Wick-Type Liquid-Metal Combustion
Abstract
A numerical study is conducted to study lithium-sulfur hexafluoride (Li-SF6) wick diffusion flames. The objective of this study is to assess the effects of changing the geometry (height H and aspect ratio H/yo) and ambient conditions (free-stream velocity u infinity and gravity) on the burning rate and heat transfer. Wick combustion is identified as a boundary-layer gaseous diffusion flame with multiphase combustion products. A mathematical model for wick diffusion flames is established employing a conserved scalar approach. Both forced and mixed convective burning conditions are considered. Laminar, variable-property, boundary-layer equations are cast into dimensionless forms using the modified Howarth-Dorodnitzyn transformation for vertical plates and cylinders. The state relationships for the properties are taken from existing data of Li-SF6 combustion at a pressure of P = 0.01 MPa. Forced convective burning, for which the Reynolds number (Re = u infinity H/v infinity) is the important dimensionless parameter, is studied first. The results show that increasing u infinity increases the total burning rate, m. A relationship between m and Re and Re is obtained for both planar and cylindrical wicks of a given geometry (H = 100 mm, yo = 12.5 mm). The flatplate solution yields a fuel mass burning rate per unit surface area (i.e. local fuel burning rate) following the x-1/2 dependence of the classical similarity solution, where x is the streamwise distance. This dependence is not evident in the cylinder solution. Cylindrical wick geometries yield enhanced burning rates over planar wicks.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1992
- Accession Number
- ADA251539
Entities
People
- Larry Chen
- R. C. Damaso
Organizations
- University of Iowa