Development of the adjustable Laval nozzle design

Abstract

Various equipment, usually heat exchangers, are used to cool gas flows in different technological processes. However, for the operation of heat exchangers, heat removal is necessary. The article suggests using a Laval nozzle, where the gas flow is cooled due to the physical phenomenon in which the gas flow velocity exceeds the speed of sound. However, it is not always possible to adjust the parameters of the gas flow at the nozzle entrance, which reduces the efficiency of the Laval nozzle. In addition, the nozzle efficiency significantly depends on the gas flow rate change in it. A preliminary analysis of existing designs of adjustable nozzles has shown that they are difficult both to manufacture and operate. To adjust the performance parameters of the Laval nozzle, its design with a variable internal hole diameter (critical section) is proposed. Such a nozzle can be made of an elastic material, such as silicone, and placed in a special housing into which a clamping(placing) nut is screwed. When the nut is screwed in, the elastic nozzle is deformed both in the axial and radial directions. With the help of simulation modeling, the geometric parameters of the proposed elastic nozzle were determined when it was deformed in the axial direction by 10 mm. It was established that the inner hole of the elastic nozzle decreases from a diameter of 12 mm to a diameter of 8.54 mm. Also, with the help of simulation modeling, a study of the elastic nozzle was carried out simultaneously with its axial compression by 10 mm and the action of an internal pressure of 1 MPa at the entrance. To carry out laboratory and experimental studies of the proposed nozzle, a mold was developed and manufactured on a 3D printer, with the help of which an elastic nozzle is cast from SKR-788 silicone. Also, a special stand was made for nozzle research. After measuring the silicone nozzle, it was found that its diameter in the critical section without deformation in the axial direction is 11.8 mm, and with a deformation of 10 mm – 8.6 mm.