Numerical investigation of powder dispersion mechanisms in Turbuhaler and the contact electrification effect

•A CFD-DEM model was developed to investigate powder dispersion in Turbuhaler.•Contact potential difference (CPD) between particles and wall was introduced to study the tribo-electrification effect.•Both chamber and spiral mouthpiece played important roles in powder dispersion.•Device performance was improved with higher flow rates.•Particle charge increased with higher flow rates and higher CPD, but its effect on powder dispersion was minimum.