Multilevel Simulation of Direct Operated Safety Valve

摘要

Models (of different completeness) of gas-dynamic processes in direct acting safety valves are considered. All the models are based on the control volume method in 3D, axisymmetric or 1D formulation. In 3D simulation, the internal cavity of the valve is divided into two blocks. In each block, a structured difference mesh is constructed. The mesh in the first block is orthogonal. The proposed approach to numerical simulation of non-stationary 3D gas dynamics enables to determine a spatial structure of flow in a safety valve and its quantitative characteristics (pressure, density, velocity, temperature). To determine the spatial structure and calculate the dynamics of quantitative characteristics of the valve, the first (comprehensive) level of simulation must be applied. The axisymmetric formulation of the gas-dynamic problem can be applied at the stage of disc lifting (valve actuation). Assumption of axial symmetry of the flow under the disc is also justified in simulating stationary characteristics of safety valve. It is a good practice to study wave processes in supply and discharge lines using simplified axisymmetric approach, which is comparable with 1D calculation in terms of computational burden.