MONTE-CARLO PROBABILITY DENSITY-FUNCTION METHOD FOR GAS-TURBINE COMBUSTOR FLOWFIELD PREDICTIONS

A coupled Lagrangian Monte Carlo (MC) probability density function (PD F), Eulerian computational fluid dynamics (CFD) technique is presented for calculating steady three-dimensional turbulent reacting now in a gas turbine combustor, PDF transport methods model turbulence-combusti on interactions more accurately than conventional turbulence models wi th an assumed-shape PDF. The PDF was over composition only, The PDF tr ansport equation was solved using a Lagrangian particle-tracking MC me thod. This MC module has been coupled with CONCERT, which Is a fully e lliptic three-dimensional body-fitted CFD code based on pressure corre ction techniques, CONCERT calculates the mean velocity and mixing freq uency field that are required by the composition PDF in the MC module, whereas the MC module computes the PDF from which the mean density fi eld is extracted and supplied to CONCERT, This modelling approach was initially validated against Raman data taken in a recirculating bluff body stabilized flame, The computed mixture fraction and its variance (as obtained from the calculated PDF) compared very well against the c orresponding measurements made along several radial lines at different axial downstream positions and along the axis, A typical single annul ar aircraft engine combustor was also analysed, In this preliminary st udy, the flowfield, fuel, and temperature distribution were obtained b ased on the assumption of fast chemistry, The solutions obtained using the present approach were compared with those obtained using a presum ed-shape PDF method, The comparison of the calculated exhaust gas temp eratures using these two approaches with measurements made by a thermo couple rake appeared to indicate better agreement with the PDF transpo rt technique.