CENERALIZED CHARTS FOR DETERMINATION OF PRESSURE DROP OF A HIGH-SPEED COMPRESSIBLE FLUID IN HEAT-EXCHANGER PASSAGES I – AIR HEATED IN SMOOTH PASSAGES OF CONSTANT AREA WITH CONSTANT WALL TEMPERATURE

摘要

The usual approximations made in calculating the pressure changes of a compressible fluid flowing through heat-exchanger passages introduce appreciable errors in the range of high-flow Mach numbers and high rates of heating. Existing methods for obtaining accurate results over the entire Mach number and rate-of-heating range require numerical integration for each specific set of conditions and are therefore too tedious for general application.nIn the present paper an analysis is made of the compressible-flow variations occurring in heat-exchanger passages. The results of the analysis describe the flow and heating characteristics for which specific flow passages can be treated as segments of gen¬eralized flow systems. The graphical representation of the flow variations in the generalized flow systems can then be utilized as working charts to determine directly the pressure changes occurring in any specific flow passage. On the basis of these results, working charts are constructed to handle the case of air heated at constant wall temperature under turbulent-flow condi¬tions. A method is given of incorporating the effect on the heat-exchanger flow process of high temperature differential between passage wall and fluid as based on recent NACA experimental data. Good agreement is obtained between the experimental and the chart pressure-drop values for passage-wall average temperatures as high as 1752° R (experimental limit) and for flow Mach numbers ranging from 0.32 to 1.00 (choke) at the passage exit.