Structure Improvement And Performance Study Of Smooth Labyrinth Seal For Supercritical Carbon Dioxide Dye Sprayer

In pursuit of low carbon emission and green development today,supercritical fluid dyeing has the advantages of simple process,waterless,no pollution and low energy consumption compared with traditional dyeing,which is of great significance for green development of printing and dyeing industry.Supercritical CO2 spraying process can achieve continuous dyeing by using non-contact sealing structure and counter-spraying device,which greatly improves dyeing efficiency and reduces the influence of spraying tension on fabric.It also has better dyeing uniformity for single layer fabric and has very high research value.In supercritical CO2 sprayer,to ensure the dyeing effect,the pressure in the spray area needs to be maintained,while the sealing performance of non-contact seal is very important to maintain the pressure in the spray area,and becomes one of the key technologies in equipment manufacturing.Therefore,it is very important to study the structure of non-contact seal and improve its sealing performance for industrialized application of Dyer equipment.First of all,this paper introduced the development of supercritical CO2 dyeing process and equipment,pointed out the shortcomings of existing equipment and technology,and introduced supercritical CO2 spray dyeing equipment and non-contact sealing solution at the end of equipment.The leakage measurement experiments of smooth labyrinth seal were carried out and the leakage values of smooth labyrinth seal under different inlet pressures were obtained.The numerical simulation scheme was designed,including the establishment of two sealing geometry models,experimental assumptions,turbulence model,etc.,and grid independent verification was carried out.The leakage simulation experiment of the traditional smooth labyrinth seal was carried out to calculate the leakage,and the leakage data obtained from the simulation was compared with the experimental data to verify the correctness of the simulation scheme.Inspired by the unidirectional structure of Tesla Valve,the author designed a new Tesla valve-like smooth labyrinth seal structure based on smooth labyrinth seal,initially determined the structure size,and established the geometric structure model of Tesla valve-like smooth labyrinth seal.It is verified by numerical simulation that the leakage of Tesla valve-like smooth labyrinth seal less than that of smooth labyrinth seal under the same conditions.The sealing mechanism of Tesla valve-like smooth labyrinth seal was analyzed and the Tesla valve-like smooth labyrinth seal was divided into throttle expansion zone and hedging zone.By changing the inlet angle,channel width,inlet width ratio and arc tangent position parameters of Tesla valve-like smooth labyrinth seal,the leakage was simulated and calculated respectively,and the geometrical structure of hedging zone with less leakage was determined.Then the width of throttle expansion zone with less leakage is found by changing the width of throttle expansion zone.Finally,the optimum structure of hedging zone and throttle expansion zone are combined to form a Tesla valve-like smooth labyrinth seal.Design and manufacture the sealing groove according to the optimized Tesla valve-like smooth labyrinth seal structure,and carry out the leakage test of Tesla valve-like smooth labyrinth seal using plate supercritical CO2 sprayer.It is verified by experiment that Tesla valve-like smooth labyrinth seal structure is better than smooth labyrinth seal,and the influence of different spraying conditions on seal leakage is obtained,which provides a reference for the next industrialization application of supercritical CO2 sprayer.