Identification and characterization of coherent structures in gasoline injector nozzle flow using proper orthogonal decomposition

2016 ◽  
Vol 30 (8) ◽  
pp. 3673-3680 ◽  
Author(s):  
Muhammad Mahabat Khan ◽  
Nadeem Ahmed Sheikh
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Coherent Structures ◽  
Orthogonal Decomposition ◽  
Nozzle Flow ◽  
Injector Nozzle ◽  
Proper Orthogonal ◽  
Identification And Characterization

Analysis of Coherent Structures in the Far-Field Region of an Axisymmetric Free Jet Identified Using Particle Image Velocimetry and Proper Orthogonal Decomposition

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
A.-M. Shinneeb ◽  
R. Balachandar ◽  
J. D. Bugg
Keyword(s):  
Particle Image Velocimetry ◽  
Proper Orthogonal Decomposition ◽  
Coherent Structures ◽  
Particle Image ◽  
Axial Direction ◽  
Orthogonal Decomposition ◽  
Far Field ◽  
Field Region ◽  
Image Velocimetry ◽  
Proper Orthogonal

This paper investigates an isothermal free water jet discharging horizontally from a circular nozzle (9mm) into a stationary body of water. The jet exit velocity was 2.5m∕s and the exit Reynolds number was 22,500. The large-scale structures in the far field were investigated by performing a proper orthogonal decomposition (POD) analysis of the velocity field obtained using a particle image velocimetry system. The number of modes used for the POD reconstruction of the velocity fields was selected to recover 40% of the turbulent kinetic energy. A vortex identification algorithm was then employed to quantify the size, circulation, and direction of rotation of the exposed vortices. A statistical analysis of the distribution of number, size, and strength of the identified vortices was carried out to explore the characteristics of the coherent structures. The results clearly reveal that a substantial number of vortical structures of both rotational directions exist in the far-field region of the jet. The number of vortices decreases in the axial direction, while their size increases. The mean circulation magnitude is preserved in the axial direction. The results also indicate that the circulation magnitude is directly proportional to the square of the vortex radius and the constant of proportionality is a function of the axial location.

scholarly journals Characterization of Flow Structures Induced by Highly Rough Surface Using Particle Image Velocimetry, Proper Orthogonal Decomposition and Velocity Correlations

Engineering ◽  
2018 ◽  
Vol 10 (07) ◽  
pp. 399-416 ◽  
Author(s):  
L. R. Andersson ◽  
I. A. S. Larsson ◽  
J. G. I. Hellström ◽  
P. Andreasson ◽  
A. G. Andersson ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Proper Orthogonal Decomposition ◽  
Rough Surface ◽  
Particle Image ◽  
Orthogonal Decomposition ◽  
Flow Structures ◽  
Image Velocimetry ◽  
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.

Characterization of Flow Structures in a Diesel Injector for Different Needle Lifts and a Fluctuating Injection Pressure

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alexandre Pelletingeas ◽  
Louis Dufresne ◽  
Patrice Seers
Keyword(s):  
Steady State ◽  
Coherent Structures ◽  
Injection Pressure ◽  
Internal Flow ◽  
Orthogonal Decomposition ◽  
Navier Stokes ◽  
Flow Structures ◽  
Single Hole ◽  
Proper Orthogonal

This paper aims at analyzing the needle lift's influence on the internal flow of single-hole diesel injector to identify flow structures. A numerical Reynolds-Averaged Navier–Stokes (RANS) model of a single-hole diesel injector was developed and validated to study the flow's dynamic for different needle's lifts and subjected to realistic injection pressure. The main findings are: (1) under steady injection pressure, flow coefficients reached a steady-state value and maximum injected fuel mass flow rate is reached at intermediate needle's lifts. (2) The sac volume is the area with several vortex structures due to the throttling between the needle body and the injector body. (3) The frequency of the fluctuating injection pressure can excite the initial jet entering the sac volume similarly to the Coanda effect. Finally, using a proper orthogonal decomposition (POD) allowed extracting coherent structures within the sac volume and putting in evidence a reorganization of the flow.

Characterization of flame-shedding behavior behind a bluff-body using proper orthogonal decomposition

2012 ◽  
Vol 159 (9) ◽  
pp. 2872-2882 ◽  
Author(s):  
Stanislav Kostka ◽  
Amy C. Lynch ◽  
Bethany C. Huelskamp ◽  
Barry V. Kiel ◽  
James R. Gord ◽  
...  
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Bluff Body ◽  
Orthogonal Decomposition ◽  
Proper Orthogonal
Sign in / Sign up

Export Citation Format

Share Document