Study of the Convective Heat Transfer in a Rotating Coolant Channel

Abstract

An experimental and theoretical study of convective heat transfer in a rotating coolant channel was inspired by the potential application to cooled turbine rotor blades. The flow that circulates into the internal cavity of the blade is subjected to Coriolis and centrifugal forces, in addition to pressure and friction forces. In this study, the channel is a rectangular-sectioned duct that rotates around an orthogonal axis. The experimental rig is composed of a vacuum enclosure, which includes an electric furnace, and the test section, heated by radiative flux. The temperatures of the wall test section are measured with thermocouples and the infrared pyrometer technique still under development. The convective heat transfer coefficients are determined with transient or steady-state techniques. It is shown that Coriolis acceleration has a beneficial influence on mean heat transfer. Locally, along the pressure side, the transfer increases strongly and on the contrary along the suction side, it decreases slightly. These effects are analyzed theoretically with a Navier-Stokes three dimensional (with mixing length model of turbulence) and explained by the influence of Coriolis force, which induces a secondary flow and distorts the velocity and temperature profiles. Experimental and theoretical results are presented and discussed.

Effect of rib height on heat transfer in a two pass rectangular channel (AR=1:4) with a sharp entrance at high rotation numbers

“…The power law function used to correlate the data is shown in Eq. (9). The corresponding coefficients and exponents for the three different cases are listed in Table 1.…”

“…This ratio is referred to as the rotation number (Ro). Guidez [9] experimentally studied the convective heat transfer in a rectangular rotating channel. He theoretically analyzed rotation effects with a 3D Navier-Stokes turbulant mixing length model.…”

A 3D-PIV System for Gas Turbine Applications

“…Correspondingly, they stabilize the flow and degrade heat transfer along the leading surface of the radially-outward leg and the trailing surface of the radially-inward leg. A factor of 2 or greater in the Nusselt numbers between trailing and leading surfaces have been reported (Guidez, 1989;Han et al, 1993;Bons and Kerrebrock, 1998). The bend-induced secondary flows direct the flow from the inner-side wall to the outer side wall producing a two-roll flow pattern (Schabacker et al, 1998), and can considerably distort the Coriolis-induced secondary flow in the near-field following the bend.…”

Experimental study of thermal development in a rotating square-ended U-bend

“…1, the passage also rotates orthogonally [1][2][3][4][5][6]. Experimental investigations focus entirely on the effects of rotation in straight ducts have also appeared [7,8]. As can also be seen in the comprehensive text book of Han et al [9], with some exceptions, most experimental studies of heat transfer in rotating U-bends provide only either average, or spot measurements of Nusselt number.…”