In wavefront sensorless (WFSL) adaptive optics, the intensity image in the observation plane, instead of the wavefront sensor, is utilised to estimate the input aberration. The number of intensity measurements is critical for applications with ever-changing phase aberration, such as astronomical imaging. This paper details two direct WFSL methods that need a fixed number of intensity measurements to estimate the input aberration. The proposed methods adopt a zonal approach rather than a modal one to estimate the phase aberration. Simulation results demonstrate that after applying the proposed methods, the aberration correction percentage can rise by approximately 70% for large aberrations.