Point-conditioned sampling is applied to single-point measurements of scalars and velocity components in a turbulent hydrogen diffusion flame and an air jet, both issuing into co-flowing air. The fuel element concentration signal (obtained by a Mie scatter technique from the seeded nozzle stream) is used to identify the appearance of turbulent excursions in intermittent regions of the flow. Point ensemble averages are determined for excursions of different duration and the fluctuations are decomposed into superposed and large-scale motions. It is found that the large-scale motion in the flame has a signature much like that found in non-reacting jets, with steep gradients at the leading edges for both velocity and scalars. The turbulence of the flame is seen to be more anisotropic than in the air jet both for superposed and large-scale motions. The contribution of large-scale fluctuations to overall turbulent kinetic energy and radial fluxes is smaller for the flame than for the air jet, and it appears that the superposed motion dominates in both flame and air jet.
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