THEORETICAL SCALING LAWS FOR SUBWAY MODELING - INTERIM REPORT

THE AERODYNAMIC ANALYSIS IDENTIFIED THE DIMENSIONLESS FACTORS UPON WHICH DRAG COEFFICIENTS ARE DEPENDENT. DRAG WAS THUS COMPUTED AS A FUNCTION OF VEHICLE VELOCITY, A CHARACTERISTIC LINEAR DIMENSION (VEHICLE DIAMETER), ACCELERATION, AND FLUID PROPERTIES WHICH ARE DETERMINED BY DENSITY, VISCOSITY, AND THE SPEED OF SOUND. SCALE FACTORS ARE CALCULATED FOR BOTH FORCE AND VEHICLE MASS. THE THERMODYNAMIC ANALYSIS WAS BASED UPON THREE PARAMETERS OF HEAT TRANSFER. AS A SUBWAY TRAIN APPROACHES A STATION, HEAT IS GENERATED BY RESISTOR GRIDS IN THE BRAKING BOX. WHILE THE VEHICLE IS IN MOTION, THIS HEAT IS TRANSFERRED BY FORCED CONVECTION; AS THE TRAIN COMES TO A STANDSTILL, HEAT TRANSFER OCCURS BY FREE CONVECTION AND RADIATION. THE THERMODYNAMIC ANALYSIS ATTEMPTED TO DEVELOP SCALING LAWS FOR EACH OF THESE THREE PROCESSES. IT IS CONCLUDED THAT THE EFFECTS OF HEAT TRANSFER CAN BE EFFECTIVELY SCALED IN THE CASE OF THERMAL RADIATION. HOWEVER, THE EFFECTS OF FORCED CONVECTION COULD ONLY BE SCALED IN AN AVERAGE SENSE, AND SCALING WAS NOT POSSIBLE IN THE CASE OF FREE CONVECTION. /UMTA/

  • Supplemental Notes:
    • PROJ NO DC-MTD-7
  • Corporate Authors:

    California Institute of Technology

    1201 East California Street
    Pasadena, CA  USA  91125
  • Publication Date: 1971-3

Subject/Index Terms

Filing Info

  • Accession Number: 00242081
  • Record Type: Publication
  • Source Agency: Urban Mass Transportation Administration
  • Files: TRIS, USDOT
  • Created Date: Nov 7 1981 12:00AM