Study of the flow characteristics of a shut-off and control device for generating a controlled gas flow

Introduction. Industrial pipeline valves are among the most important elements of energy metering, both within common gas distribution systems and as a precision control element directly acting on an actuator or mechanism. The most specific requirements apply to shut-off and control devices (SCDs) used in high-risk industries, as well as in precision high-tech critical manufacturing. The ability to change and regulate the flow characteristic, as well as the response time of the element separating the two parts of the communicating system, play a significant role. The use of SCDs to shape an inert gas flow, according to the established law, is a key requirement for actuators in systems for manufacturing parts (the material of which is, as a rule, in a nanostructured state) using superplastic forming (SPF). The requirements for the actuator of a gas distribution system to perform the SPF operation are determined by a graph based on the part geometry. A bellows shut-off needle valve is adopted as the actuator unit, as it is optimal in design due to the seal used, as well as a metering needle that allows changing the flow cross-section of the channel. Methods and Materials. Modeling and finite element (FE) analysis to determine the flow characteristics of a bellows shut-off needle valve in a gas distribution system were performed using a specialized software package for scenarios of control rod handle rotation at 10°, 45°, and 90°, taking into account the required boundary conditions. Full-scale tests to verify the finite element method (FEM) calculations were carried out on a test bench using a bellows shut-off needle valve with the required parameters of the test bench elements. Results and Discussion. The article presents the results of finite element analysis (FE) and full-scale bench tests to verify the modeling results. The research revealed that the dependence of the working fluid flow rate on the angle of rotation of the control rod handle is not linear. In the range of handle rotation angles from 0° to 40°, a stable increase in flow rate is observed. With a further increase in the handle opening angle from 40° to 60°, the nature of the change in the working fluid flow rate changes. Abrupt changes are observed, which can be explained by a relatively large opening of the housing seat. This leads to phenomena (stalls, flow swirls, etc.), causing flow rate fluctuations. After reaching a rotation angle of 60°, the flow rate graph becomes oscillatory. In this section, the flow is constantly exposed to significant turbulent phenomena and becomes unstable, which complicates the accurate determination of the working fluid flow rate. Conclusion. A combination of finite element modeling and a full-scale experiment allowed us to verify the flow characteristic obtained through FEM calculations in a specialized software package with data from full-scale bench tests of a bellows-sealed shut-off needle valve. The discrepancy between the FE analysis results and those obtained during full-scale tests is within 5%, allowing the method described in this article to be used to obtain sufficiently accurate and reliable results.