A new turbulent, premixed, stagnation swirl flame (SSF) is used to synthesize titanium dioxide (TiO2) nanopowders. Synthesis conditions under two flame modes, i.e., burner- and substrate-stabilized SSF, are investigated, for the same equivalence ratio, but different inert-dilution ratios. The particles (collected on the substrate) have high anatase purity, with mean diameters of 5 - 10 nm, determined using BET and TEM, for all cases studied. For the same mean nanoparticle diameter synthesized, the SSF can accommodate higher precursor loading fluxes than that produced by others using laminar premixed stagnation flat flames. Particles in the flow field are determined to be non-agglomerated. For the particles deposited on the substrate, molecular dynamics simulations support the experimental results that sintering and growth of TiO2 nanoparticles do not occur on the substrate after the deposition, and the high anatase-phase purity is maintained.