Future designs of gas turbine combustors will demand an increasingly detailed understanding of their internal flow structure. Acquisition of complete velocity field information in realistic combustor geometries under burning conditions is, however, extremely difficult, if not impossible, and recourse will always be made to the study of isothermal, constant density systems. Exact similarity between isothermal and combusting flows is clearly not possible. A question is therefore raised as to the most suitable way in which an isothermal experiment may be tailored to make it as closely as possible a simulation of the equivalent burning flow. This is the issue addressed in this paper. A can-type combustor geometry is studied; this includes a swirler-driven primary zone and two rows of radially inflowing jets. Two flow splits are considered to simulate the burning flow in a geometrically similar combustor with transply walls for cooling. The first split simulates swirler-total and primary-dilution flow ratios. The second split concentrates on swirler-primary and dilution-cross-flow ratios. Laser Doppler anemometry measurements and flow visualizations obtained in a plexiglass water model show that the first flow split results in atypical and totally unsuitable flow patterns for modelling the burning flow. The second flow split produces much improved flow patterns in both primary and dilution zones. Measurements of both axial and swirl velocity components are provided to demonstrate the acceptability of the resulting flow structure.