The study of the drying of Buna S.

A study of the drying of Buna-S in crumb form (designated as GR-S) is presented in which investigations of vacuum and air drying are made. The drying characteristics are presented and the effect of drying on the quality is evaluated. Vacuum drying is investigated using a shelf and a rotary type unit. The individual effects of temperature, vacuum, thickness of crumb layer, and size of crumb particles are studied. Data are correlated by means of drying rate curves. Comparisons of the effects of the variables are made using these curves. Air drying is studied by the use of a shelf unit with air blowing across the crumb. Air drying also is investigated with air directed through the bed of crumb. The variables studied are: temperature, humidity, air velocity, thickness of crumb layer, size of crumb, and shrinkage of the crumb during drying. The results are presented as drying rate curves and comparisons are made showing the effect of variables. A study of the temperature of the rubber during drying is presented showing the trend as the moisture content changes. The quality of the dried rubber is determined by means of an evaluation of the gel content. The gel content is defined as the per cent of the rubber insoluble in benzene. The results of several studies of the effect of temperature on the formation of gel are presented

The Design of a High-Q, MACH-5 Nozzle for the Langley 8-Foot HTT

A new nozzle has ben designed for the NASA Langley Research Center 8-Foot High Temperature Tunnel. The new nozzle was designed with a Mach-5 exit flow at a Mach-5 flight-enthalpy test condition and has a smaller throat area than the existing Mach-5 nozzle which significantly increases the range of dynamic pressures that can be achieved in the facility. The nozzle was designed using the NASA Langley IMOCND computer program which solves the potential equation using the classical method of characteristics. Several axisymmetric nozzle contours were generated and evaluated using viscous computational fluid dynamics. A number of items were considered in the evaluation, including flow uniformity, thermal and structural design, manufacturing schedule and cost. Once the final contour was selected, studies were done to determine the effects of manufacturing irregularities (steps and cavities at joints). These studies were done to develop manufacturing specifications and assembly tolerances