[Objective] The supercritical carbon dioxide (sCO₂) Brayton cycle has become a promising power‑generation technology owing to its high cycle efficiency and compact component layout. Nevertheless, condensation phase‑change near the critical point inside centrifugal compressors severely threatens operational reliability. Severe working fluid condensation will not only lead to mass flow degradation and shrinkage of the stable operating envelope, but liquid droplet impingement upon high speed spinning blades may also trigger hidden risks concerning blade structural integrity and mechanical strength. The suction‑side leading‑edge grooving modification can mitigate local condensation, yet it introduces extra flow perturbation and aerodynamic performance degradation. It remains insufficiently understood how to coordinate the condensation‑suppression benefit and efficiency penalty brought by grooved blades. This work aims to explore the collaborative optimization between the grooved‑blade structure and inlet‑temperature adjustment for sCO₂ centrifugal compressors. 

[Methods] Numerical simulation based on computational fluid dynamics was carried out for the sCO₂ centrifugal compressor with suction‑side leading‑edge grooving. The homogeneous binary mixture model was adopted to capture two‑phase condensation behavior, while the k‑ω SST turbulence model was employed to resolve complex boundary‑layer flow and local separation. After grid‑independence examination and model validation against Sandia National Laboratory’s experimental data, the internal flow field, condensation characteristics, and overall aerodynamic performance were systematically investigated under inlet temperatures ranging from 310 K to 319 K at the fixed mass‑flow rate of 61 kg/s, which corresponds to the peak‑efficiency working point of the prototype compressor. 

[Results] The grooved‑blade configuration effectively elevates static pressure and static temperature within the core condensation zone close to the blade leading‑edge, drastically cutting the dimensionless condensation volume. However, local vortices and flow disturbance induced by the groove reduce the maximum isentropic efficiency from 84.60 % of the baseline smooth blade down to 83.20 %. Raising the inlet temperature properly compensates for such performance loss. Within 310 K‑315 K, compressor isentropic efficiency climbs continuously from 82.1 % to 83.5 %. As inlet temperature increases from 310 K to 314 K, the dimensionless condensation volume drops sharply and approaches nearly zero beyond 314 K, proving that reasonable inlet‑temperature elevation eliminates most impeller internal condensation regions. When inlet temperature exceeds 315 K, the condensation‑suppression capability barely improves further. Even so, reduced working‑fluid density impairs the pressure‑boosting capacity, leading to continuous decline of total pressure ratio and gradual deterioration of isentropic efficiency. 

[Conclusions] Balancing condensation‑control effectiveness, isentropic efficiency, and pressure‑ratio characteristics comprehensively, 315 K is identified as the optimal inlet operating temperature for this grooved‑blade sCO₂ centrifugal compressor. At this condition, the condensation risk is well restrained, and the aerodynamic penalty originating from blade grooving is largely recovered. The present findings provide practical references for blade‑structure optimization and operating‑parameter matching of sCO₂ centrifugal compressors in Brayton‑cycle power systems.