The goal of this work was to quantify the uncertainty in the solution of a scramjet isolator flowfield due to the uncertainty in the closure coefficients of commonly used turbulence models in Reynolds-averaged Navier-Stokes simulations. The Menter baseline, Menter shear stress transport, Spalart-Allmaras, and Wilcox-2006 k - ω turbulence models were examined; and simulations were carried out using the VULCAN flow solver. Nonintrusive polynomial chaos theory was used for efficient uncertainty propagation, and Sobol indices were employedto establish relative sensitivities of the flow solution to closure coefficients. The results obtained were compared to experimental dataaswell as toprevious work focusingon relevant flow problems. Sets of closure coefficients that contribute most to solution uncertainty for each turbulence model were identified, which warrant further investigation because more knowledge about the effects of these coefficients is expected to reduce the uncertainty in the numerical design of scramjet isolators.