Forced-Air Direct-Contact Cooling of Airborne Electronic Equipment

A brief explanation of the principles of forced-air direct-contact cooling is given, and it is shown that the heat density of the electronic part being cooled determines essentially the range of applicability of this method. The discussion then progresses to cooling problems arising when this concept is applied to airborne electronic equipment. Several techniques are presented for obtaining high heat transfer coefficients and good air distribution with small pressure drops. The use of laminar flow in all of these techniques is shown to be effective, and examples are given of practical applications, such as the use of tube shields and special solenoid designs. Applications of thermal insulation to forced-air direct-contact cooling in aircraft are also treated, and the shortcomings, as well as the advantages of forced-air direct-contact cooling, are pointed out.