We investigate the flame ignition and propagation behaviors in a thermonuclear X-ray burst on the surface of an accreting neutron star. We present multi-dimensional hydrodynamical simulations of the flame structure evolved in real-time, without any artificial boosting of the flame speed. Hydrodynamics, nuclear reactions, thermal conductivity, and adaptive mesh refinement techniques are all incorporated in order to fully resolve the flame structure. The simulations implement varied initial conditions in neutron star temperature and rotation rate in order to explore the impact on flame ignition and propagation. We find that at low rotation rates, the flame struggles to ignite. At high temperatures, the entire fuel layer ignites and produces a simmering effect, indicative of very high accretion rates and a heated fuel layer.