Conference on Turbulence and Interactions TI2006 May June Porquerolles France

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Niveau: Supérieur, Doctorat, Bac+8
Conference on Turbulence and Interactions TI2006, May 29 - June 2, 2006, Porquerolles, France DNS of a Turbulent Channel Flow with Streamwise Rotation at Different Reynolds Numbers T. Weller?, M. Oberlack? ?Fluid Dynamics Group, Technische Universitat Darmstadt, Petersenstraße 13, D-64287 Darmstadt, Germany ABSTRACT In this work a turbulent channel flow rotating about the streamwise direction is presented. The theory is based on the investigations of [3] employing the symmetry group theory. It was found that a cross flow in the spanwise direction is induced. Statistical evaluations have shown that all six components of the Reynolds stress tensor are non-zero. A series of direct numerical simulations (DNS) has been conducted at rotation number Ro=20 for different Reynolds numbers. In this paper the results of the DNS are presented and discussed. INTRODUCTION Rotating turbulent flows play more a major role in engineering applications such as in gas turbine blade passages, pumps and rotating heat exchang- ers to name only a few. In these cases secondary flows are induced caused by centrifugal or Cori- olis forces. Investigations of [3] using symme- try theory showed that there is a new turbulent scaling law related to the turbulent channel flow rotating about the mean flow direction. Figure 1 depicts the flow geometry. x1 x2 x3 ?1 u1 u3 Fig.

• ferent reynolds


• reynolds numbers


• channel flow


• streamwise mean


• show also


• turbulent channel


• all computation


• both streamwise


• finalized all

Sujets

• Stanford University

Informations

• Publié par: profil-zyak-2012
• Nombre de lectures: 9
• Langue: English

Extrait

Conference on Turbulence and Interactions TI2006, May 29  June 2, 2006, Porquerolles, France

DNS of a Turbulent Channel Flow with Streamwise Rotation at Different Reynolds Numbers

∗ ∗ T. Weller , M. Oberlack ∗ Fluid Dynamics Group, Technische Universität Darmstadt, Petersenstraße 13, D64287 Darmstadt, Germany

ABSTRACT In this work a turbulent channel flow rotating about the streamwise direction is presented. The theory is based on the investigations of [3] employing the symmetry group theory. It was found that a cross flow in the spanwise direction is induced. Statistical evaluations have shown that all six components of the Reynolds stress tensor are nonzero. A series of direct numerical simulations (DNS) has been conducted at rotation number Ro=20 for different Reynolds numbers. In this paper the results of the DNS are presented and discussed.

I NTRODUCTION

Rotating turbulent flows play more a major role in engineering applications such as in gas turbine blade passages, pumps and rotating heat exchang ers to name only a few. In these cases secondary flows are induced caused by centrifugal or Cori olis forces. Investigations of [3] using symme try theory showed that there is a new turbulent scaling law related to the turbulent channel flow rotating about the mean flow direction. Figure 1 depicts the flow geometry.

W 1

x 3

x 2

u 1

u 3

x 1

Fig. 1. Sketch of the flow geometry of a turbulent channel flow rotating about the mean flow direction

The flow has several common features with the classical rotating channel flow rotating about the spanwise direction [1] but also has some different characteristics. The induction of a mean velocity inx 3 direction [4] is the most obvious difference compared to the classical case. This cross flow

can be deduced by investigating the mean mo mentum equation and the Reynolds stress trans port equation. Statistical evaluations have shown that all six components of the Reynolds stress tensor are nonzero.

Both the predicted cross flow and the nonzero components of the Reynolds stress tensor could be verified in a DNS at Reynolds number Re=180 for different rotation rates [5]. In this paper the re sults of a DNS at rotation rate Ro=20 at three dif ferent Reynolds numbers (Re=180, 270 and 560) are presented and discussed. The main objective of the present paper is to analyze these effects at different Reynolds numbers.

D IRECT N UMERICAL S IMULATION

Numerical Method and Computations

The numerical technique which was chosen is a standard spectral method with Fourier decompo sition in streamwise and spanwise direction as well as Chebyshev decomposition in wallnormal direction. The numerical code for channel flow was developed at KTH/Stockholm [2]. Addi tional features such as the streamwise rotation and statistics were added during the project. All flow quantities are nondimensionalized byh/2 andu cl wherehis the channel width andu cl