Numerical Study On The Flow Field Inside A Centrifugal Impeller With Slotted Blade

In this paper, based on an centrifugal impeller with slotted blade, the application of numerical simulation method was used to study on influence on the flow field and performance of impeller when two long and short blades were arranged for the different deflection angleθon original shape lines; the difference of blade′s surface limiting streamline pattern,blade′s surface static pressure distribution,flow separation condition and the relative speed and pressure distribution of flow channel were analyzed; that flow separation region,wake region and slotted jet region were influenced by changing of the short blade deflection angle was explored.The technology of slotted blade was applied for the design of the centrifugal impeller, which was that long blade was disconnected and divided into two long and short blades of pre and post, two blades were arranged for dislocation on shape lines of original blade and shaped narrow lapping clearance on cohesion location. The results showed the flow situation of centrifugal impeller was improved effectively by this technology, efficiency was increased by 3.5%, total pressure was increased by 1.7%. If this technology of slotted blade was well applied in engineering, it had significant energy saving meaning. Therefore, in order to make the relative effort of influencing factors clear, this technology need to be further reseached.The results showed that the long blade flow field and blade load were nearly not influenced by short bladeθangle. When the deflection angle was turned in the positive, the load of short blade was increased with the increase ofθangle; there was separation flow on suction surface of short blade at the angle +3.5°≤θ≤+21°. When the deflection angle was turned in the negative, the load of short blade was decreased with increase ofθangle; owing to contraction of slotted channel , the high speed jet was shaped when airflow passed by flow channel , the boundary layer thickness of suction surface of short blade was weakened and separation flow was suppressed , thus the pressure ratio and efficiency were increased, Respectively the relative total pressure ratio reaches its maximum of 1.266 at theθangle of -3.5°and the isentropic efficiency reaches its maximum of 91.2% at theθangle of -7°. Some research results showed that the application of the slotted blade's technology promised to improve the blade's condition of adhesion and wear by transportation of humid and containing dust airflow.