Numerical Simulation and Flame Characteristics Analysis of Non-Premixed Swirling Combustion

2021 ◽  
Author(s):  
Yi Su ◽  
Bin Zhang ◽  
Junqing Hou ◽  
Yifeng Chen ◽  
Jieyu Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
High Velocity ◽  
Temperature Fields ◽  
Pollutant Emission ◽  
Form Complex ◽  
High Temperature Area ◽  
Swirling Flames ◽  
Velocity And Temperature Fields ◽  
Temperature Area

Abstract Swirling flames are important in practical industrial combustors. The dynamic characteristics of swirling flames form complex velocity and temperature fields, which indicate combustion efficiency and influence pollutant emission. A reliable numerical simulation that can calculate the entire velocity and temperature fields is required to understand and investigate the underlying combustion mechanism. The governing equations of the methane swirling combustion process consist of the mass conservation, Navier-Stokes, and energy equations, all of which are solved by the SIMPLE algorithm based on finite volume method. This study performed a simulation using the realizable k-ε and non-premixed models in conjunction with the GRI Mech 3.0 mechanism. The characteristics of swirling combustion were analyzed on the bases of visualizations of temperature distribution, velocity distribution, and streamlines. In each cross section with varying heights from the nozzle, the high velocity and high temperature areas showed similar closed or semi-closed annular structures. In the central longitudinal section, the V-shaped high temperature and high velocity regions showed the swirling structure of the combustion flow field. The high temperature area did not coincide with the high velocity area but was located relatively downstream. The high velocity area was in the periphery of the high temperature area. Furthermore, the effects of swirl blade position on methane combustion characteristics were discussed. The validity of the numerical simulation results was verified by the simultaneous laser measurement of 3D temperature and velocity fields in the swirling flame.

Numerical Simulation of Interior Flow in Evaporation Droplet

2014 ◽  
Author(s):  
Qingming Dong ◽  
Zhentao Wang ◽  
Yonghui Zhang ◽  
Junfeng Wang
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Internal Flow ◽  
Surface Force ◽  
Droplet Surface ◽  
Force Model ◽  
Marangoni Flow ◽  
High Temperature Area ◽  
Interior Flow ◽  
Temperature Area

In this present study, the VOF (Volume of Fluid) approach is adopted to capture the interface, and CSF (Continuum Surface Force) model to calculate the surface tension, and the governing equations are founded in numerical simulation of evaporating droplets. In this work, a water droplet is assumed to be suspending in high temperature air, and the gravity of a droplet is ignored. During evaporating process of the droplet, the internal circulation flow will be induced due to the gradient of temperature at the droplet surface. The interface flows from high temperature area to low temperature area, which pulls the liquid to produce convective flow inside the droplet called as Marangoni flow. Marangoni flow makes the temperature distribution tend to uniformity, which enhances heat transfer but weakens Marangoni flow in turn. So, during droplet evaporation, the internal flow is not steady.

Direct Numerical Simulation of Heat Transfer in Converging–Diverging Wavy Channels

2006 ◽  
Vol 129 (7) ◽  
pp. 769-777 ◽  
Author(s):  
E. Stalio ◽  
M. Piller
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Temperature ◽  
Direct Numerical Simulation ◽  
Reynolds Numbers ◽  
Temperature Fields ◽  
Second Order Statistics ◽  
Iterative Procedures ◽  
Wavy Channels ◽  
Unsteady Problems

Corrugated walls are widely used as passive devices for heat and mass transfer enhancement; they are most effective when operated at transitional and turbulent Reynolds numbers. In the present study, direct numerical simulation is used to investigate the unsteady forced convection in sinusoidal, symmetric wavy channels. A novel numerical method is employed for the simulations; it is meant for fully developed flows in periodic ducts of prescribed wall temperature. The algorithm is free of iterative procedures; it accounts for the effects of streamwise diffusion and can be used for unsteady problems. Results of two simulations in the transitional regime for Reynolds numbers based on average duct height and average velocity of Re=481 and Re=872 are reported. Time averaged and instantaneous velocity and temperature fields together with second-order statistics are interpreted in order to describe the mechanism associated with heat transfer augmentation. Heat flux distributions locate the most active areas in heat transfer and reveal the effects of convective mixing. Slanted traveling waves of high temperature are identified; peak values of Nusselt number are attained when the high-temperature fluid of the waves reaches the converging walls.

Study of phase transformation temperatures of alloys based on Fe–C–Cr in high-temperature area

2018 ◽  
Vol 133 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Ľubomíra Drozdová ◽  
Bedřich Smetana ◽  
Simona Zlá ◽  
Vlastimil Novák ◽  
Monika Kawuloková ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Transformation Temperatures ◽  
High Temperature Area ◽  
Temperature Area

Numerical Simulation of the Coordination Between Velocity and Temperature Fields for Air Flow Across Staggered Elliptic Tube Bundles

2007 ◽  
Author(s):  
Yangjun Wang ◽  
Xianhe Deng ◽  
Debin Huang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Performance ◽  
Temperature Fields ◽  
Dimensionless Temperature ◽  
Dimensionless Velocity ◽  
Tube Bundles ◽  
Field Coordination ◽  
Velocity And Temperature Fields ◽  
Coordination Principle

The coordination between the velocity and temperature fields in 2-D developed turbulent flow is analyzed for air across the staggered elliptic tube bundles by means of numerical simulation. The results indicate that the convective heat transfer performance is dominated by the degree of coordination between the velocity and temperature fields. Furthermore, the included angle β between the dimensionless velocity and dimensionless temperature gradient vectors is one of the important factors to control the coordination. The field coordination can be improved by adjusting the include angle β, subsequently the heat transfer can be enhanced effectively. Field coordination principle promotes the development of heat transfer research in a controllable direction.

Numerical Simulation of Combustion Resistant Titanium Alloy Wear Behavior at High Temperature Fields

2018 ◽  
Vol 913 ◽  
pp. 168-175
Author(s):  
Xian Ye Liang ◽  
Guang Bao Mi ◽  
Liang Ju He ◽  
Pei Jie Li
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Titanium Alloy ◽  
High Temperature ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Temperature Fields ◽  
Wear Depth ◽  
Disk Model ◽  
Pin On Disk

The abnormal local friction and wear phenomena usually generate during the service of the titanium alloy rotor /stator parts of the aero engine compressor under high temperature conditions. This phenomenon is the main cause of the occurrence of titanium fire failure and has great harm. In the present investigation the friction and wear behavior of the combustion resistant titanium alloy at high temperature was studied by finite element numerical simulation and experimental verification of the pin-on-disk model. Firstly, the geometrical model of the round bottom pin-on-disk contact was established. Then, the friction process was simulated by the Coulomb friction model. The ALE technique of ABAQUS was applied to move the contact nodes and update the grid. The finite element simulation of the ARCHARD wear model was realized. In order to deal with the increasing contact area, a simplify wear direction was proposed. Finally, the wear depth and volume was calculated and the wear law at 500 °C -900 °C was revealed. The results show that the wear process is gentle at the temperature of 500-700 °C, and the wear depth is within 0.08mm when the sliding distance reaches 1800m. When the temperature exceeds 800 °C, the wear rate increased sharply and the wear depth beyond 0.1mm, the FE result is consistent with the test results.

Contour Extraction for Images of High Temperature Long Shaft Heavy Forgings

2012 ◽  
Vol 562-564 ◽  
pp. 1655-1659
Author(s):  
Qin Xiang Xia ◽  
Zhe Lin Li ◽  
Wei Qi Zong ◽  
He Qing Xie
Keyword(s):  
High Temperature ◽  
Hot Forging ◽  
Ccd Camera ◽  
Measuring Method ◽  
Contour Extraction ◽  
B Spline ◽  
High Temperature Area ◽  
The Mean ◽  
Temperature Area

Non-contact measuring method based on CCD camera is desirable for product quality of high temperature long-shaft heavy forgings. In the light of the characteristics of RGB primary color and halation in forging image, the mean red gray value in the high temperature area is proposed as the dynamic threshold to acquire external contours. Internal edges in the image of the hot forging are blurry and discontinuous. For these characteristics, a method based on quadratic B-spline curve is employed to extract and fit the internal contours. Experiments show that this method can effectively remove pseudo features and extract accurate internal and external contours for images of high temperature squaring and chamfering forgings of 900 0C to 1050 0C.

Compared Analysis of Embankment Thermal Stabilities in High Temperature Permafrost Regions with and without Climatic Warming

2012 ◽  
Vol 204-208 ◽  
pp. 1822-1829
Author(s):  
Dong Qing Li ◽  
Xing Huang ◽  
Jian Hong Fang
Keyword(s):  
Climate Change ◽  
High Temperature ◽  
Climate Warming ◽  
Eastern Tibetan Plateau ◽  
Cement Concrete ◽  
Thermal Stabilities ◽  
Stable Conditions ◽  
High Temperature Area ◽  
Permafrost Regions ◽  
Temperature Area

The heat stabilities of embankment on the high temperature permafrost regions in the eastern Tibetan Plateau without climate warming and with air temperature rising speed of 0.04°C/a were modeled, and the heights of embankment were discussed and figured out, comparatively and respectively for asphalt-paved, concrete and gravel road surface, according to the natural geographic and geologic conditions in the high temperature permafrost regions in the district. The different confined conditions about embankment critical heights with climate warming and without climate warming were discussed in the paper. Finally, the result had been obtained by numerical calculation: in the high temperature area, for the two types of laying of cement concrete and gravel surface road, the two critical heights of the thermal stable conditions were (road operation for 30 years), respectively, do not consider climate change as 2.5 m and 2.0 m, consideration of climate change were 3.5 m and 3.0 m.

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