Method for Calculation of Heat Transfer in Laminar Region of Air Flowing Around Cylinders of Arbitrary Cross Section (including Large Temperature Differences and Transpiration Cooling)


Book Description

A method which permits approximation of local heat-transfer coefficients in the laminar-flow region around cylinders of arbitrary cross seciton from those wedge-type profiles is extended to include the effects of large temperature differences and transpiration cooling. Charts prepared from exact solutions of the laminar boundary-layer equations for wedge-type profiles which allow for these effects yield results with a minimum of calculation. Application of the method to circular and elliptic transpiration-cooled cylinders is made to determine local heat transfer coefficients and surface temperatures and to determine the variation in coolant flow required for maintaining a constant surface temperature.
















A Study of the Transient Behavior of Shock Waves in Transonic Channel Flows


Book Description

The accuracy of the result obtained in a fundamental paper by Kantrowitz (NACA TN 1225) that a small short-time lowering of the back pressure in steady, shock-free, transonic diffuser flow causes a stationary or trapped shock to form near the critical sonic channel throat is investigated by considering the contribution of a higher-order term in the short-time calculations which was neglected in Kantrowitz's paper. In this higher approximation to the short-time effects, the shock is no longer stationary or trapped unless it is supported by a negative steady-flow back pressure; the result thus is no long in disagreement with steady-flow solutions for stationary shocks.




Corrosion of Metals of Construction by Alternate Exposure to Liquid and Gaseous Fluorine


Book Description

The corrosion of 3S-0 and 52S-0 aluminum, AISI 347, and 321 stainless steels, "A" nickel, and low-leaded brass has been determined from the weight change of specimens exposed alternately to liquid and gaseous fluorine. Experiments were continued for a total exposure time up to 3 1/2 months. It was found that corrosion is negligible under the conditions of the experiments. No visual differences were observed between those surfaces exposed to the gaseous phase only and those exposed to both the liquid and the gaseous phases.




WADC Technical Report


Book Description




Behavior of Materials Under Conditions of Thermal Stress


Book Description

A review is presented of available information on the behavior of brittle and ductile materials under conditions of thermal stress and thermal shock. For brittle materials, a simple formula relating physical properties to thermal-shock resistance are derived and used to determine the relative significance of two indices currently in use for rating materials. The importance of simulating operating conditions in thermal-shock testing is deduced from the formula and is experimentally illustrated by showing that BeO could be both inferior or superior to Al2O3 in thermal shock depending on the testing conditions. For ductile materials, thermal-shock resistance depends upon the complex interrelation among several metallurgical variables which seriously affect strength and ductility. These variables are briefly discussed and illustrated from literature sources. The importance of simulating operating conditions in tests for rating ductile materials is especially to be emphasized because of the importance of testing conditions in metallurgy. A number of practical methods that have been used to minimize the deleterious effects of thermal stress and thermal shock are outlined.




Index of NACA Technical Publications


Book Description