Nozzles hydropneumatic

For creating a continuous jet we used a conical-cylindrical nozzle 8 mm in diameter for a drop-type jet we used hydropneumatic and ejector nozzles " The size of the drops was determined by trapping them with a sticky compoimd. (The median diameter of the drops obtained after emerging from the hydropneumatic nozzle was 275 M.) The specific pressure over the cross section of the jet was measured by means of a system of detectors and an MPO-2 oscillograph. 

Below we present the values of and Kj for cleaning an oil-free surface with jets of drop structure generated by a hydropneumatic nozzle (distance to painted plates, 1 m water pressure, 2.5 kg/cm air pressure, 1 kg/cm ) ... 

The water was converted into drops in the hydropneumatic nozzle by means of compressed air. 

We see from the results presented that a hydropneumatic nozzle producing a drop-tjrpe jet cleans the surface almost completely for a water pressure of 2,5 kg/cm in front of the nozzle with an air pressure of 1 kg/cm the ejector nozzle does likewise for an initial air pressure of 4.5 kg/cm. In this the average specific pressure of the drop-type jet was 0.002-0.006 kg/cm, i.e., 1-2 orders lower than in the case of the continuous jet, while the water consumption was 10 liters/m of the treated surface for the hydropneumatic and 3.5 liters/m for the ejector nozzle. 

The degree of cleaning the surface depends not only on the water consumption but also on the angle at which the jet meets the surface under treatment. Below we present some data relating to the efficiency of removing particles with a hydropneumatic nozzle as a function of the angle of incidence on the painted surface (water flow, 4 liters/m ) ... 

In jets of drop structure obtained by means of hydropneumatic and ejector nozzles, a large number of drops of diameter no greater than 500 m is formed these interact with others in the jet and on striking the surface. In order to determine the efficiency of the cleaning process as a function of drop composition we therefore studied the detachment of particles secured by the free settling of single drops this made it possible to eliminate the influence of secondary processes associated with the interaction of the drops between themselves. 

The velocities of the jets emerging from hydropneumatic and conical—cylindrical nozzles greatly exceed those required for the transportation of the particles, and this ensures the removal of the particles from the zone of contact between the jet and the surface after being detached. 

For a jet formed by a hydropneumatic nozzle the efficiency exceeds that of a continuous jet both in the detachment of the particles and in removing them from the contact zone. 

It should be noted that the experimental results presented here were obtained for particles spherical in shape. In practical conditions the shape of the particles will differ from spherical however, this does not introduce any sharp change into the efficiency of particle removal. Thus, the value of in treating a painted surface with a jet from a hydropneumatic nozzle with a water flow of 4 liters/m is 910 for spherical particles, and 630 for particles... 

It is hard to free an oily surface from contaminations, since the adhesion of the particles is much stronger (see 14). For example, in treating an oily surface with a drop-type jet (hydropneumatic nozzle) half the adhering particles are removed (yp = 53%), while on using the same jet on an oil-free surface nearly all the particles disappear. In order to ensure the complete cleaning of oily surfaces the velocity of the drop (100-300 M in size) should be 60-80 m/sec for oil-free surfaces 1 m/sec or less is sufficient. 

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