In order to reduce the pressure loss of 150-caliber swirl meter

two programs of increasing the lead of swirler and the throat diameter of casing were adopted to improve the performance of swirl meter. In the flow range from 120 m3·h-1 to 2100 m3·h-1

numerical simulation and experiment were conducted to study the pressure loss characteristics and meter factor of the swirl meter before and after improvement

and internal flow characteristics of the section where piezoelectric sensors were located was analyzed. Through numerical simulation it was found that these two programs could reduce the pressure loss of swirl meter

but meter factor decreased with degraded precision. Small flow measurement could not be applicable because of the decrease of meter factor. If only considering the factor of pressure loss

program B (increasing the lead and the throat diameter) was better than the program A (only increasing the lead). The experiments were performed on sonic nozzle device to verify simulation results of two programs. The experimental results of pressure loss and meter factor basically agreed with numerical simulation results.