A review of flame impingement heat transfer studies .2. Measurements

This paper is the second part of a comprehensive review of flame jet impingement studies. The first part concerned the experimental conditions that were used in those studies. This part concerns the measurements that were made in those studies. Both reviews describe studies where the heat transfer to a target was measured. The geometries include flames impinging: 1) normal to a cylindrical surface, 2) normal to a hemispherically-nosed cylinder, 3) normal to a plane surface, and 4) parallel to a plane surface. Total heat flux to these targets has ranged up to 41 MW/m(2). Three steady-state methods have been used to determine the heat fluxes: uncooled target, cooled target and cooled heat flux gage. Two transient methods have been used: an uncooled target and an uncooled gage. In these studies, the gas temperatures have ranged from 292 to 3200 K. These have commonly been measured with bare wire thermocouples and I:ne reversal techniques. Measured gas velocities have ranged from 0.3-1400 m/s. These have commonly been measured with Pitot tubes and laser doppler velocimeters. The static pressure distribution near the stagnation point has been measured. This was used to determine the velocity gradient which is used in the semi-analytic heat transfer solutions. In a few studies, the thermal radiation from the flame to the target has been measured. The gas composition of the impinging jet has been measured in some of the studies. Other measurements, such as soot concentration and flame visualization, are also briefly reviewed. The advantages and disadvantages of each measurement technique are briefly considered. Recommendations for improved techniques are given.