Gonzalez, I.; Naseri, A.; Rigola, J.; Perez, C.; Oliva, A. International Conference on Compressors and their Systems p. 012032-1-012032-10 DOI: 10.1088/1757-899X/232/1/012032 Data de presentació: 2017-09-11 Presentació treball a congrés
Suction and discharge processes with self actuated valves have a major influence in efficiency and reliability of hermetic reciprocating compressors. Understanding the operation completely in order to enhance compressor's design needs precise prediction of the fluid-structure interaction complexities involved in these processes. This paper presents a comprehensive description of a numerical methodology to account for the coupled behaviour of a reed valve and a turbulent flow. The method is based on a partitioned semi-implicit scheme that only strongly couples the fluid pressure term to the structural solver. A three-dimensional CFD analysis with LES turbulence modelling is used for the flow while a combination of plate theory and mode summation method is used for the solid. The dynamically changing domains are tackled by means of lagrangian and arbitrary lagrangian-eulerian approaches for the solid and the fluid, respectively. The whole model is compared with experimental data at Reynolds number 10, 000, showing good agreement in lift amplitude and deformation fluctuations. Finally, as an illustrative case, results regarding lift, pressures, force and effective areas are compared with those of a valve with wider gland.
This paper presents a complete numerical procedure to study the fluid-structure interaction problem of incompressible flow through reed valves, typically employed in hermetic reciprocating compressors. A partitioned semi-implicit coupling scheme is implemented, which only strongly couples the added-mass-effect (pressure term) of the fluid to the structure hence, assuring numerical stability and avoiding excessive computational cost. The fluid is solved by a three-dimensional CFD solver using large eddy simulation closures to model the turbulent flow, while the reed valve is described with the classical plate theory and the normal mode summation method. To showcase the potentiality of the proposed methodology, a sensitivity analysis regarding valve thickness is carried out for a given velocity in the feeding channel. Considerable differences, mainly in valve lift and pressure drop, are appreciated between the considered configurations.
This paper represents numerical simulation of fluid-structure interaction (FSI) system involving an
incompressible viscous fluid and a lightweight elastic structure. We follow a semi-implicit approach in which we
implicitly couple the added-mass term (pressure stress) of the fluid to the structure, while other terms are coupled
explicitly. This significantly reduces the computational cost of the simulations while showing adequate stability.
Several coupling schemes are tested including fixed-point method with different static and dynamic relaxation,
as well as Newton-Krylov method with approximated Jacobian. Numerical tests are conducted in the context of a
biomechanical problem. Results indicate that the Newton-Krylov solver outperforms fixed point ones while introducing
more complexity to the problem due to the evaluation of the Jacobian. Fixed-point solver with Aitken's relaxation
method also proved to be a simple, yet efficient method for FSI simulations.
This article is published under a CC BY licence. The Version of Record is available online at: http://dx.doi.org/10.1088/1742-6596/745/3/032020.