Numerical study and experimental validation of a Roots blower with backflow design

A three-dimensional computational fluid dynamics (CFD) model of a Roots blower with a backflow design was established to analyse the effects of the backflow on the Roots blower's performance. A prototype of Roots blower with a backflow design was manufactured to validate the CFD model through the pressure distribution and the mass flow rate. The results showed that the proposed CFD model agreed well with the experimental data. The effects of the sizes and directions of the backflow passage on the Roots blower's performance were then investigated using the validated CFD model. It was found that under a properly sized backflow passage, the pressure pulsation and the shaft power can be decreased by 80% and13%, respectively; However, the mass flow rate was reduced by 12% under the same size of backflow passage. Although the direction of the backflow passage affected the shaft power, it had no effect on the mass flow rate or pressure pulsation. The shaft power consumption of a Roots blower with a vertical backflow was 4% lower than a horizontal backflow.