Abstract: Numerical simulations were carried out for the unsteady flow behavior of the hypersonic type Ⅳ shock-shock interactions acting on a blunt leading edge that represented the cowl of a two-dimensional hypersonic inlet. The complex wave structures and surface heat flux/pressure created by the unsteady type Ⅳ shock-shock interactions were effectively captured by solving the laminar compressible Navier-Stokes equations via a two-dimensional axisymmetric Vectorized Adaptive Solver (VAS2D). The VAS2D solver is based on an explicit finite volume method with an adaptive mesh technique and it has second order accuracy in both time and space. The present simulations focus on the effects of the location and strength of the impinging shock together with the geometry of the blunt body on the unsteady characteristics of the type Ⅳ shock-shock interactions. The results show that the flow can be either steady or unsteady depending on both the variations of the impinging shock conditions and the blunt body geometries. The unsteady characteristics of flowfield structure and surface pressure/heat flux are also sensitive to the impinging shock conditions. Small changes in the location or strength of the impinging shock can result in large changes in the unsteady behaviors of the flow and the surface pressure/heat flux. The Strouhal number was used to characterize the unsteady oscillation behavior of the flow. Under the conditions in the current work, with the increases of the impinging shock strength and the bluntness of the leading edge, the Strouhal number that is mainly dependent on the standoff distance of the bow shock decreases, whereas the surface pressure/heat flux increase. Furthermore, properly choosing the geometry of the blunt body may greatly reduce the probability of the happening of the type Ⅳ shock-shock interactions, suppress the shock oscillation in the flow, and effectively reduce the peak value of the fluctuating surface heat flux and pressure loads.