EFFICIENT FANS AND BLOWERS

THE STATED OBJECTIVE OF TOPIC NUMBER AF88-213 IS TO "INVESTIGATE AND RECOMMEND NEW BLOWER DESIGNS TO INCREASE AIR FLOW AT LOWER POWER REQUIREMENTS." A GOAL OF GREATER THAN 80% EFFICIENCY IS ESTABLISHED. THE STATEMENT THAT "SEVERAL MODULES SHOULD BE CAPABLE OF VENTILATING AN UNDERGROUND SPACE OF 30 MILLION CUBIC FEET AT DEPTHS UP TO 6000 FEET" WOULD INVOLVE BLOWERS CAPABLE OF PRESSURE IN THE TEN TO TWENTY POUND PER SQUARE INCH RANGE AND A TOTAL AIR FLOW (BY SEVERAL MODULES) OF AS HIGH AS 500,000 CUBIC FEET PER MINUTE. WE WILL RECOMMEND AN ENTIRELY NEW DESIGN WHICH HAS BEEN UNDER DEVELOPMENT BY OUR GROUP FOR SEVERAL YEARS. THE DESIGN COMBINES THE BEST FEATURES OF POSITIVE DISPLACEMENT (VOLUME REDUCTION) AND DYNAMIC (VELOCITY PRESSURE) IN SUCH A WAY THAT ADIABATIC EFFICIENCY HIGHER THAN 85% HAS ALREADY BEEN ACHIEVED IN A PROTOTYPE OF APPROXIMATELY 350 C.F.M. AT PRESSURES FROM 5 PSIG TO 35 PSIG. THE DESIGN LENDS ITSELF TO VERY LARGE MACHINES OF SEVERAL THOUSAND CUBIC FEET AIR CAPACITY AND AT STILL HIGHER EFFICIENCY DUE TO THE SCALE EFFECT. THE OPTIMUM SPEED OF LARGE UNITS WOULD FAVOR DIRECT DRIVE BY LARGE DIESEL ENGINES OR ELECTRIC MOTORS.