Laminar Flow Gas Turbine Regenerators--The Influence of Manufacturing Tolerances

Several current designs for high effectiveness gas turbine regenerators involve low Reynolds No. fully-developed laminar-flow type surfaces. Such surfaces consist of cylindrical flow passages, of small hydraulic radius, in parallel and the cylinder geometry may, as examples, be triangular, as in some glass-ceramic surfaces, or rectangular, as in deep-fold metal foil surfaces. This presentation demonstrates that manufacturing tolerances of several thousandths of an inch in passage dimension have a significant influence on the overall heat transfer and flow friction behavior. The analysis is also useful in rationalizing the difference between theory and test results for the basic heat transfer (j factor) characteristics as a function of Reynolds No. for various surfaces of the laminar-flow type. (Author)