Accession Number : ADA191003

Title :   Local Heat/Mass Transfer and Pressure Drop in a Two-Pass Rib-Roughened Channel for Turbine Airfoil Cooling.

Descriptive Note : Final contractor rept.,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION TURBOMACHINERY LABS

Personal Author(s) : Han, J C ; Chandra, P R

PDF Url : ADA191003

Report Date : Sep 1987

Pagination or Media Count : 171

Abstract : The heat characteristics of turbulent air flow in a multipass channel were studied via the napthalene sublimation technique. The naphthalene-coated test section, which consisted of two straight, square channels joined by a sharp 180 deg turn, resembled the internal cooling passages of gas turbine airfoils. The top and bottom surfaces of the test channel were roughened by rib turbulators. The rib height-to-hydraulic diameter ratio (e/D) were 0.063 and 0.094, and the rib pitch-to-height ratio (P/e) were 10 and 20. The local heat/mass transfer coefficients on the roughened top wall and on the smooth divider and side walls of the test channel were determined for three Reynolds numbers of 15,000, 30,000, and 60,000, and for three angles-of-attack alpha of 90 deg, 60 deg, and 45 deg. The results showed that the local Sherwood numbers on the ribbed-walls were 1.5 to 6.5 times those for a fully developed flow in a smooth square duct. The average ribbed-wall Sherwood numbers were 2.5 to 3.5 times higher than the fully developed values, depending on the rib angle-of-attack and the Reynolds number. The results also indicated that, before the turn, the heat/mass transfer coefficients in the cases of alpha = 60 deg and 45 deg were higher than those in the case of alpha = 90 deg. However, after the turn, the heat/mass transfer coefficients in the oblique-rib cases were lower than those in the traverse-rib case. Correlations for the average Sherwood number ratios for individual channel surfaces and for the overall Sherwood number ratios are reported. Correlations for the fully developed friction factors and for the loss coefficients are also provided.

Descriptors :   *GAS TURBINES, *HEAT TRANSFER COEFFICIENTS, *TURBULENT FLOW, *AIR COOLED, AIR FLOW, AIRFOILS, ANGLE OF ATTACK, BOTTOM, CHANNELS, COEFFICIENTS, COOLING, FRICTION, HEAT, HEAT TRANSFER, INTERNAL, LOSSES, MASS TRANSFER, PRESSURE, RATIOS, REDUCTION, REYNOLDS NUMBER, RIBS, SIDES, SUBLIMATION, SURFACES, TURBINES, WALLS, NAPHTHALENES, CHANNEL FLOW

Subject Categories : Air Condition, Heating, Lighting & Ventilating
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE