Accession Number : ADA296193

Title :   Applications of Dimensionless Variables to Scaling in the Infrared.

Descriptive Note : Final rept.,

Corporate Author : NAVAL SURFACE WARFARE CENTER CARDEROCK DIV SILVER SPRING MD

Personal Author(s) : Cervenka, Peter O. ; Massa, Lou

PDF Url : ADA296193

Report Date : JAN 1995

Pagination or Media Count : 31

Abstract : The scaling laws that are useful in the design of IR ship experiments based on scaled models are reviewed. Such experiments require control of a set of dimensionless variables. Replication of ship IR contrast by scale models requires equality between the dimensionless variables of a full-scale ship and its scaled model. A particular scaling error can be expected to occur when modeling a long ship with a thin hull. In such a case, if a scale of length is chosen that makes the model a convenient laboratory length, the same scale applied to the hull cross-section may reduce it to one that is extremely thin, thus increasing costs and experimental inconvenience. A possible solution to such difficulties is presented based on using different scales for model hull length and thickness. The validity of employing two such scales of length depends upon the approximation that heat flux parallel to the hull may be neglected in comparison to that orthogonal to the hull. The design of scaled models for the IR requires a choice of structural materials with suitable thermodynamic properties. Which thermodynamic properties are relevant are pointed out by examining the form of the controlling dimensionless variables. These include the thermal conductivity, mass density, specific heat, convective heat transfer coefficient, and emissivity. These properties are collected here in a convenient set of tables and one consistent set of units. (MM)

Descriptors :   *INFRARED RADIATION, *THERMODYNAMIC PROPERTIES, *SHIP HULLS, METALS, DENSITY, THICKNESS, CONTRAST, NAVAL VESSELS, SCALE MODELS, AIR, WATER, ALLOYS, VARIABLES, NONMETALS, COSTS, ERRORS, SCALING FACTOR, THERMAL CONDUCTIVITY, CONVECTION(HEAT TRANSFER), DIFFUSIVITY, HEAT FLUX, SPECIFIC HEAT, CONSTRUCTION MATERIALS, EMISSIVITY, HEAT TRANSFER COEFFICIENTS.

Subject Categories : Marine Engineering
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE