Flow and Heat-Transfer Computations in Rotating Rectangular Channels with V-Shaped Ribs

Abstract

Computations were performed to study three-dimensional turbulent flow and heat transfer in a rotating rectangular channel with V-shaped ribs. The channel aspect ratio is 4:1, the rib-height-to-hydraulic-diameter ratio e/D h is 0.078, and the rib-pitch-to-height ratio P/e is 10. A total of eight calculations have been performed with various combinations of rotation number, Reynolds number, coolant-to-wall density ratio, and channel orientation. The rotation number and inlet coolant-to-wall density ratio were varied from 0.0 to 0.28 and from 0.122 to 0.40, respectively, whereas the Reynolds number was varied from 10 4 to 5 × × 10 5 . Three channel orientations (90, − −135, and 135 deg from the rotation direction) were also investigated. A multiblock Reynolds-averaged Navier-Stokes method was employed in conjunction with a near-wall second-moment turbulence closure for detailed predictions of the mean velocities, mean temperature, turbulent Reynolds stresses, and heat fluxes.conductivity of coolant, w/(m · • C) L = total length of the channel, m L 1 = unheated smooth starting section of the channel, m L 2 = heated ribbed section of the channel, m L 3 = unheated smooth exit section of the channel, m N u = local Nusselt number, h D h /k N u 0 = Nusselt number in fully developed turbulent nonrotating tube flow Pr = Prandtl number Re = Reynolds number, W b D h /ν Ro = rotation number, D h /W b R r = radius from axis of rotation, m S = streamwise distance, m T = local coolant temperature, • C T b= bulk mean temperature, • C T w = local wall temperature, • C T 0 = coolant temperature at inlet, • C W b = bulk velocity in streamwise direction, volume flow rate/area, m/s α = rib angle β = channel orientation measured from direction of rotation ρ/ρ = inlet coolant-to-wall density ratio, (T w − T 0 )/T w θ = dimensionless temperature, (T − T 0 )/(T w − T 0 ) ν = kinematic viscosity of coolant, m 2 /s ρ = density of coolant, kg/m 3 = rotational speed, rad/s

Turbine Blade Cooling Studies at Texas A&M University: 1980-2004

“…Their heat transfer predictions were in good agreement with the experimental data of Griffith et al 59 Using the same second-moment closure model as Jang et al, 68,69 Su et al 72 computed flow and heat transfer in one-pass rotating rectangular channels (A R = 4:1) with V-shaped rib turbulators for a wide range of Reynolds numbers from 10 4 to 5 × 10 5 . Their heat transfer predictions were in good agreement with the experimental data of Lee et al 60 Figure 19 shows a comparison of the velocity vectors and temperature contours for nonrotating rectangular channels with V-shaped ribs.…”