Scaling of the propagation velocity in the contact propagation regime of stirred percolation

For regimes of flame propagation and diffusion-limited aggregation in which cluster contact is rate limiting, we find that the propagation velocity exhibits a new form of scaling related to percolation. We compute a "propagation exponent" $\psi$ and derive it in terms of static exponents. We also derive bounds on a "transport exponent" ${\psi }^{\prime }$ governing the critical diffusivity of fast tracers in lattice gases and the critical conductivity of stirred binary mixtures.