scholarly journals Numerical Study of Flame Propagation Morphology for Deflagration in the Pipeline Using Proper Orthogonal Decomposition

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Weimin Wu ◽  
Jianyao Yao ◽  
Jingcheng Liu ◽  
Zejun Wu ◽  
Jiawen Liu
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Information Content ◽  
Flame Propagation ◽  
Numerical Study ◽  
Propagation Speed ◽  
Orthogonal Decomposition ◽  
Order Mode ◽  
Propagation Characteristics ◽  
Calculation Results ◽  
Proper Orthogonal

A multilevel independent spatial modal analysis of flame propagation characteristics of a deflagration in a specific pipeline was performed using the proper orthogonal decomposition (POD) method, in order to research the evolution process of the explosion which is closely related to flame propagation speed and front rupture pressure. The CFD results indicated that the full-order calculation results well agreed with the normal combustion propagation characteristics of premixed methane-air for the flame propagation with the unbroken thin layer. The POD analysis results showed that the static temperature gradient of the 1st order mode of initial and subsequent stages both exhibited a range of continuity change from left to right, and the frontal curvature of the cooling area decreased as the flame propagated in all stages. The number of the low-temperature interval regions displayed an expanding form of a staircase with the increase of the mode order, especially for subsequent flame in which the interval areas became more and more slender. Moreover, the level of information content in the multilevel modal space was mostly concentrated in the first 3 modes, especially in the 1st order mode, and the flame propagation pattern at the initial stage was more complicated than the subsequent based on the relational information content features.

Investigation of Cycle-to-Cycle Variation of In-Cylinder Engine Swirl Flow Fields Using Quadruple Proper Orthogonal Decomposition

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Penghui Ge ◽  
David L. S. Hung
Keyword(s):  
Proper Orthogonal Decomposition ◽  
High Speed ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Propagation Speed ◽  
Fuel Mixture ◽  
Flow Fields ◽  
Swirl Flow ◽  
Orthogonal Decomposition ◽  
Proper Orthogonal

It has been observed that the swirl characteristics of in-cylinder air flow in a spark ignition direct injection (SIDI) engine affect the fuel spray dispersion and flame propagation speed, impacting the fuel mixture formation and combustion process under high swirl conditions. In addition, the cycle-to-cycle variations (CCVs) of swirl flow often degrade the air–fuel mixing and combustion quality in the cylinder. In this study, the 2D flow structure along a swirl plane at 30 mm below the injector tip was recorded using high-speed particle image velocimetry (PIV) in a four-valve optical SIDI engine under high swirl condition. Quadruple proper orthogonal decomposition (POD) was used to investigate the cycle-to-cycle variations of 200 consecutive cycles. The flow fields were analyzed by dividing the swirl plane into four zones along the measured swirl plane according to the positions of intake and exhaust valves in the cylinder head. Experimental results revealed that the coefficient of variation (COV) of the quadruple POD mode coefficients could be used to estimate the cycle-to-cycle variations at a specific crank angle. The dominant structure was represented by the first POD mode in which its kinetic energy could be correlated with the motions of the intake valves. Moreover, higher order flow variations were closely related to the flow stability at different zones. In summary, quadruple POD provides another meaningful way to understand the intake swirl impact on the cycle-to-cycle variations of the in-cylinder flow characteristics in SIDI engine.

Investigation of Cycle-to-Cycle Variation of In-Cylinder Engine Swirl Flow Fields Using Quadruple Proper Orthogonal Decomposition

2016 ◽  
Author(s):  
Penghui Ge ◽  
David L. S. Hung
Keyword(s):  
Proper Orthogonal Decomposition ◽  
High Speed ◽  
Combustion Process ◽  
Propagation Speed ◽  
Fuel Mixture ◽  
Flow Fields ◽  
Swirl Flow ◽  
Orthogonal Decomposition ◽  
Fuel Spray ◽  
Proper Orthogonal

It has been observed that the swirl characteristics of in-cylinder air flow in a spark ignition direct-injection (SIDI) affect the fuel spray dispersion and flame propagation speed, impacting the fuel mixture formation and combustion process under higher conditions. In addition, the cycle-to-cycle variations of swirl flow often degrade the fuel spray mixing and combustion quality in the cylinder. In this study, the 2D flow structure along a swirl plane at 30 mm below the injector tip was recorded using high-speed particle image velocimetry in a four-valve optical SIDI engine under high swirl condition. Quadruple proper orthogonal decomposition (POD) was used to investigate the cycle-to-cycle variations of 200 consecutive cycles during the intake and compression strokes. The flow fields were analyzed by dividing the swirl plane into four zones along the measured swirl plane according to the positions of intake and exhaust valves in the cylinder head. Experimental results revealed that the coefficient of variation (COV) of the time coefficients of the quadruple POD mode coefficients could be used to estimate the cycle-to-cycle variations at a specific crank angle. The dominant structure was represented by the first POD mode in which its kinetic energy could be correlated with the motions of the intake valve. Moreover, the higher order flow variations were closely related to the flow stability at different zones. In summary, quadruple POD provides another meaningful way to understand the intake swirl impact on the cycle-to-cycle variations of the in-cylinder flow characteristics in SIDI engine.

scholarly journals Simulating Bluff-Body Flameholders: On the Use of Proper Orthogonal Decomposition for Combustion Dynamics Validation

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Ryan Blanchard ◽  
A. J. Wickersham ◽  
Lin Ma ◽  
Wing Ng ◽  
Uri Vandsburger
Keyword(s):  
Heat Release ◽  
Proper Orthogonal Decomposition ◽  
High Speed ◽  
Bluff Body ◽  
Numerical Study ◽  
Orthogonal Decomposition ◽  
Time Averaging ◽  
Reacting Flow ◽  
Combustion Dynamics ◽  
Proper Orthogonal

Contemporary tools for experimentation and computational modeling of unsteady and reacting flow open new opportunities for engineering insight into dynamic phenomena. In this article, we describe a novel use of proper orthogonal decomposition (POD) for validation of the unsteady heat release of a turbulent premixed flame stabilized by a vee-gutter bluff-body. Large-eddy simulations were conducted for the same geometry and flow conditions as examined in an experimental rig with chemiluminescence measurements obtained with a high-speed camera. In addition to comparing the experiment to the simulation using traditional time-averaging and pointwise statistical techniques, the dynamic modes of each are isolated using proper orthogonal decomposition (POD) and then compared mode-by-mode against each other. The results show good overall agreement between the shapes and magnitudes of the first modes of the measured and simulated data. A numerical study of into the effects of various simulation parameters on these heat release modes showed significant effects on the flame's effective angle but also on the size, shape, and symmetry patterns of the flame's dynamic modes.

Prediction of Ice Shape for Three-Dimensional Engine Inlet Based on the Proper Orthogonal Decomposition Method

2014 ◽  
Vol 1008-1009 ◽  
pp. 1011-1015
Author(s):  
Xiao Bin Shen ◽  
Zuo Dong Mu ◽  
Gui Ping Lin ◽  
Yue Zhou
Keyword(s):  
Numerical Calculation ◽  
Proper Orthogonal Decomposition ◽  
Decomposition Method ◽  
Three Dimensional ◽  
Orthogonal Decomposition ◽  
Ice Accretion ◽  
3D Engine ◽  
Calculation Results ◽  
Ice Shapes ◽  
Proper Orthogonal

To increase the prediction speed of ice accretion on the 3D engine inlet, the Proper Orthogonal Decomposition (POD) method was introduced. Taking the ice shapes from CFD numerical calculation results as samples, in view of the change of icing temperature, the procedures of predicting the ice shapes by POD method were introduced, which used ice shapes’ coordinates and ice accretion height as compute parameters, respectively. The POD and CFD ice shapes were found coincident, which indicates that the POD method can fast and accurately calculate the 3D engine inlet ice shapes. The results from the two different POD parameters were shown and compared, and the ice shapes were nearly the same, which means they have the same effect. However, the POD method based on ice accretion height is simpler and more appropriate

A Numerical Study on the Effects of Acoustic Forcing on Fuel Spray Dynamics in Gas Turbines

2020 ◽  
Author(s):  
Nicholas C. W. Treleaven ◽  
Andrew Garmory ◽  
Gary J. Page
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Gas Turbines ◽  
Numerical Study ◽  
Mixture Fraction ◽  
Orthogonal Decomposition ◽  
Computational Domain ◽  
Fuel Injector ◽  
Design Modification ◽  
Acoustic Forcing ◽  
Proper Orthogonal

Abstract In the case of aircraft engines, the fuel is injected as a liquid spray which may play a role in thermoacoustic instabilities through creating changes to the mixture fraction inside the combustion chamber. This study uses two-phase incompressible non-reacting large eddy simulation with Lagrangian particle tracking to show how spray droplets of different sizes can be affected by large scale hydrodynamic structures and acoustic forcing. The forcing is applied at the inlets of a truncated computational domain that only includes the geometry downstream of the fuel injector using the newly developed PODFS (proper orthogonal decomposition Fourier series) method. The PODFS is a model that can reproduce the effects of acoustic forcing by extracting planes of data from an auxiliary acoustically forced compressible unsteady Reynolds averaged Navier-Stokes simulation. A proper orthogonal decomposition analysis shows that fuel droplets of a typical size seen in jet engines are more sensitive to acoustic and hydrodynamic structures than droplets with an order of magnitude larger or smaller diameter, consistent with their Stokes number. Phase and azimuthally averaged results show that fluctuations of the spray mixture fraction represented by large droplets affect the total spray mixture fraction much more than fluctuations of the small droplets. An additional intermittent spray dispersion mechanism was identified that is due to intermittent vorticity being generated between the two outer injector flow passages. An injector design modification has been suggested that will reduce the prevalence of this mechanism.

Sign in / Sign up

Export Citation Format

Share Document