| The oscillating rotating jet nozzle is connected by a self-excited oscillating cavity in series with a guide rotating cavity,which makes the fluid have the characteristics of oscillating jet as well as rotating jet.Therefore,the nozzle not only overcomes the shortcomings of easy wear and tear of the physical guide parts of the conventional guide rotary jet nozzle,but also makes full use of the advantages of oscillating jet and rotating jet in practical engineering applications.The nozzle can effectively save a lot of energy and water resources in subway track and tunnel cleaning,and has the characteristics of green environmental protection.With the continuous improvement and development of oscillating rotating jet nozzle technology,the nozzle will gradually be more widely used in many other fields of industry.Because most of the existing rotating jet nozzles use physical guide elements to generate swirl,according to its practical application in engineering,it is found that the guide elements are easy to wear and tear,and the ability to guide the swirl after wear is reduced rapidly.At the same time,because of the irregularity of the guide elements,it is very difficult to repair.Therefore,it is easy to wear and difficult to repair after wear.According to the shortcomings of the existing rotating jet nozzle,a new type of oscillating rotating jet nozzle is proposed.The nozzle uses compressed gas as a spinning element to generate rotating jet in the nozzle cavity by tangentially introducing compressed air.At the same time,the self-excited oscillation module is added to further improve the performance of the nozzle.The overall structure of the nozzle is mainly composed of an inlet section,a self excited oscillation chamber,a rotating cavity and a contraction cavity.The inlet is responsible for introducing the incoming flow into the oscillator cavity smoothly.After the fluid enters the oscillator cavity,the oscillatory jet will be generated with the fluid without any other excitation energy.At the same time,the rotating cavity is directly connected with the oscillating cavity,and the oscillating jet generated by the oscillating cavity will produce the corresponding rotating jet after being acted by the compressed air introduced tangentially in the cavity.The resulting fluid with oscillatory and rotational characteristics accelerates into the contracting cavity and ejects from the nozzle outlet on the working surface.Based on the theory of fluid rotating flow and the theory of self-excited oscillating jet,the flow law and actual erosion effect of the internal and external flow field of the oscillating rotating jet nozzle are studied by numerical simulation and experiment.Firstly,based on computational fluid dynamics software FLUENT,a large number of numerical analysis of internal flow field of oscillating swirling jet nozzles with different structural parameters are carried out.The flow field characteristics of the oscillating swirling jet nozzle are analyzed.The results show that the oscillating effect can be produced by the new type of oscillating swirling jet nozzle with various structural parameters,among which the cone angle of the contracting cavity is 45 degrees,the structure of the rotating cavity is 45 degrees*4 and the flow field oscillates well in the nozzle with the use of the organ resonator,and the pressure in the cavity is good.Mean value and pressure peak value are 6.1%and 27.7%higher than those of nozzles with shrinking cavity cone angle 45 and rotating cavity structure 45 and no resonant cavity respectively.The oscillating jet in the chamber has a certain influence,of which the 45*4 rotating guide sleeve has a little influence,and the mean pressure in the chamber of the oscillating rotating jet is not completely proportional to the peak pressure.Based on the results of numerical analysis,the structural parameters of the oscillating swirling jet nozzle were further screened,and the flow field and erosion experiments were carried out.The effects of the structure parameters such as the cone angle of the nozzle,the type of the oscillating cavity and the structure of the rotating cavity on the flow field characteristics in the oscillating cavity of the nozzle were studied experimentally.The experimental and simulation data were compared.The results show that the experimental data and the simulation results of the mean pressure and the peak pressure in the flow field of the nozzle are consistent.There is a certain structural parameter which makes the average pressure of the cavity larger and the oscillating effect better.In addition,the impact force of the nozzle was experimentally studied,and the effects of different structural and working parameters on the actual impact pressure of the nozzle were analyzed,and the flow field in the front chamber was compared.The results show that the average impact force of the nozzle is consistent with the average pressure in the chamber,and the peak value of the pressure in the chamber is in agreement with that in the chamber.The results show that the oscillation effect of the nozzle has the same tendency as the oscillation effect of the external flow field.The experiment further verifies that the nozzle with certain structural parameters makes the average impact pressure larger and the oscillation effect of the jet better.The average impact pressure of the nozzle is larger when the target distance is 3 mm.The erosion experiments of the oscillating rotating jet nozzle were carried out,and the effects of the nozzles with the same target distance and different structural parameters on the erosion effect of brick were analyzed.The flow nozzle is 15.6%high,and the optimum size parameters of the nozzle with better erosion effect are the same as those of the numerical analysis of the internal flow field. |
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