The radiative heat transfer characteristics of the dimethyl ether (DME)/air jet diffusion flame (JDF) were experimentally and theoretically studied in this paper. A series of fuel nozzle diameters (d(f)), fuel jet velocities (u(f)), and air co-flow velocities (u(co)) were investigated for their influences on the thermal radiation behavior individually. The results showed that the DME jet diffusion flame length was independent of uco, but the flame width decreased exponentially with the increase in uco. Besides, new correlations for the DME jet diffusion flame width were developed in this paper. In the laminar regime, the radiation fraction (chi(R)) was nearly constant with the increase in fuel jet Reynolds number (Re-f). In the transitional regime, it increased with Ref. In the turbulent regime, it began to decrease gradually with Ref. Additionally, chi(R) increased gradually with the increase in df. As uco was increased, chi(R) decreased because of the reductions in flame width and volume. Empirical correlations between chi(R) and the operational parameters, including df, Ref, and uco, were developed in this paper to predict the radiative heat flux (RHF) at any position and incident angle outside the DME JDF, in conjunction with the weighted multi-point source model (WMP model). Besides, at any cylindrical surface around the flame, the RHF peaked at about x = 0.7 L-f. At a smaller radius, the axial RHF profile was characterized by larger axial gradients and higher global values. Additionally, the RHF distribution in the near-field (x/L-f < 2, R/L-f < 2) of small-scale flames was self-similar. Based on this behavior, a simplified method for predicting the local RHF was proposed. While with respect to the large-scale flames or far-field (x/L-f > 2 or R/L-f > 2) of the small-scale ones, self-similarity of the local RHF distribution was invalid. In such cases, the RHF was suggested to be calculated by the WMP model with the atmospheric transmissivity. (C) 2015 Elsevier Ltd. All rights reserved.