| The gas flows out from the tube or hole at a relatively high speed,and it impinges on and drives the static air to generate severe disturbances,and the radiated noise is called jet noise.In the hot-dip galvanizing workshop of steel pipe plant,the strong noise produced when the steel plate emerges from the zinc pool and blows excess zinc particles through the external blowing ring nozzle seriously affects the normal production and life of the residents around the factory,and the noise pollution affects the working environment of the workers and endangers the physical and mental health.This reduces the production efficiency of workers,and therefore has important academic significance for the mechanism of jet noise generation and noise reduction noise.This article combines the project of "External Blowing Ring Noise Control in a Hot-dip Galvanizing Plant of a Steel Pipe Co.,Ltd.".The main research contents are:Firstly,five different turbulence models were selected and iterated separately to find the optimal Realizable k-? model for numerical simulation of the external blowing loop flow field.The simulations were carried out for two conditions without steel plate and steel plate,respectively,and they were found to have no steel plate.The development of the jet flow field of the outer blowing ring under the working conditions accords with the jet flow mechanism;when the steel plate enters the outer blowing ring flow field under the working condition of the steel plate,the large-velocity vorticity appears on the upper and lower sides of the steel plate and is close to the steel plate wall surface.The speed at the office is greater.Then,the two boundary conditions of velocity and pressure inlet were selected respectively,and the changes with the axial distance under different speeds and pressures were compared.It was found that the greater the initial velocity and pressure selected,the faster the two increase with the axial distance.The simulated sound pressure level of the original model of the outer blowing ring is up to 120dB,which is basically the same as the 117.5dB measured by the sound level meter.The sound pressure level of the original model noise exceeds the national industrial noise standard,and the noise problem needs to be solved urgently.Secondly,the principle of small hole injection noise reduction is adopted,and the outer ring outlet port is changed into a pore-diffusion structure without slots,and the slot shape simulation analysis is changed to obtain the best effect of noise reduction in the semicircle,and the angle of inclination of the mandrel is discussed for radiation noise.The impact of the simulation found that the sound pressure levels of the 30 semi-circular trough angles of 45 degrees are minimum,and the sound pressure levels of 30 semi-circular troughs whose diameters are 1,2,and 3 mm are compared.When the semicircular trough diameter is found to be 1 mm,The radiated noise has the lowest value.Finally,experimental research was conducted on the external conditions of the external blowing ring.The air compressor was connected to the gas storage tank,and various electromagnetic valve flowmeters were connected to the external blowing ring.An experimental test platform was set up for unslotted steel plates and 30 semicircular grooves.(1mm in diameter)and 45° inclining angle are used for noise tests.The error between the experimental and simulation results is small,and the correctness of the numerical simulation is also verified. |
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