INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW
- 1. INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW Alexandros P. Vouros 1 , Michalis D. Mentzos 2 , Efstathios I. Xanthopoulos 1 , Andronikos E. Filios 1 and Dionissios P. Margaris 2 1 Fluid Mechanics and Turbomachinery Laboratory School of Pedagogical and Technological Education (ASPETE) N. Heraklion, Athens, Greece 2 Fluid Mechanics Laboratory and Applications Department of Mechanical Engineering and Aeronautics University of Patras, Rio, Greece 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011
- 2. Motivation and Scope 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Combining Basic Research Activities and Education promote sustainable growth of technology and science, support the strengthening of employability, creativity and innovative potentials of partners, maintain economic development of SME’s and Industry in National and Global Environment Motivate Young Researchers and Scientists attract students in fluid mechanics/dynamics in order to face current and future challenges (Clean Energy Resources, Pollution Control, Aeronautics, Biomedical Flow Problems etc.) Development of a Modern Educational Pilot Programme in Fluid Mechanics/Dynamics develop computer-based, lively and stimulating tools, demonstrate and implement the utilization of CFD and Experimental Methods of Fluid Mechanics/Dynamics in Education
- 3. Developing a “Basic Research Activities” Educational Programme 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 theoretical aspects, statistical representation of flow characteristics, state-of-the-art experimental methods (flow visualization/imaging, pressure probes, hot-wire anemometry) and computational tools (CFD) Address fundamental fluid dynamics topics in order to give a unified introduction of analytical, experimental and computational methodologies Offer illustrative examples providing a clear insight of flow properties and mechanisms while, in addition, are continuously faced in real-life applications study of boundary layers and basic shear flows including turbulent wakes and jets , production of novel results relating alternative schemes that influence ‘typical’ flows
- 4. An illustrative example : The “axisymmetric jet” problem 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 alternative geometries and influence of initial conditions nozzle geometry (contraction, smoothed or pipe), existence of confinements, wall (against free) jets, Reynolds number range, exit wall boundaries Authors Year Subject Method Hussein , Capp & George 1994 Assessment of self-similar profiles LDA, HWA Antonia & Zhao 2001 Effect of nozzle geometry HWA Kwon & Seo 2005 Effect of Reynolds number PIV Kandakure, Patkar & Patwarhan 2008 Effect of confinements CFD
- 5. RANS Simulations 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Criteria : 10 -5 continuity, 10 -4 velocity, turbulence, 10 -6 energy Reynolds number Geometry (exit wall boundary) Turbulence FLUENT’sSolver Iterations CPU Time 50000 no/yes k- ε Simplec 2682/5612 ~ 20/42min no/yes k- ε Coupled 412/1154 ~ 6/15min no/yes Reynolds Stress Coupled 982/993 ~ 14/14min 65000 no/yes k- ε Simplec 2012/5003 ~ 16/37min no/yes k- ε Coupled 305/1012 ~ 4/13min no/yes Reynolds Stress Coupled 749/626 ~ 11/9min
- 6. “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW” Velocity Contours, Grid Shaping and Details Computational model (w >50d, l >250d)
- 7. “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW” Velocity Contours, Grid Shaping and Details Computational model (w >100d, l >250d)
- 8. Streamtraces Recirculation zone behind the exit wall boundary
- 9. LabView Data Acquisition Software, connected to Pressure Transmitter Signal Experimental Rig
- 10. Axial Decay of Mean Axial Velocity Several Turbulence Models and FLUENT ‘s Solvers vs Experimental Data 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Vouros, A.P., Mentzos, M.D., Xanthopoulos, E.I., Filios A.E. and Margaris, D.P. “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW”
- 11. Mean and Turbulent Velocity Profiles Influence of the exit wall using Reynolds-Stress Turbulence Model 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Alexandros P. Vouros 1 , Michalis D. Mentzos 2 , Eftsathios I. Xanthopoulos 1 , Andronikos E. Filios 1 and Dionissios P. Margaris 2 “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW”
- 12. Non Dimensional Profiles Profiles of the non-dimensional mean axial velocity using local velocity and length scales. Self-Similarity Concept 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Alexandros P. Vouros 1 , Michalis D. Mentzos 2 , Eftsathios I. Xanthopoulos 1 , Andronikos E. Filios 1 and Dionissios P. Margaris 2 “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW”
- 13. Non Dimensional Profiles Profiles of the non-dimensional turbulent shear stress using local velocity and length scales. Self-Similarity Concept 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Alexandros P. Vouros 1 , Michalis D. Mentzos 2 , Eftsathios I. Xanthopoulos 1 , Andronikos E. Filios 1 and Dionissios P. Margaris 2 “ INFLUENCE OF A CIRCULAR EXIT WALL BOUNDARY ON THE AXISYMMETRIC JET FLOW”
- 14. Concluding Remarks 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 In the frame of an ongoing ‘basic research activities’ project implemented in the educational programme of FMTULAB ‘s courses in ASPETE, an experimental and computational study address the influence of different inflow conditions on the typical ‘free’ turbulent axisymmetric jet. The study focuses on the effect of a wall boundary produced by a circular disk of twice the jet diameter placed on the exit of the jet. Velocity distributions are analyzed and compared to those of the typical free jet, based on simulations utilizing different Fluent’s ® solvers, while supportive pressure measurements are used for the evaluation of turbulence models. When the exit wall boundary is used, the mean streamwise centerline velocity decays slightly faster, while the radial profiles of the mean and turbulent velocity moments indicate that at the same distance from orifice, the free-jet forms a stronger mixing layer with the surroundings. In contrast, for the non dimensional profiles the trends are reversed, since the profiles for jet with the exit wall boundary lie on systematically higher values, indicating that for similar centerline streamwise velocities, it is this type of jet that interacts excessively with the ambient air.
- 15. THANK YOU FOR YOUR ATTENTION! QUESTIONS? 7th GRACM International Congress on Computational Mechanics Athens, 30 June – 2 July 2011 Lab : http://fmtulab.meed-aspete.net/ Support the Fmtulab Project: http://fmtulab.wikidot.com/