Prediction of Turbulent Heat Transfer in Radially Outward Flow in a Twisted-Tape Inserted Tube Rotating in Orthogonal Mode

ABSTRACT

This paper presents numerically computed pressure drop and heat transfer characteristics of turbulent developing flow in a tube rotating in orthogonal mode. The tube is fitted with a twisted tape. The flow is radially outward. Numerical predictions are obtained by solving three dimensional elliptic transport equations in a tube of length-to-diameter ratio = 14.5. Turbulence effects are captured through use of high Reynolds number form of k-ε model. It is assumed that the tube is at axially and peripherally constant wall temperature and that the tape is perfectly conducting. Numerical predictions are obtained for both clockwise and anti-clockwise tape-twist with respect to the direction of the tube axis. Axial variations of pressure drop and of Nusselt number are presented for air (Pr = 0.7) for 10000 < Re < 50000, twist ratio 3 ≤ Y ≤ ∞and Rotation number 0 ≤ Ro ≤ 0.15. Effect of Buoyancy parameter βΔT is neglected.

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