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Numerical Simulation and Experiment Study of the Noise Radiated by Two Circular Cylinders in Tandem Arrangements

Author: YangNanQi
Tutor: ZhaoLiangJu
School: Chongqing University
Course: Engineering Thermophysics
Keywords: Serial double cylindrical Aerodynamic noise Large Eddy Simulation
CLC: TB53
Type: Master's thesis
Year: 2009
Downloads: 181
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Abstract


Aerodynamic noise problem is caused by the cylinder flow around widely exist in practical engineering problems in the aviation, marine, offshore platforms, wind engineering, alternating vortex shedding causes vertical lift dramatic changes in the flow direction, causing the structure vibration and noise, severe will destroy the structure. Therefore, how to eliminate or try to reduce the vibration and noise caused by the flow around cylinder engineering design must consider. In this regard, scholars have conducted a lot of research work. Relative to the single-cylinder, two circular cylinders in tandem cylindrical coupling effect between makes the flow more complex, and more widespread. Therefore, the study tandem around two cylinders flow caused by aerodynamic noise has important academic significance and practical value. The numerical simulation of flow and radiation noise in the low-speed turbulent flows through serial double cylindrical. Mixed Methods FW-H acoustic analogy analysis used in the calculation of the flow field using large-eddy simulation model for the flow field data obtained by flow-induced noise. Hybrid approach to calculate the area into a sound source region and acoustic radiation zone, in different areas of the application of different control equation able to isolate the calculated length, reducing the amount of computation. Author pitch ratio L / D = 2 (where L is the the two cylindrical center distance, D is the cylinder diameter), the stream velocity of 20m / s were taken tandem double cylindrical the three diameter D = 5mm, D = 10mm, D = 20mm compared simulation, in order to examine the impact of different cylinder diameter of the flow around two cylinders and flow noise. When the pitch ratio L / D = 2, the diameter D = 10 mm when the selected stream velocity 10m / s, 20m / s, 50m / s, compared to computational simulation, in order to examine the effect of the different speeds. When the diameter D = 10mm, the stream velocity of 20m / s, taking four pitch ratio L / D = 1.5, L / D = 2, L / D = 3, L / D = 5, a comparative simulation calculation, in order to examine different pitch than on flow around aerodynamic noise. The study found that the vortex shedding frequency decreases with the increase of the cylinder diameter, flow around radiated noise sound pressure can increase. With increasing stream velocity, the vortex shedding frequency increases, the flow around a radiation sound pressure level increases. Different spacing than the cylindrical vortex shedding have a certain influence, which also affects the radiated noise, there is noise critical spacing ratio; radiated sound field has obvious point. This paper discusses the measures to reduce the flow around two cylinders noise, can reduce the stream velocity, cylinder diameter and to avoid spacing ratio L / D = 3 layout to reduce the flow noise. To further study the flow around two cylinders noise and verify the results of the numerical simulation of the wind tunnel tandem double cylindrical flow around the noise test, the experimental results show that the maximum sound pressure level and numerical simulation results conform well.

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CLC: > Industrial Technology > General industrial technology > Acoustic engineering > Vibration, noise and its control
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