AN EXPERIMENTAL STUDY OF AERODYNAMICS OF VEHICLES TRAVELING AT HIGH SPEEDS THROUGH LONG TUBES

AN EXPLORATORY EXPERIMENTAL STUDY OF THE AERODYNAMIC RESISTANCE OF MODELS MOVING THROUGH LONG TUBES WAS CONDUCTED. FOR PROPER VEHICLE DESIGN, AN UNDERSTANDING OF THE AERODYNAMIC INTERACTION BETWEEN THE ENCLOSURE AND THE VEHICLE IS NECESSARY, SINCE THE POWER REQUIRED AND THE STABILITY OF PARTICULAR CONFIGURATIONS ARE DIRECTLY RELATED TO THE VEHICLE AERODYNAMICS. POWER REQUIREMENTS ARE FUNCTIONS OF VEHICLE SIZE, SHAPE, AND BLOCKAGE RATION AS WELL AS VEHICLE SPEED AND TUBE AIR DENSITY. RESULTS ARE PRESENTED OF THE AERODYNAMIC RESISTANCE OF MODEL VEHICLES AS A FUNCTION OF LENGTH TO DIAMETER RATIO AND BLOCKAGE. THE DRAG PROGRAM WAS ORIENTED TOWARD MODELS MOVING AT SPEEDS BELOW 150 FEET PER SECOND. IN THIS SPEED REGIME, AN INCOMPRESSIBLE FLOW THEORY WHICH USES A FRICTION FACTOR AND A HYDRAULIC LOSS COEFFICIENT HAS BEEN SHOWN TO ADEQUATELY PREDICT THE AERODYNAMIC DRAG OF VEHICLES WITH BLOCKAGE RATIOS UP TO 0.7. AS AN ILLUSTRATION OF THE USE OF THIS THEORY, THE REQUIRED HORSEPOWER IS SUMMARIZED FOR A 10-FOOT DIAMETER VEHICLE, 300 FEET LONG, OPERATING UNDER SEVERAL DIFFERENT CONDITIONS. TUBE WALL PRESSURE MEASUREMENTS WERE OBTAINED WHICH ARE PERTINENT TO THE UNDERSTANDING OF VEHICLE MOTION IN A TUBE.