were measured in only natural gas-fired, and around 200 and 400 Hz were measured in the case of hydrogen-containing fuel. In this study, the axial gas column vibration mode was assumed, and the method to reproduce the change of oscillating frequency due to the difference of fuel was investigated. In the previous study, the temperature distribution in the combustor was divided into only two regions, and there were problems in terms of parameter estimation for modeling the flame dynamics. Therefore, the transfer matric method that incorporates a linear temperature gradient was employ. Also, the temperature distributions obtained from CFD and experiments were reduced to one dimension to reproduce the difference in combustion characteristics due to the difference in fuel composition; four methods were proposed, the axial representative temperatures. The Nyquist plot method was used to calculate up to 10 combinations of resonant frequency and growth rate simultaneously. And the oscillation frequency was determined in which the resonance frequency with the maximum growth rate was. As a result, the value of the oscillating frequency obtained was different depending on the method of creating the representative temperature distribution.

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

scholarly journals Selective spin transport through a quantum heterostructure: Transfer matrix method

2016 ◽  
Vol 30 (25) ◽  
pp. 1650184 ◽  
Author(s):  
Moumita Dey ◽  
Santanu K. Maiti
Keyword(s):  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Spin Transport ◽  
Tight Binding ◽  
Transmission Probability ◽  
Applied Bias Voltage ◽  
One Dimensional ◽  
Wide Range ◽  
Nanoscale Level

In the present work, we propose that a one-dimensional quantum heterostructure composed of magnetic and non-magnetic (NM) atomic sites can be utilized as a spin filter for a wide range of applied bias voltage. A simple tight-binding framework is given to describe the conducting junction where the heterostructure is coupled to two semi-infinite one-dimensional NM electrodes. Based on transfer matrix method, all the calculations are performed numerically which describe two-terminal spin-dependent transmission probability along with junction current through the wire. Our detailed analysis may provide fundamental aspects of selective spin transport phenomena in one-dimensional heterostructures at nanoscale level.

Ultra-Low Emission Hydrogen/Syngas Combustion With a 1.3 MW Injector Using a Micro-Mixing Lean-Premix System

2011 ◽  
Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Flame Temperature ◽  
Fuel Mixture ◽  
Full Scale ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Nitrogen Dilution ◽  
Fuel Mixtures

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.

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