  The present paper reports on the numerical investigation of lifted turbulent
jet flames with H2/N2 fuel issuing into a vitiated coflow of lean combustion
products of H2/air using conditional moment closure method (CMC). A 2D
axisymmetric formulation has been used for the predictions of fluid flow, while
CMC equations are solved with detailed chemistry to represent the
turbulence-chemistry interaction. Simulations are carried out for different
coflow temperatures, jet and coflow velocities in order to investigate the
impact on the flame lift-off height as well as on the flame stabilization.
Furthermore, the role of conditional velocity models on the flame has also been
investigated. In addition, the effect of mixing is investigated over a range of
coflow temperatures and the stabilization mechanism is determined from the
analysis of the transport budgets. It is found that the lift-off height is
highly sensitive to the coflow temperature, while the predicted lift-off height
using the mixing model constant, i.e., C{\Phi}=4, is found to be the closest to
the experimental results. For all the coflow temperatures, the balance is found
between the chemical, axial convection and molecular diffusion terms while the
contribution from axial and radial diffusion is negligible, thus indicating
auto-ignition as the flame stabilization mechanism.
