Prerequisites for the development of hydro-jet technology in designing women’s headgear at hospitality establishments

Selection of the submerged hydro-jet as a tool for shaping volumetric headgear details was substantiated. The experimental device for determining dynamic pressures of the submerged hydro-jet, which consists of the dynamometer, the power source, the contact group, the platform for operation of the submerged hydro-jet, as well as the top platform, was developed. The device operates so that the measurement of pressure of the submerged hydro-jet could be carried out by measuring reaction force, the module of which is equal to pressure module, and the vector is reverse. This happens due to the transfer of action forces from the fluid to the air medium with the help of the two-arm lever. Measurements are carried out at the distance of 1–30 mm between the cut of the jet-forming mouthpiece and the surface of material, treated at maximal pressure of working medium of 150 MPa. We developed a method for determining dynamic pressures of the submerged hydro-jet depending on geometrical parameters of mouthpieces, such as: length of cylindrical and conoidal parts of the mouthpiece, inlet and outlet diameters of the mouthpiece, radius of the mouthpiece, initial section of the submerged hydro-jet with round outlet openings, radius of the jet in the transition section, semi-axes of the elliptic outlet opening of the mouthpiece, initial section of the submerged hydro-jet with elliptical outlet openings, semi-axes of jets in the transition cross-section. The method provides for determining of hydro impact power of the submerged jet depending on cross-section area at a fixed distance from the end of the mouthpiece, which makes it possible to calculate the desired parameters of pressure in the range from 0.01 to 10 MPa. The influence of geometric parameters of conoidal jet-forming mouthpieces with round and elliptical outlet openings on dynamic pressures of submerged hydro-jets, formed by them, was explored. The experimental values of dynamic pressures of hydro-jet were found to be within specific formation effort ranging from 0.02 to 0.12 MPa. In this case, mean value of coefficient of losses is K b =0.66–0.99 when using conoidal mouthpieces with round outlet opening, and K b =0.42–0.99 when using conoidal mouthpieces with an elliptical outlet opening.