Radiator Design and Installation - II, Special Report

A mathematical analysis of radiator design has been made. The volume of the radiator using least total power has been expressed in a single formula which shows that the optimum radiator volume is independent of the shape of the radiator and which makes possible the construction of design tables that give the optimum radiator volume per 100-horsepower heat dissipation as a function of the speed, of the altitude, and of one parameter involving characteristics of the airplane. Although, for a given set of conditions, the radiator volume using the least total power is fixed, the frontal area, or the length of the radiator needs to be separately specified in order to satisfy certain other requirement such as the ability to cool with the pressure drop available while the airplane is climbing. In order to simplify the specification for the shape of the radiator and in order to reduce the labor involved in calculating the detailed performance of radiators, generalized design curves have been developed for determining the pressure drop, the mass flow of air, and the power expended in overcoming the cooling drag of a radiator from the physical dimensions of the radiator. In addition, a table is derived from these curves, which directly gives the square root of the pressure drop required for ground cooling as a function of the radiator dimensions, of the heat dissipation and of the available temperature difference. Typical calculations using the tables of optimum radiator volume and the design curves are given. The jet power that can be derived from the heated air is proportional to the heat dissipation and is approximately proportional to the square of the airplane speed and to the reciprocal of the absolute temperature of the atmosphere. A table of jet power, per 100 horsepower of heat dissipation at various airplane speeds and altitudes is presented

NACA Advanced Restricted Reports

Report presenting the performance of several internally finned radiators and a comparison with more conventional honeycomb radiators. In a typical case, the new radiator can be designed with 55 percent less volume and 18 percent less power expenditure while dissipating the same amount of heat

NACA Special Reports

"A mathematical analysis of radiator design has been made. The volume of the radiator using least total power has been expressed in a single formula which shows that the optimum radiator volume is independent of the shape of the radiator and which makes possible the construction of design tables that give the optimum radiator volume per 100-horsepower heat dissipation as a function of the speed, of the altitude, and of one parameter involving characteristics of the airplane. Although, for a given set of conditions, the radiator volume using the least total power is fixed, the frontal area, or the length of the radiator needs to be separately specified in order to satisfy certain other requirement such as the ability to cool with the pressure drop available while the airplane is climbing" (p. 1)

NACA Advanced Confidential Reports

"The equations that describe the operation of a heat exchanger - the equations for pressure drop, rate of heat transfer, and power expenditure - have been put into nondimensional, generalized form. These generalized equations can be used for constructing selection charts for various types of aircraft heat exchangers. Such charts would facilitate choice of heat-exchanger dimensions for any given set of operating conditions. A typical selection chart is presented" (p. 1)

NACA Advanced Restricted Reports

Report presenting a generalized selection chart for tubular cross-flow intercoolers and another chart for Harrison cross-flow intercoolers. The charts make it easier to select intercoolers for any particular set of design conditions and under limitations on dimensions and pressure drops