Abstract:Current research on the stability of tubular pumps is mainly concerned with the transient hydrodynamic characteristics. However, the structural response under the influence of fluid-structure interaction hasn't been taken fully into consideration. The instability of the structure can cause vibration and cracks, which may threaten the safety of the unit. We used bidirectional fluid-structure interaction to comprehensively analyze the dynamic stress characteristics of the impeller blades of the shaft extension t… Show more
“…The trend of those two curves was consistent, which verifies the accuracy of the numerical simulation. 29 Figure 8.External characteristic diagram of axial-flow pump.…”
Section: Methods Of Numerical Simulationmentioning
In order to study the stability of power generation in reverse of a pumping station unit, the computational fluid dynamics simulation and finite element analysis of the whole passage has been carried out, to study the pressure pulsation and stress distribution law under the condition of power generation in reverse, and compared with them in pump mode. The simulation results showed that, under the condition of power generation in reverse, the pressure pulsation of each monitoring point in front and at back of the runner were higher than that under pump mode. The most amplitude of pressure pulsation was about twice as large as the pump mode, increased gradually from hub to rim. The flow was seriously affected by the rotating runner. The internal frequency of pressure pulsation was blade frequency. The results of fluid–solid coupling showed that the stress mainly concentrated on the root of the pressure side and the suction side of the blade, and the maximum equal stress appeared on the suction side of the blade. The maximum stress and strain value under the condition of power generation in reverse were 20% higher than that under pump mode, and the maximum stress was about twice.
“…The trend of those two curves was consistent, which verifies the accuracy of the numerical simulation. 29 Figure 8.External characteristic diagram of axial-flow pump.…”
Section: Methods Of Numerical Simulationmentioning
In order to study the stability of power generation in reverse of a pumping station unit, the computational fluid dynamics simulation and finite element analysis of the whole passage has been carried out, to study the pressure pulsation and stress distribution law under the condition of power generation in reverse, and compared with them in pump mode. The simulation results showed that, under the condition of power generation in reverse, the pressure pulsation of each monitoring point in front and at back of the runner were higher than that under pump mode. The most amplitude of pressure pulsation was about twice as large as the pump mode, increased gradually from hub to rim. The flow was seriously affected by the rotating runner. The internal frequency of pressure pulsation was blade frequency. The results of fluid–solid coupling showed that the stress mainly concentrated on the root of the pressure side and the suction side of the blade, and the maximum equal stress appeared on the suction side of the blade. The maximum stress and strain value under the condition of power generation in reverse were 20% higher than that under pump mode, and the maximum stress was about twice.
“…In addition, several studies focused on improving and optimizing the pump performance for different pumps such as reactor coolant pumps, multiphase pumps, centrifugal pumps and pulp pumps, by using the orthogonal optimization method. [22][23][24][25] However, there were many researches [26][27][28] in addition to the above researches about tubular pumps, previous studies focused mainly on traditional tubular pumps with an operating head less than 5 m, and only a few studies regarding the performance of tubular pumps with an operating head more than 5 m have been reported. With the extensive construction of long-distance water transfer projects, new challenging requirements for tubular pumps are being proposed, such as high operating head, high efficiency and low shaft power.…”
Section: Introductionmentioning
confidence: 99%
“…However, there were many researches 26–28 in addition to the above researches about tubular pumps, previous studies focused mainly on traditional tubular pumps with an operating head less than 5 m, and only a few studies regarding the performance of tubular pumps with an operating head more than 5 m have been reported. With the extensive construction of long-distance water transfer projects, new challenging requirements for tubular pumps are being proposed, such as high operating head, high efficiency and low shaft power.…”
Tubular pumps are widely used in irrigation and water conveyance projects. However, the operating head of most of these pumps is low, and only a few studies have focused on the design of an efficient tubular pump with a head more than 5 m, which is common in long-distance water supply projects. This work aims to improve the operating head and efficiency of tubular pumps while maintaining a low shaft power. The multi-objective orthogonal optimization method was used to determine the critical parameters of the tubular pump, i.e., blade number, airfoil, blade thickness and guide vane distance, and nine design schemes were selected. Next, by using computational fluid dynamics (CFD), a 3D model of the tubular pumps under different schemes was established, and the results were compared. Subsequently, the range method and weighted matrix method were utilized to find the optimized scheme. In addition, an experimental investigation was performed to verify the simulation and the performance of the designed tubular pump. The results indicated that the optimized scheme improved the operating head to 6.9 m with higher efficiency of 84.2% and a lower shaft power of 27.7 kW. The modeling results were in agreement with the experimental measurements, and the designed tubular pump had a wide range of high-efficiency zones.
“…The time step and the total time obtained by finite element analysis are consistent with those of actual flow fields. Boundary conditions of the impeller blade model involve structural constraints and loads [25][26][27]30,32,33]. Finite element calculation requires enough constraints to constrain the motion of the structure and prevent the rigid body displacement of the structure.…”
Section: Structure Models and Boundary Conditionsmentioning
This paper performed a numerical study into the dynamic stress improvement of an axial-flow pump and validated the simulation results with a prototype test. To further analyze the dynamic stress characteristics of impeller blades of axial-flow pumps, a bidirectional fluid–structure interaction (FSI) was applied to numerical simulations of the unsteady three-dimensional (3-D) flow field of the whole flow system of an axial-flow pump, and the gravity effect was also taken into account. In addition, real-structure-based single-blade finite element model was established. By using the finite element method, a calculation of the blade’s dynamic characteristics was conducted, and its dynamic stress distribution was determined based on the fourth strength theory. The numerical results were consistent with the prototype tests. In a rotation cycle, the dynamic stress of the blade showed a tendency of first increasing, and then decreasing, where the maximum value appeared in the third quadrant and the minimum appeared in the first quadrant in view of the gravity effect. A method for reducing the stress concentration near the root of impeller blades was presented, which would effectively alleviate the possibility of cracking in the unreliable region of blades. Simultaneously, an experimental method for the underwater measurement of the dynamic stress of prototypical hydraulic machinery was put forward, which could realize the underwater sealing of data acquisition instruments on rotating machinery and the offline collection of measured data, finally effectively measuring the stress of underwater moving objects.
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