Experimental Method for Combustion Efficiency Calculation in a Reheat Duct

An efficient method for the experimental measurement of the combustion efficiency in a reheat duct has been developed at ONERA. Such a method is useful because numerous reheat tests are necessary to study the effect of geometry and flow characteristics on reheat performances. Static pressure measurements along the duct and gas sampling in its outlet cross section are the basis of this downstream-to-upstream method. Experimental results with a tri-annular V-gutter flame holder are presented. These results are also used for comparison with theoretical two-dimensional calculations applied to reheat ducts that ultimately may reduce the number of experiments necessary for the development of reheat combustion chambers.