The combustion of liquid droplets in supersonic combustors evolves highly complex physical–chemical processes. In this study, the combustion characteristics of n-heptane dilute sprays, dynamics of individual droplets, and two-phase interactions are investigated numerically in a strut-based supersonic combustor. Air and hydrogen are injected into the combustor at Mach numbers of 2.0 and 1.0, respectively. Dilute n-heptane droplets are carried by the hydrogen jet. The combustion characteristics and droplet behaviors are simulated under different air inlet temperatures. The results reveal that the droplet evaporation, interphase exchange, and overall combustion efficiency are intensified with increased air temperature. However, excessively high air temperature may lead to incomplete combustion as fuel is swept out of the combustor by the high-speed airflow.