Computation of flow and heat transfer in rotating rectangular channels with angled rib turbulators for gas turbine blade.

摘要

Numerical prediction of three-dimensional flow and heat transfer was performed for four cases. (1) A rotating/non-rotating smooth two-pass rectangular channel (AR = 2) with a 180° turn in which the rotation number was varied from 0 to 0.22, inlet coolant-to-wall density ratio was varied from 0 to 0.22. The computation results were compared with the experimental data. (2) A rotating/non-rotating two-pass rectangular channel (AR = 2) with 45° angled ribs in which the rib height-to-hydraulic diameter ratio (e/D_h) was 0.094 and the rib pitch-to-height ratio (P/e) was 10. The rotation number (Ro) was 0.11 and the inlet coolant-to-wall density ratio (Δρ/ρ) was 0.115. The computation results were compared with the experimental data. (3) A rotating/non-rotating smooth rectangular channel with an aspect ratio of 4:1. (4) A rotating/non-rotating rectangular channel (AR = 4) with 45° angled ribs in which the rib height to hydraulic diameter ratio ( e/D_h) was 0.078. The rotation number and the inlet coolant-to-wall density ratio (Δρ/ρ) in case 3 and 4 were 0.14 and 0.122 respectively. The computation results of case 3 were compared with the experimental data. The Reynolds number in all of the above cases was fixed at 10,000. Moreover, the effect of the channel orientation in all of the above cases was studied via two channel orientations, namely β = 90° (corresponding to the mid-portion of a turbine blade) and β = 135° (corresponding to the serpentine passages in the trailing edge region of a blade).; A multi-block numerical method was employed together with a chimera domain decomposition technique to calculate the three-dimensional flow and heat transfer in a curvilinear, body-fitted coordinate system. The finite-analytic method was used to solve the Reynolds-Averaged Navier-Stokes equation in conjunction with a near-wall second-order Reynolds stress (second-moment) closure model.