NACA Technical Notes

Report presenting burst testing conducted on several designs of sound disks and disks with defects. Results were compared with tensile strength, tensile ductility, and notch tensile strength. The main purpose of the investigation was to determine the extent to which disk strength can be increased by increasing tensile strength, to investigate the extent to which a correlation exists between disk strength and mechanical properties, and to present data on the influence of several types of stress concentration on the strength of disks made from ductile and brittle materials

Heat-and-power in industrial fermentation processes

Large-scale fermentation using genetically engineered micro-organisms has frequently been proposed as a future alternative means of obtaining bulk organic chemicals from plant and organic waste materials. Sometimes it is implied that in some way this would conserve fossil fuels, or become more attractive if petrochemical feedstock costs rose dramatically. The paper examines the energy requirements of large-scale fermentation processes, and focuses on the high power requirement. First of all it is shown that the ratio of power to heat required for fermentation and downstream processing (distillation, drying, etc.) is usually around 0·7. The high power requirement is due to the need to cool and aerate the fermenter. The primary energy required is thus high. Two means by which this can be minimised are examined--combined heat and power, and heat pumping from refrigeration equipment. An analysis of the comparative costs of the two approaches shows that with current United Kingdom energy prices energy cost savings between 15 and 30% are possible using such integrated energy systems. The combined heat and power scheme uses less fossil fuel than the alternative, but its higher capital cost makes it a longer term investment. Overall fossil fuel consumption for chemicals manufacture is shown to be similar to that of the normal synthetic routes.

NACA Technical Notes

Report presenting an investigation of the significance of tensile strength and ductility in the presence of defects and the strength-reducing effects of several types of defect were investigated for some rotating disks. Some of the defects investigated included laminar-type irregularities, eutectic melting, and shrink porosity