Heat Transfer In Guns Determination Of Friction Factor From Heat Input Measurements PDF Download

An extensive invstigation of gun barrel wear and its control in hypervelocity guns was sponsored by the National Defense Research Committee during World War II. A key element in that investigation was a technique to compute heat transfer to the gun barrel wall from the hot, propellant combustion gases. An interior ballistics scheme by Nordheim and coworkers at Duke University used the Reynolds analogy between heat transfer and momentum transfer to obtain a convective heat transfer coefficient. Nordheim noted that the Reynolds analogy produced a heat transfer coefficient in which the friction factor was the only quantity to be deduced from the interior ballistics. Nordheim also showed how the friction factor could be determined experimentally with fast-response thermocouples welded near the bore surface. Nordheim used heat input from a machine gun to set constants for friction factor estimation. The heat input measurements Nordheim advocated have been in use the past several years to assess wear-reducing liners, but not yet to compute friction factors. In this report heat transfer data from a 105mm M68 tank gun and a 155mm M185 howitzer are used to compute friction factors. These friction factors are then compared to Nordheim's values as well as test Nordheim's assumption that the friction factor depends only on bore diameter.