scholarly journals PECULIARITIES OF FLOW AND MIXTURE FORMATION IN MICROIET BURNER DEVICES WITH ASYMMETRIC FUEL DISTRIBUTION

2019 ◽  
Vol 41 (1) ◽  
pp. 11-19
Author(s):  
N.М. Fialko ◽  
Ju.V. Sherenkovskyi ◽  
N.O. Meranova ◽  
S.A. Alioshko ◽  
K.V. Rokytko
Keyword(s):  
Flow Characteristics ◽  
Reverse Current ◽  
Combustion Stability ◽  
Cfd Modeling ◽  
Mixture Formation ◽  
Fuel Gas ◽  
Fuel Distribution ◽  
Excess Air ◽  
The Mean ◽  
Current Zone

The purpose of the work is to establish the regularities of the isothermal flow and the mixture formation of the fuel gas and oxidant in the microjet burner devices with an asymmetric fuel supply. The main tasks of the work are the analysis of the effects of the influence of the value of excess air factor on the flow structure and the features of the mixing of fuel and oxidant. As a method of research, the CFD modeling method using the FLUENT code was used. According to the results of the studies carried out in the relatively wide limits of the change in the excess air factor (1.5 ≤ α ≤ 4.0), the regularities of the effect of the value of this factor on such flow characteristics in the burners studied as the length of the reverse current zone behind the flame stabilizer, which is responsible for the combustion stability, the location of main vortex in this zone, the values of the mean-square velocity pulsations, and so on. The features of the mixture formation in the variation of the α value in the burner devices under investigation are revealed. The dependence on the mean α of the methane concentration in the reciprocal zone is established and given its interpretation, taking into account a number of competing factors.

scholarly journals THE INFLUENCE OF THE COMPOSITION AND PARAMETERS OF THE OIL GAS SUPPLY ON THE COMBUSTION LIMITS IN THE COMBUSTION CHAMBER

2020 ◽  
pp. 64-71
Author(s):  
Alyona Shilova ◽  
◽  
Roman Bulbovich ◽  
Nikolay Bachev ◽  
Oleg Matyunin ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Power Plants ◽  
Central Place ◽  
Combustion Stability ◽  
Fuel Gas ◽  
Micro Gas Turbine ◽  
Gas Utilization ◽  
Excess Air ◽  
Combustion Limits ◽  
Oil Gas

The question of oil gas utilization today is very important.In the development of domestic micro-gas-turbine utilization power plants, the central place is occupied by the creation of a universal combustion chamber, which would ensure stable combustion of ballasted gases at different fields under variable operating conditions.In this work, the phlegmatization method was used to determine the lower and upper concentration limits, which allows taking into account the effect of ballasting components on the combustion limits. When calculating the coefficients of excess air at the upper and lower limits, the influence of the composition, temperature, and supply pressure of the components was taken into account.An analysis of the results showed that taking into account the parameters of air and oil gas at the outlet of the compressors expands the limits of combustion by the coefficient of excess air. An additional regenerative heating of the air between the compressor and the combustion chamber shifts the combustion stability region in terms of the excess air coefficient towards rich mixtures. Recuperative heating of fuel gas shifts the area of sustainable combustion towards lean mixtures. Simultaneous regenerative heating of fuel gas and air expands the area of sustainable combustion.

scholarly journals Experimental study on the mean flow characteristics of a supersonic multiple jet configuration

2021 ◽  
Vol 108 ◽  
pp. 106377
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Characteristics ◽  
Mean Flow ◽  
The Mean

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

scholarly journals Improving Blowout Performance of the Conical Swirler Combustor by Employing Two Parts of Fuel at Low Operating Condition

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1681
Author(s):  
Yixiang Yuan ◽  
Qinghua Zeng ◽  
Jun Yao ◽  
Yongjun Zhang ◽  
Mengmeng Zhao ◽  
...  
Keyword(s):  
Distribution Ratio ◽  
Performance Enhancement ◽  
Experimental Testing ◽  
Stability Boundary ◽  
Operating Conditions ◽  
Nox Emission ◽  
Combustion Stability ◽  
Gas Temperature ◽  
Contact Ratio ◽  
Fuel Distribution

Aiming at the problem of the narrow combustion stability boundary, a conical swirler was designed and constructed based on the concept of fuel distribution. The blowout performance was studied at specified low operating conditions by a combination of experimental testing and numerical simulations. Research results indicate that the technique of the fuel distribution can enhance the combustion stability and widen the boundary of flameout within the range of testing conditions. The increase of the fuel distribution ratio improves the combustion stability but leads to an increase in NOx emission simultaneously. The simulation results show the increase of the fuel distribution ratio causes contact ratio increase in the area of lower reference velocity and gas temperature increase. The increased contact ratio and temperature contribute to the blowout performance enhancement, which is identical to the analysis result of the Damkohler number. The reported work in this paper has potential application value for the development of an industrial burner and combustor with high stability and low NOx emission, especially when the combustion system is required to be stable and efficient at low working conditions.

Integrated analysis of the excess air on steam power plant CFB boiler using mathematical and CFD modeling

2018 ◽  
Author(s):  
Hariyotejo Pujowidodo ◽  
Ahmad Indra Siswantara ◽  
Budiarso ◽  
Asyari Daryus ◽  
Gun Gun Ramdlan Gunadi
Keyword(s):  
Power Plant ◽  
Cfd Modeling ◽  
Integrated Analysis ◽  
Steam Power ◽  
Cfb Boiler ◽  
Steam Power Plant ◽  
Excess Air

Role of Plaque Morphology in Altering the Flow Characteristics in Diseased Coronary Artery

2012 ◽  
Author(s):  
Carlos Moreno ◽  
Kiran Bhaganagar
Keyword(s):  
Coronary Artery ◽  
Nonlinear Response ◽  
Flow Characteristics ◽  
Proximal Region ◽  
Patient Specific ◽  
Plaque Morphology ◽  
Mean Velocity ◽  
Peak Location ◽  
The Mean

Patient specific simulations of a single patient based on an accurate representation of the plaque in a diseased coronary artery with 35% stenosis are performed to understand the effect of inlet forcing frequency and amplitude on the wall shear stress (WSS). Numerical simulations are performed with unsteady flow conditions in a laminar regime. The results have revealed that at low amplitudes, WSS is insensitive to forcing frequency and is it in phase with Q. The maximum WSS is observed at the proximal region of the stenosis, and WSS has highest negative values at the peak location of the stenosis. For higher pulsatile amplitude (a > 1.0), WSS exhibits a strong sensitivity with forcing frequencies. At higher forcing frequency the WSS exhibits nonlinear response to the inlet forcing frequency. Furthermore, significant differences in the mean velocity profile are observed during maximum and minimum volumetric flow rates.

The effects of flue-wall design modifications on combustion and flow characteristics of an aluminum anode baking furnace-CFD modeling

2018 ◽  
Vol 230 ◽  
pp. 207-219 ◽  
Author(s):  
Abdul Raouf Tajik ◽  
Tariq Shamim ◽  
Mouna Zaidani ◽  
Rashid K. Abu Al-Rub
Keyword(s):  
Flow Characteristics ◽  
Cfd Modeling ◽  
Aluminum Anode

scholarly journals Investigation of Flow through a Labyrinth Seal

2021 ◽  
Vol 13 (2) ◽  
pp. 51-58
Author(s):  
Marius ENACHE ◽  
Razvan CARLANESCU ◽  
Andreea MANGRA ◽  
Florin FLOREAN ◽  
Radu KUNCSER
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Labyrinth Seal ◽  
Cfd Modeling ◽  
Gas Temperature ◽  
Continuous Increase ◽  
Seal Design ◽  
Air Temperatures ◽  
Flow Through ◽  
Gas Leaks

Growing performance requirements for gas turbines have led to a continuous increase in gas temperature and pressure ratios. Together with the resulting increase in cooling flows, this requires more and more minimization and control of internal gas leaks. To meet future performance goals, the application of a new seal design and an improved understanding of leakage flow characteristics are of particular importance. The air mass flow through a labyrinth seal designed for a low-pressure turbine has been determined both through analytical calculus and CFD modeling. Different radial clearances and different air temperatures have been considered. In the next stage, the results will be validated through experiments.

Establishment of the Wake Behind a Disk

1964 ◽  
Vol 86 (4) ◽  
pp. 869-880 ◽  
Author(s):  
Thomas Carmody
Keyword(s):  
Shear Stress ◽  
Ambient Pressure ◽  
Continuous Distribution ◽  
Flow Characteristics ◽  
Graphical Form ◽  
Stress Distributions ◽  
Mean Velocity ◽  
Pressure Distributions ◽  
Energy Relationships ◽  
The Mean

An air-tunnel study of the establishment of the wake behind a disk at a Reynolds number of approximately 7 × 104 was undertaken. On the basis of the measured data, such a wake is fully established, that is, similarity profiles of the flow characteristics are formed, within 15 diameters of the disk, and approximately 95 percent of the transfer of energy from the mean motion to the turbulence motion takes place within 3 diameters of the disk, in the region of the mean standing eddy. The measured mean ambient-pressure and mean total-pressure distributions, mean velocity distributions, turbulence-intensity and shear-stress distributions, and the mean streamline pattern are presented in graphical form, as are the quantitative balances of the integrated momentum and mean-energy relationships. A stream function consisting of a continuous distribution of doublets is introduced to extend the radial limit of understanding of the flow characteristics to a very large if not infinite radius. Considerable attention is given to the problem of obtaining and interpreting turbulence shear-stress data immediately downstream from the point of flow separation. The applicability of a local diffusion coefficient or virtual viscosity of the Boussinesq or Prandtl type for relating the turbulence shear stress to the radial gradient of mean axial velocity is discussed. The Bernoulli sum and the energy changes along individual streamlines investigated in an associated study are incorporated herein to obtain a quantitative estimate of the local errors involved in the turbulence-shear-stress measurements.

FULL SCALE EXPERIMENT AND NUMERICAL ANALYSIS FOR THE PERFORMANCE OF HEAT EXCHANGER IN MOLTEN CARBONATE FUEL CELLS

2016 ◽  
Vol 40 (5) ◽  
pp. 799-810
Author(s):  
Seon-Hwa Kim ◽  
Byeong-Keun Choi ◽  
Young-Su An
Keyword(s):  
Heat Exchanger ◽  
Fuel Cell ◽  
Flow Characteristics ◽  
Cell System ◽  
Molten Carbonate Fuel Cell ◽  
Molten Carbonate ◽  
Fuel Gas ◽  
Operation Conditions ◽  
Scale Down ◽  
Scale Experiment

This study presents a numerical simulation of heat transfer and flow characteristics of the heat exchanger in molten carbonate fuel cell system. In this study, the actual size of the heat exchanger was simulated in order to avoid errors that can occur from the scale-down test, also the simulation gas (air) was verified with the heat duty of 800,000 kcal/hr. It is analyzed by using a commercial heat exchanger calculation code based upon the test condition. It is found that a reasonable agreement is obtained from comparison between the predicted results and the measured data. Furthermore, the verified similarity was presented in this analysis. In particular, the simulation gas used for the shell side service for the heat exchanger is obtained through the combustion calculation, i.e. by using a flow rate of the fuel gas. In addition, the performance of the heat exchanger is predicted under various conditions in the fuel cell operation conditions by the numerical model.

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