Numerical Simulation Of Flow Noise For A Pipeline Pump And Its Outlet Pipe

The pipeline pump has the characteristics of simple structure, small occupation area,convenient installation and maintenance, and so on. It has been widely used in transportation,urban and rural water supply and drainage, as well as oil and chemical industry. A LPP100-390 type pipeline pump produced by a certain enterprise of Zhejiang is chosen as the research object,based on computational fluid mechanics, the Lighthill’s acoustic analogy theory and modal analysis theory, the pipeline pump inner flow and outlet pipe acoustic- solid coupling are calculated and analyzed. The main content includes the following five aspects.1. The simulation software ANSYSCFD is used for numerical simulation of inner flow field of pipeline pump and then the result of which will be compared with the trial value. The coincidence of the two results can prove the veracity and reliability of numerical simulation.Then the distribution of inner pressure of pump will be analyzed.2. Based on the steady numerical simulation, the unsteady numerical simulation is also conducted on pipeline pumps, with extracting the pressure fluctuation inside pump and analyzing corresponding observation point. Then the acoustic software LMS Virtual. Lab is used to study and analyze the distribution of its inner sound field.3. The noise source inside the straight pipe is analyzed and then the structure modal analysis is conducted. The result shows that the low order natural frequency of the straight pipe is close to the frequency of the fluid pressure fluctuation, which may cause resonance.4. The liquid column inside the straight pipe is theoretically calculated, and the natural frequency of its high order acoustic mode is obtained, then corresponding schematic diagrams are drawn. After that, a numerical simulation is made based on LMS Virtual. Lab. The result shows that the theoretical calculation frequency of acoustic modes is approximately equal to simulation frequency and the acoustic mode distributions are also consistent, which indicate the veracity of numerical simulation results. The natural frequency of acoustic modes and the frequency of low excitation do not exist in the range of the frequency of resonant, as a result,resonance may not be considered.5. On the basis of the results of structure mode analysis and acoustic mode analysis, with LMS Virtual. Lab calculating the modes under the condition of structural-acoustic coupling, and analysis of the effect of coupling on structure modes and acoustic modes, it can be concluded that structural-acoustic coupling has little effect on structure modes and acoustic modes and structural-acoustic coupling has effect on both natural frequency and amplitude of modes.This article conducts a numerical simulation on pipeline pumps and the straight pipe by CFX, Workbench and LMS Virtual. Lab, and analyzes the features of the internal flow field of the pipeline pump and the pressure fluctuation in the spiral case, the acoustic propagation characteristics and the structure modes, the acoustic modes, the coupling modes and the propagation characteristic of the outlet pipe, which may provide some reference for the noise reduction of pipeline pump and the straight pipe.