A numerical study on new venturi mixer design with ring-type damper to control fuel opening

Traditional industrial combustion technology is based on the diffusion combustion method. In recent years, the premixed combustion method has been widely used because it reduces fuel consumption owing to its high turn down ratio (TDR). The premixed technology uses pneumatic control to achieve high TDR and facile flow control. In this control system, the venturi mixer is a major component that controls the pressure and flow rate. The operating principle of the venturi mixer is that fuel is supplied using the negative pressure generated by high-speed air flow through a narrow flow path. At present, the major development hurdle is expanding the TDR by changing the fuel opening area in the flow path. Commercial venturi mixers are designed to open and close using a damper, which requires additional electric motors, control devices, and electric power. In this study, a noble design of a venturi mixer without electric devices is proposed on the basis of a numerical analysis. A ring-type damper with vanes is designed for the venturi mixer such that the fuel opening can be opened and closed using the drag force of air flow. As a result, the designed venturi mixer has a high TDR of 1:10 and lower pressure drop than that of commercial venturi mixers.