Spacer grids are used in nuclear reactor fuel assemblies to give mechanical support to the rods and to lower the flow-induced vibration. The fuel rods are surrounded by a circulating coolant, which aids in both heat removal and radiation protection. Mixing due to the presence of a spacer enhances the heat transfer from the fuel rod to the coolant. In the present work, to investigate the thermal hydraulic characteristics of a completely heated 7-rod hexagonal bundle with different shapes of spacers, a series of computational fluid dynamics (CFD) simulations were performed at a pressure of 70 bar. The Re-Normalization Group (RNG) \(k-\epsilon \) model is employed for fluid turbulence. The numerical investigation shows that the spacer increases the coolant mixing, which results in lower fuel rod surface temperature. The present study also shows that spacers act as a blockage, due to which there is an additional pressure drop in the region. In addition, it is found that the plate-type and sine-wave type spacer designs exhibit superior performance over the other spacer designs. An 8.90 % of reduction in wall temperature is noted for the fuel rod bundle having a plate-type spacer.