Abstract
The bulb tubular unit has advantages over other units in the low head, large discharge, and tidal energy. The development and utilization of low head and ultralow head hydraulic resources can increase the runner’s energy parameters, make up for the defects of large size and low speed of the unit, and reduce the construction investment. The bulb tubular turbine’s operation stability and structural strength are compared and analyzed by the orthogonal test method to improve the perfomance of bulb tubular turbine. The results show that the optimal design scheme can be obtained when the number of guide vane is 16, the distance between the guide vane and the blade is 1995 mm, the hub ratio is 0.31, the relative twist angle of the blade is 27°, and the cascade density is 0.72. After optimization, the bulb tubular turbine’s efficiency and output are increased by 5.72% and 2.86% at a low flow rate, respectively. The vortex at the tailpipe is reduced, and the blade work effect and the cavitation performance are well. The maximum pressure pulsation amplitude in the flow passage is reduced by 73.15%, the maximum blade deformation is reduced by 39.59%, and the maximum blade static stress is reduced by 13.16%. Finally, the reliability of numerical simulation results is verified by the model test.
Highlights
Tubular turbines have been widely used and developed rapidly due to their excellent technical and economic characteristics and applicability since they came out in the 1930s
E time-domain information of pressure pulsation is obtained through unsteady calculation, and the frequency domain characteristics are obtained through Fourier transform. e maximum static stress and maximum deformation of the runner blade under various design schemes are obtained through the unidirectional fluid-solid coupling calculation
(2) Range analysis shows that blade relative torsion angle is an important geometric parameter in the hydraulic design of bulb tubular turbine. e number of guide vanes mainly affects the unit output; the distance between guide vane and blade mainly affects efficiency; hub ratio mainly affects pressure pulsation and blade deformation; cascade density mainly affects blade static stress. e relative twist angle change of the blade has the most significant influence on the four test evaluation indexes except the blade’s static stress
Summary
Tubular turbines have been widely used and developed rapidly due to their excellent technical and economic characteristics and applicability since they came out in the 1930s. With the increase in the operation of bulb tubular turbine units, the problem of failure is gradually exposed by the unit’s operation [2, 3] It wastes hydraulic resources and reduces the unit’s operating efficiency, resulting in the reduction of economic benefits, and there are great safety hazards in the operation of the unit [4]. The guide vane and runner section’s design parameters will affect the structural strength of the flow passage components, the hydraulic performance, and the stability of the unit [5]. Wang et al [10] obtained the influence law of the tubular turbine runner cascade density on the turbine’s hydraulic efficiency through theoretical analysis and experimental research. Ey found that the hydraulic loss of the guide vane section and runner section accounted for a large proportion, which provides reference opinions for the bulb tubular turbine’s optimization design. An orthogonal table L16 (45) with five factors and four levels is selected to optimize the turbine’s design [23]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
