The analysis of the velocity distribution and particle trajectoryare the key point of the present investigation. In Fig. 20,it is remarkable acceleration between blade outlet and outcylinder indicating the strong influence of high-speed rotating impeller. Moreover, the structure of diffuser prevents the COFenters directly the GVE region after leaving the impeller zone.Thus, it improves the conversion efficiency for dynamic pressureto static pressure, which is beneficial to the increasing residencetime of grease particles and separation efficiency of the novelrange hood.The grease particle trajectory in the novel range hood is shownin Fig. 21. Particle tracking will stop when it reaches the trapboundary. Therefore, the reduced number of particle trajectoriesmeans that they have been captured on inner surface of the novelrange hood. As in Fig. 21, the largest number of particle trajectoryappears at the novel range hood entrance, but there is remarkabledecrease after the grease particles pass through the impellerregion. It indicates that more than 50% of grease particles is separatedby the high-speed rotating impeller blades. Another part ofparticles is captured on inner surface of the out cylinder. Only afew particles can reach the GVE zone, and either captured on guidevanes surface or escape from the novel range hood outlet. Thisresult indicates the novel range hood optimised in this study exhibitsexcellent separation performance.