Experimental and Numerical Study of Ramp Injectors for Supersonic Fuel/air Mixing.
The planar laser-induced iodine fluorescence (PLIIF) measurement technique has been improved and automated so that mapping of complex three-dimensional compressible flowfields can be accomplished with improved accuracy and speed. The PLIIF technique is used to measure pressure, temperature, velocity and injectant mole fraction in two nonreacting ramp fuel injector flowfields: (1) Mach 1.7 injection from a swept ramp into a Mach 2.0 freestream and (2) Mach 2.0 injection from an unswept ramp into a Mach 2.9 freestream. The ramp injectors tested are configurations being considered as enhanced fuel/air mixing schemes in scramjet engine combustor designs. Measurement uncertainties are strong functions of the local thermodynamic properties but are in the range of about 4% to 7% for all the properties measured in the flowfields studied here. Detailed plane by plane comparisons are made to CFD simulations using the three-dimensional version of the SPARK Navier-Stokes solver in the swept ramp flowfield. The comparisons provide useful information about the strengths and weaknesses of both the experimental and numerical techniques. The ability of the numerical simulation to capture complex flow features, such as separation zones, 3-D shock wave geometries, convection of vortices, is demonstrated and quantified. The unswept ramp data set is more extensive and contains numerous planes in both the crossflow and axial directions, so that quantities, such as mass, momentum and energy conservation, mixing efficiency and total pressure integrals, can be evaluated. The extensive data sets contribute important validation test cases for the SPARK code and other numerical CFD simulations in complex, three-dimensional compressible flowfields.
- Pub Date:
- January 1995
- Engineering: Aerospace; Physics: Fluid and Plasma; Engineering: Mechanical