Budgets of Turbulent Kinetic Energy and Reynolds Normal Stresses in Coaxial Jets with and Without Swirl: A Numerical Study

Pravin Ananta Kadu; Yasuhiko Sakai; Yasumasa Ito; Koji Iwano; Masatoshi Sugino; Takahiro Katagiri; Toshiyuki Hayase; Koji Nagata

Authors

Pravin Ananta Kadu Department of Mechanical Science & Engineering, Nagoya University, Nagoya 464-8603, Japan
Yasuhiko Sakai Department of Mechanical Systems Engineering, Nagoya University, Nagoya 464-8603, Japan
Yasumasa Ito Department of Mechanical Systems Engineering, Nagoya University, Nagoya 464-8603, Japan
Koji Iwano Department of Mechanical Systems Engineering, Nagoya University, Nagoya 464-8603, Japan
Masatoshi Sugino Department of Mechanical Systems Engineering, Nagoya University, Nagoya 464-8603, Japan
Takahiro Katagiri Information Technology Center, Nagoya University, Nagoya 464-8601, Japan
Toshiyuki Hayase Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan
Koji Nagata Department of Aerospace Engineering, Nagoya University, Nagoya 464-8603, Japan

Keywords:

Jets, Swirl, turbulent kinetic energy budget, Reynolds normal stress budget, Numerical simulation

Abstract

The influence of swirl on the budgets of turbulent kinetic energy and Reynolds normal stresses is investigated for the configuration of coaxial jets by using direct numerical simulation (DNS) method. A case of strong swirl is studied and compared with a non-swirling case. As the consequence of strong swirl, a vortex breakdown bubble (VBB) is formed. Budget analysis of turbulent kinetic energy (TKE) shows that the higher energy produced at shear layers of upstream region of central stagnation point as the consequence of swirl is transported to the outer jet central region through turbulent diffusion. Moreover, TKE in outside region of VBB is convected from highly energetic upstream region to the downstream region in swirling case, whereas the positive contribution by convection term in nonswirling case seems to be smaller. Budget analysis of the Reynolds normal stresses in upstream region of central stagnation point uncovers that the pressure-strain correlation term acts as energy sink for radial component of Reynolds normal stress at outer shear layer in the swirling case contrary to non-swirling case. In swirling case, a distinctive negative production of the radial component of Reynolds normal stress is observed upstream of central stagnation point in the inner shear layer.