Research Of Blade Thickness Variation Impact On Performance Of Centrifugal Pump

Pump as a general machinery, the mechanical energy is converted to kinetic energy and pressure to the liquid plays a very important position in the national economy. Its energy consumption accounts for about 20% of the national electricity generation, research to improve the performance of important practical significance.Impeller is an important over-current and acting components of the pump, the impeller of the axial plane, the blade profile and the blade thickness variation of greater impact on the performance of the pump. With the impeller axial plane, blade profile impact on the performance of the centrifugal pump some scholars have researched, but the blade thickness variation on the performance of centrifugal pumps rarely seen reports in the literature. Therefore, there is necessary to study the blade thickness variation on the centrifugal pump performance.In this paper, three different specific speed ( n_s= 49.9, 97.8, 187.9) based on oil chemical pump, the impeller to ensure the same axial parameters designing nine types of thickness airfoil according to three types of blade thickness variation. For ( n_s= 49.9) low specific speed centrifugal pump, designing three types of thickness airfoil T1,T2,T3 obtaining three centrifugal pump programs:program one,program two,program three;For ( n_s= 97.8) the central specific speed centrifugal pump, designing three types of thickness airfoil T4,T5,T6 obtaining three centrifugal pump programs:program four,program five,program six; For ( n_s= 187.9) the high specific speed centrifugal pump, designing three types of thickness airfoil T7,T8,T9 obtaining three centrifugal pump programs:program seven,program eight,program nine. The use of UGNX7.5 to establish three-dimensional solid model of centrifugal pump, the use of numerical simulation_software FLUENT to conduct numerical calculation, accepted the following conclusions:1. Increasing the radius of curvature of the blade(airfoil) inlet section thickness profile can achieve the purpose of reduce the blade surface secondary flow, which is consistent with Johnson analyzed.2. With the increase of flowrate, the impeller export of wake region decreases, the jet-wake flow structure weakened; with the decrease of the blade export thickness, the impeller export wake loss reduced, the jet-wake flow structure weakened.3. Different specific speed, different distribution of the impeller expor wake region and the jet-wake loss. ( n_s= 49.9) Low specific speed centrifugal pump, the wake region mainly distribute in the central of outlet channel bias pressure surface side, near the pressure surface side formed a narrow jet-wake flow structure; ( n_s= 97.8, 187.9) Central or high specific speed centrifugal pump, the wake region mainly distribute in the intersection area of blade suction_surface and hub, the whole outlet channel formed a wide range of jet-wake flow structure.4. For ( n_s= 49.9) low specific speed centrifugal pump, variation of blade thickness has less impact on pump head and efficiency, with the thinning of blade export thickness, high efficifecy area migrate to the small flowrate points; For ( n_s= 97.8, 187.9) the high specific speed centrifugal pump, with the thinning of blade export thickness, the pump head reduce, efficiency raise. In a small flowrate range, the blade thickness variation has greater impact of the pump head, in a large flowrate range, blade thickness variation of greater impact on the efficiency of the pump, with the thinning of blade export thickness, the high efficiency zone became wider and migrate to the large flowrate points.5.Thinning the blade export thickness and the distance which the blade outlet to the maximum thickness is 45~55mm, the centrifugal impeller has better overall performance. The overall performance of the program two, five, seven which adopting the above thickness programs are better than the same specific speed of other programs.6. For ( n_s= 97.8) the central specific speed centrifugal pump, the anti-cavitation performance of the program four is the best, the program five second, the program six is the worst. The thickness of the blade inlet profile closer to streamline, the better to the pump anti-cavitation performance, increasing the radius of curvature of the blade inlet section can improve the pump anti-cavitation performance.