Numerical Comparison of an Oscilla2ng Jet in a Concave Cavity. André Babineau Université de Moncton. 6 th OpenFOAM Workshop PennState University

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1 Numerical Comparison of an Oscilla2ng Jet in a Concave Cavity André Babineau Université de Moncton 6 th OpenFOAM Workshop PennState University

2 Presenta0on Plan Introduc2on Jet oscilla2on Objec2ves Configura2on OpenFOAM configura2on Findings Conclusion

3 Introduc2on Jet impingement ohen used to increase local heat transfer on a surface Most studies deal with impinging jet on a flat wall Recent studies on jet impinging concave surface, mostly on heat transfer mechanism

4 Introduc2on Concave cavity most ohen encountered in turbine blade cooling (Mar2n, 1977) Turbine engines must stay at high temperatures for op2mal efficiency Turbine blades must be ac2vely cooled Impinging jet on inside of leading edge

5 Introduc2on

6 Jet oscilla2on A jet is known to oscillate when injected into a cavity Jet can either be steady, oscillatory or transi2onal depending on the inlet posi2on (Mataoui et al., 2003) Oscilla2on frequency found to be independent of the cavity length but dependent on the width (Mataoui & Schiestel, 2009) When oscilla2on occur, there is no impingement

7 Jet oscilla2on An oscilla2ng jet evenly distributes the heat transfer on a concave surface Oscilla2on only occurs in a certain Reynolds number range for a given geometry (Hoang, 2009)

8 Jet oscilla2on A plane jet is laminar up to Reynolds number of 1400 Becomes transi2onal from a Reynolds number of 1400 to 2000 AHer a Reynolds number of 2000, the plane jet is fully turbulent (Gaunter et al., 1970)

9 Objec2ves Simulate a wide range of Reynolds number in laminar region for geometry with dimensions h/b=7 and d/b=5.2 Find oscilla2on frequency for those Reynolds numbers Detect if there is a cri2cal Reynolds number where jet starts to oscillate Compare results with the experimental data from Gilard, 2004

10 Configura2on 2D geometry

11 Configura2on Working fluid : 20 C Inlet velocity : to 2.17 m/s (uniformly distributed) Reynolds number : 100 to 1400 Rela2ve outlet pressure : 0 Pa Wall : no slip boundary condi2on Solver : Laminar

12 Configura2on 2D unstructured mesh (1 element thick) 1mm tetrahedra element Generated with GAMBIT, fluent

13 Configura2on Finite volume method OpenFOAM 1.5 to solve Navier Stokes equa2ons Transient 2D laminar flow

14 Findings Jet oscillates between two extreme posi2ons Jet deflected upward and jet deflected downward

15 Findings Velocity plohed at point A for 4 seconds

16 Findings Period extracted from peaks and frequency derived for all Reynolds number Plohed for all Reynolds number and compared with experimental

17 Findings Cri2cal Reynolds number In agreement with Gilard who found Re=440 to 540 Disagreement between numerical and experimental data

18 Conclusion Simula2on able to predict the cri2cal Reynolds number (Re=400) The numerical and experimental frequencies are not an exact match Numerical data follows the same trend of higher frequency with an increase in Reynolds number The slope of the numerical frequency vs the Reynolds number was much shallower than the experimental one

19 Conclusion Other studies will study the oscilla2on frequency into the turbulent region Will verify if the numerical frequency slope remains the same in the turbulent region Heat transfer will also be added in future studies

20 References Gaunter, J.W., Livingwood, J., Hrycak, P., 1970, Survey of literature on flow characteris2cs of single turbulent jet impinging on a flat plate, NASA Technical Note, D Gilard, V., 2004, Étude aérodynamique de jet impactant une paroi concave, PhD Thesis, Université de Poi2ers. Hoang, T.K.D., 2009, Étude du refroidissement d une paroi concave par l impact d un jet bidimensionnel, PhD Thesis, Université de Poi2ers. Mar2n, H., 1977, Heat and mass transfer between impinging gas jets and solid surfaces, Adv. In Heat Transfer, 13, pp Mataoui, A., Schiestel, R., Salem, A., 2003, Study of the oscillatory regime of a turbulent plane jet impinging in a rectangular cavity, Applied Mathema<cal Modelling, 27(2), pp Mataoui, A., Schiestel, R., 2009, Unsteady phenomena of an oscilla2ng turbulent jet flow inside a cavity: Effect of aspect ra2o, Journal of Fluids and Structures, 25, pp

Table of Contents. Foreword... xiii. Preface... xv

Table of Contents. Foreword... xiii. Preface... xv Table of Contents Foreword.... xiii Preface... xv Chapter 1. Fundamental Equations, Dimensionless Numbers... 1 1.1. Fundamental equations... 1 1.1.1. Local equations... 1 1.1.2. Integral conservation equations...