Turbomachinery flows are widely known to be naturally unsteady, mainly due to the relative motion of rotors and stators. The stator/rotor interaction, especially, is a three-dimensional (3D) unsteady phenomenon driven by wake, shock, and blade interactions that can lead to significant periodic unsteadiness, reaching up to 50% of the mean flow values. These interaction effects, combined with inlet-temperature distortions (hot streaks) caused by non-uniformities in the combustor-exit flow temperature originating from discrete fuel-injector configurations upstream, significantly increase flow complexity. In high-pressure (HP) turbines subjected to inlet temperature distortions, strong secondary flows and the non-uniform redistribution of hot fluid across stationary and rotating rows dictate the localized aerothermal behaviour. While direct multipassage unsteady simulations that capture the full annulus provide accurate representations, they remain computationally prohibitive for practical design cycles—particularly in turbine stages with unequal blade counts. To mitigate this computational burden, this paper evaluates a single-passage numerical framework utilizing phase-shifted periodic boundary conditions to capture deterministic unsteadiness frequencies without geometric modifications. Firstly, a comprehensive grid independence study is performed using steady-state formulations; secondly, the single-passage phase-lag solver is rigorously validated against a multi-passage reference simulation; and finally, the single-passage framework is utilized to systematically investigate the aerothermal impacts of three distinct radial hot-streak alignments (hub-, mid-, and tip-aligned profiles) under adiabatic and non-adiabatic wall constraints. The results reveal critical physical insights into hot-streak migration paths, preferential blade heating, and the strong coupling between fluid thermal fields and core-stage aerodynamics.