Abstract: The separation process of walnut shell and kernel is the first crucial step in the deep processing production flow of walnuts.Wind separation has become one of the main methods for walnut shell-kernel separation due to its stable effect, high efficiency, and small damage caused to the kernel, and the key to wind separation is the study of aerodynamic characteristics of walnut shell-kernel and the measurement of related parameters. Addressing the issues of irregularity in walnut shell and kernel materials and the difficulty in accurately measuring key parameters of their aerodynamic characteristics, this paper employs a method that combines simulation analysis with interval estimation to study the aerodynamic properties of walnut shell and kernel materials and conducts experiments. Initially, the study adopted the CFD-DEM(Computational fluid dynamics, Discrete element method) method, and the finite element software ANSYS Fluent was used to construct the flow field, and based on the method of filling small particles in the discrete element software EDEM to establish the discrete element model of the shell kernel material, and simulated the movement of the shell kernel material in the airflow. Based on the motion trajectories of the materials and the velocity distribution of the flow field, the suspension velocity range for six types of materials, such as one-half shells, one-quarter shells, one-eighth shells, one-half kernels, one-quarter kernels and one-eighth kernels, is determined. Subsequently, using the simulation results as a reference, an experimental bench is constructed. During the bench tests, high-speed photography technology is utilized to record the motion of the shell and kernel materials, and a statistical analysis of the distribution of materials in different wind speed ranges is conducted. After K-S testing, it is found that the position distribution of the six types of materials in the airflow within the cavity follows a normal distribution pattern. Finally, Origin data processing software was used to perform Gaussian fitting based on the statistical data of various types of materials, and the range of levitation speeds of various types of materials was statistically derived based on the interval estimation method: 7.25-9.50 m/s for one-half shells, 6.90-8.95 m/s for one-quarter shells, 6.20-7.75 m/s for one-eighth shells, 9.20-14.85 m/s for one-half kernels, 9.60-14.55 m/s for one-quarter kernels and 9.30-11.45 m/s for one-eighth kernels. Through the analysis of experimental data, the optimal wind selection speed range for shell and kernel air separation equipment is determined to be 9.0～9.4 m/s. Additionally, the theoretical formula for suspension velocity is corrected, and the shape correction coefficients applicable to Yunnan Yangbi walnuts are obtained as follows: 3.82 for one-half shell, 3.06 for one-quarter shell, 2.80 for one-eighth shell, 1.49 for one-half kernel, 1.12 for one-quarter kernel, 1.17 for one-eighth kernel. Furthermore, this study combines the phenomena and data from simulation and bench experiments to investigate and analyze the causes of shell and kernel stacking phenomena and their potential impact on wind selection separation efficiency. The results indicate that increasing the rotational motion of shell and kernel materials in the airflow can reduce the frequency of stacking phenomena, which helps to improve the separation efficiency of mixed shell and kernel materials. The suspension velocity interval estimation method proposed in this paper can provide a reference for the aerodynamic characteristic analysis and key parameter measurement of irregular agricultural materials.