Vibrational relaxation effects in turbulent compressible shear layers are studied using the CFD solver US3D. Three different convective Mach numbers are examined, with varying vibrational relaxation rates. The effects of vibrational relaxation are to damp the mean temperature as energy is transferred from the translational mode to the vibrational mode. As the vibrational relaxation rate is increased, the momentum thickness are damped. The underlying physical explanations behind these observations are currently being quantified.