Optimal Analysis On Preloading Filling Scroll Case Structure Of Large Hydropower Stations

Recent years, with the construction of the large capacity and high head general hydropower station and pumped storage power station in our country, there are more and more preloading filling scroll case structure in applications. The preloading filling scroll case structure is extremely complicated, how to establish its reasonable finite element model, simulate really all courses of its running, and carry out effective finite element analysis, still is an unsolved problem up to now. Selecting reasonable preloading water head to make steel liner and reinforced concrete exerting function satisfactorily is a question which worth more studying. In theory, the preloading filling scroll case structure is segment combined bearing structure, the steel liner can design according to distributed load, and the load still can adjust according to preloading water head. This can reduce the thickness of the steel liner, relax the difficulty of its fabrication and installation, and make steel liner and reinforced concrete exerting function satisfactorily. However, the design of the steel liner of preloading filling scroll case structure is still according to bearing all loads separately at present, its thickness is not reduced yet for the combined bearing structure. In this paper, based on the study status and existent main problem of preloading filling scroll case structure, the author carried out embedded analysis and study on emulating calculation of preloading filling scroll case structure, selecting preloading water head reasonably, optimizing steel liner thickness, and obtained following results:(1) Based on Longtan hydropower station, adopting preloading filling scroll case structure, applying ANSYS program, we established whole 3D finite element model of the emulating method for the stress analysis of the preloading filling scroll case structure, gained the stress distributed disciplinarian and displacements, and proposed the quantity of reinforcing steel in surrounding reinforced concrete. Moreover, we validated the reliability and practicability of the emulating method through comparing emulating method results with tradition method results.(2) Based on the scroll case of Longtan hydropower station, applying the emulating method for the stress analysis of the preloading filling scroll case structure, we carried out the 3D finite element analysis with different preloading water head, studied the relation between the stress distributed disciplinarian of steel liner and reinforced concrete and the preloading water head, at last presented reasonable preloading water head.(3) For the sake of making steel liner and reinforced concrete exerting function satisfactorily of the preloading filling scroll case structure, we optimized the thickness of steel liner of scroll case through theory analysis and actual stress calculation. The study results indicated that the thickness of the scroll case of Longtan hydropower station can reduce from 50～63mm to 42～55mm. After that, their intensities can exert satisfactorily, meet require of the structure security, and bring remarkable economic and social benefit.