Effect of single and multiple protrusions on thermal performance of slot jet impingement with curved surface

•The effect of single protrusion on average Nusselt number is not significant.•A heat transfer is more sensitive to recirculation bubble than a restriking of jet.•Arrangement of multiple protrusion can enhance or degrade the thermal performance.•A larger protrusion significantly reduces the size of recirculation bubble.•An increase in the Reynolds has positive impact irrespective to protrusion size.