Abstract
Assessment of LES models of confined coaxial swirling jets is the aim of this paper. Despite the simple geometrical set-up of the benchmark, the flow pattern shows complex aerodynamic behavior. The case considers two coaxial jets: one axial and another annular swirling jet. The expansion when entering the chamber will produce the Outer Recirculation Zone (ORZ). If swirl number is large enough, an Inner Recirculation Zone (IRZ) is formed. The region between both recirculation zones with high shear is where mixture occurs. Post-process in space and frequency domain supplies useful information of this benchmark. Kernel cores are identified based on the lambda2 parameter. The mesh must be fine enough to capture the inertial regime of the turbulent energy spectrum. Proper Orthogonal Decomposition let identify main flow structures. To sum up, LES models provide more information than conventional RANS models and it is a step forward in any research team to gain an insight of any transitional or fully turbulent process.
Keywords
CFD LES Mixing Vortex Swirl number / CFD LES Karıştırma Vorteks Swirl sayısı
References
- T. Parra, V. Vuorinen, R. Perez, R. Szasz and F. Castro "Aerodynamic characterization of isothermal swirling flows in combustors". International Journal of Energy and Environmental Engineering 5:85. 2014.
- Roback R., Johnson B.V. Mass and momentum turbulent transport experiments with confined swirling coaxial jets, NASA CR-168252, 1983
- L. Davidson “Hybrid LES-RANS: Inlet Boundary Conditions for Flows Including Recirculation” 5th International Symposium on Turbulence and Shear Flow Phenomena TU Munich, Vol. 2, pp. 689–694, 2007
- V. Vuorinen, M. Larmi, P. Schlatter, L. Fuchs, and B.J. Boersma “A Low-Dissipative, Scale-Selective Discretization Scheme for the Navier-Stokes Equations" Computers & Fluids. 70 (2012) 195–205
- V. Vuorinen, J.-P. Keskinen, C. Duwig, O. Kaario, J. Yu, M. Larmi, and B.J. Boersma “Finite Volume Implementation of Navier-Stokes Solvers for a Variety of Flow Conditions in Open Source Environment”. Computers & Fluids. 2012
- R. E. Bensow and G. Bark “Simulating Cavitating Flows with LES in OpenFoam”. V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010
- T. Parra-Santos; R. J Pérez-Domínguez; R, Z Szasz; F. Castro. An isothermal analysis of curved-vane and flat-vane swirlers for burners. Engineering Computations. Manuscript accepted for publication on 14-07-2014
Abstract
Bu çalışmanın amacı, kapalı ortak eksenli swirl jetlerin LES modellerini değerlendirmektir. Karşılaştırmanın basit geometrik kurulumuna rağmen akış modeli kompleks aerodinamik davranış göstermektedir. Bu durumda, düz ve dairesel dönen olarak iki ortak eksenli jet göz önüne alınmıştır. Giriş odası genişlediğinde, dış resürkilasyon bölgesi (Outer Recirculation Zone (ORZ)) meydana gelir. Eğer swirl sayısı gereğinden fazla olursa iç resürkilasyon bölgesi (Inner Recirculation Zone (IRZ)) oluşur. Yüksek kesişme ile her iki resürkilasyon bölgesi arasındaki bölgede karışım meydana gelir. Boş ve frekans alanındaki ön proses bu karşılaştırmanın kullanılabilir bilgisini sağlar. İç çekirdek lambda2 parametresine bağlı olarak belirlenir. Ağ, türbülans enerji spektumunun iç rejimine dağılmak için yeri kadar iyi olmalıdır. Uygun ortogonal ayrışma ana akış yapısının belirlenmesine izin verir. Özetle, LES modeller geleneksel RANS modellerden daha çok bilgi sağlar ve herhangi bir geçiş yada tam türbülanslı sürecin adım adım anlaşılmasını sağlar.
References
- T. Parra, V. Vuorinen, R. Perez, R. Szasz and F. Castro "Aerodynamic characterization of isothermal swirling flows in combustors". International Journal of Energy and Environmental Engineering 5:85. 2014.
- Roback R., Johnson B.V. Mass and momentum turbulent transport experiments with confined swirling coaxial jets, NASA CR-168252, 1983
- L. Davidson “Hybrid LES-RANS: Inlet Boundary Conditions for Flows Including Recirculation” 5th International Symposium on Turbulence and Shear Flow Phenomena TU Munich, Vol. 2, pp. 689–694, 2007
- V. Vuorinen, M. Larmi, P. Schlatter, L. Fuchs, and B.J. Boersma “A Low-Dissipative, Scale-Selective Discretization Scheme for the Navier-Stokes Equations" Computers & Fluids. 70 (2012) 195–205
- V. Vuorinen, J.-P. Keskinen, C. Duwig, O. Kaario, J. Yu, M. Larmi, and B.J. Boersma “Finite Volume Implementation of Navier-Stokes Solvers for a Variety of Flow Conditions in Open Source Environment”. Computers & Fluids. 2012
- R. E. Bensow and G. Bark “Simulating Cavitating Flows with LES in OpenFoam”. V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010
- T. Parra-Santos; R. J Pérez-Domínguez; R, Z Szasz; F. Castro. An isothermal analysis of curved-vane and flat-vane swirlers for burners. Engineering Computations. Manuscript accepted for publication on 14-07-2014
Details
| Primary Language | English |
|---|---|
| Subjects | Engineering |
| Journal Section | Article |
| Authors | |
| Publication Date | January 12, 2015 |
| Submission Date | January 12, 2015 |
| Published in Issue | Year 2015 Volume: 4 Issue: 1 |