Time-resolved proper orthogonal decomposition of liquid jet dynamics

2009 ◽  
Vol 21 (11) ◽  
pp. 112104 ◽  
Author(s):  
Marco Arienti ◽  
Marios C. Soteriou
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Orthogonal Decomposition ◽  
Liquid Jet ◽  
Time Resolved ◽  
Proper Orthogonal

Advanced Identification of Coherent Structures in Swirl-Stabilized Combustors

2016 ◽  
Author(s):  
Moritz Sieber ◽  
Christian Oliver Paschereit ◽  
Kilian Oberleithner
Keyword(s):  
Heat Release ◽  
Proper Orthogonal Decomposition ◽  
Coherent Structures ◽  
High Speed ◽  
Low Frequency ◽  
Orthogonal Decomposition ◽  
Time Resolved ◽  
Operation Conditions ◽  
Natural Dynamics ◽  
Proper Orthogonal

We present an application of a newly introduced method to analyze the time-resolved experimental data from the flow field of a swirl-stabilized combustor. This method is based on classic proper orthogonal decomposition (POD) extended by a temporal constraint. The filter operation embedded in this method allows for continuous fading from the classic POD to the Fourier mode decomposition. This new method — called spectral proper orthogonal decomposition (SPOD) — allows for a clearer separation of the dominant mechanisms due to a clean spectral separation of phenomena. In this paper, the fundamentals of SPOD are shortly introduced. The actual focus is put on the application to a combustor flow. We analyze high-speed PIV measurements from flow fields in a combustor at different operation conditions. In these measurements, we consider externally actuated, as well as natural dynamics and reveal how the natural and actuated modes interact with each other. As shown in the paper, SPOD provides detailed insight into coherent structures in swirl flames. Two distinct PVC structures are found that are very differently affected by acoustic actuation. The coherent structures are related to heat release fluctuations, which are derived from simultaneously acquired OH* chemiluminescence measurements. Besides the actuated modes, a low frequency mode was found that significantly contribute to the global heat release fluctuations.

Study of Time-Resolved Vortex Structure of In-Cylinder Engine Flow Fields Using Proper Orthogonal Decomposition Technique

2014 ◽  
Author(s):  
Hanyang Zhuang ◽  
David L. S. Hung ◽  
Hao Chen
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Vortex Structure ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Flow Fields ◽  
Orthogonal Decomposition ◽  
Small Scale ◽  
Vortex Center ◽  
Time Resolved ◽  
Proper Orthogonal

The structure of in-cylinder flow field makes significant impacts on the processes of spray injection, air-fuel interactions, and flame development in internal combustion engines. In this study, the implementation of time-resolved Particle Image Velocimetry (PIV) in an optical engine is presented. Images at different crank angles have been taken using a high-speed double-pulsed laser and a high-speed camera with seeding particles mixed with the intake air. This study is focused on measuring the flow fields along the swirl plane at 30 mm below the injector tip under different intake air swirl ratios. A simple algorithm is presented to identify the vortex structure and to track the location and motion of vortex center at different crank angles. Proper Orthogonal Decomposition (POD) has been used to extract the ensemble and variation information of the vortex structure. Experimental results reveal that strong cycle-to-cycle variations exist in almost all test conditions. The vortex center is difficult to identify since multiple, but small scale, vortices exist during the early stage of the intake stroke. However, during the compression stroke when only one vortex center exists in most cycles, the motion of vortex center is found to be quite similar at different intake swirl ratios and engine speeds. This is due to the dominant driving force exerted by the piston’s upward motion on the in-cylinder air.

scholarly journals Liquid jet breakup unsteadiness in a coaxial air-blast atomizer

2018 ◽  
Vol 10 (3) ◽  
pp. 211-230 ◽  
Author(s):  
Abhijeet Kumar ◽  
Srikrishna Sahu
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Momentum Flux ◽  
Flux Ratio ◽  
Orthogonal Decomposition ◽  
Liquid Jet ◽  
Breakup Process ◽  
Air Blast ◽  
Breakup Length ◽  
Jet Breakup ◽  
Proper Orthogonal

The aim of this paper is to experimentally characterize the liquid jet breakup unsteadiness in a coaxial air-blast atomizer. The current research focuses on the measurement of the fluctuations of the jet breakup length and the flapping instability of the liquid jet, which contribute to the downstream fluctuations of the spray characteristics. The optical connectivity technique was used to measure the instantaneous breakup length of the water jet. Also, time resolved shadowgraph images of the primary jet breakup process were captured by high-speed imaging to characterize the jet instabilities at different axial locations from the atomizer exit. Experiments were performed for a wide range of air-to-liquid momentum flux ratio ( M) and aerodynamic Weber number ( Weg) corresponding to membrane- and/or fiber breakup mode of the jet disintegration process. The mean jet breakup length was found to vary inversely with M through a power law relation in agreement with the literature, while the breakup length fluctuations were found to first decrease and then increase with M. In order to capture the unsteady dynamics of the jet breakup process, the proper orthogonal decomposition analysis of the optical connectivity images was performed. The jet flapping and the fluctuations of the jet breakup length were identified as the second and the third spatial proper orthogonal decomposition modes, respectively, for all operating conditions of the atomizer. The amplitude and the frequency of the instabilities were measured by temporal tracking of the liquid–air interface on the shadowgraph images. The disturbance close to the injector exit corresponds to the Kelvin–Helmholtz instability, while close to the jet breakup point the jet exhibits the flapping instability, which is characterized by lateral oscillation of the jet about the atomizer axis. The influence of the liquid jet Reynolds number and momentum flux ratio on the KH and the flapping instabilities are examined.

scholarly journals Analysis of dynamics of liquid jet injected into gaseous crossflow using proper orthogonal decomposition

2020 ◽  
Author(s):  
Anirudh Asuri Mukundan ◽  
Thibaut Menard ◽  
Marcus Herrmann ◽  
Jorge Cesar Brandle de Motta ◽  
Alain Berlemont
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Orthogonal Decomposition ◽  
Liquid Jet ◽  
Analysis Of Dynamics ◽  
Proper Orthogonal
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