Abstract
The research presents a new analytical grid generation methodology for computational fluid dynamics studies in positive displacement sliding vane rotary machines based on the user defined nodal displacement approach. This method is more inclusive than state of the art ones since it enables the investigation of a broader range of design configurations, such as single, double and multiple-acting vane machines with non-circular housing, slanted blade and asymmetric blade tip profiles. Node number and radial divisions of blade tip are the parameters that affect most the mesh quality. The method was validated against indicated pressure measurements on a rotary vane expander resulting in a confidence interval within 4.31%. The benchmark analysis showed that the proposed method is as accurate as the manual ANSYS ICEM one but more than 1500 times faster (111s instead of 48h to generate 360 grids). The paper further proposes a novel method to track the leakage flows at the blade tip gaps of vane machines through a post-processing routine in ANSYS CFD-Post based on rotating monitoring planes. The leakage assessment on the vane expander case study showed that a 10 μm gap between blade tip and the 76 mm stator led to a 0.06 unit increase of the expander filling factor.
Highlights
Among the positive displacement machines, rotary vane ones benefit from simple geometry, low manufacturing complexity, compactness and competitive performance [1]
Vane machines are currently employed in a broad range of industrial applications, such as refrigeration [2,3], compressed air [4,5], heat to power based on Organic Rankine Cycles (ORC) [6,7], desalination [8,9], automatic transmissions [10,11], as well as oil & gas [12]
To overcome all the shortcomings encountered in the above state-ofthe-art research, this paper proposes a general grid generation meth odology for rotary vane machines that is fully analytical and applicable to a broader range of rotary vane machine configurations such as multiple-acting chambers, non-circular stator, offset blade, asymmetric blade tip profile
Summary
Among the positive displacement machines, rotary vane ones benefit from simple geometry, low manufacturing complexity, compactness and competitive performance [1]. The most common grid generation methods based on the finite volume method to calculate the partial differential equations are spring smoothing, diffusion smoothing, layering, re-meshing and User Defined Nodal Displacement (UDND) [26] Among these approaches, UDND methodology can be used to generate a series of node coordinates representing the rotor mesh at each time step externally, prior to the numerical flow solution. The UDND grid gener ation approach relies on algebraic algorithms with transfinite interpo lation, post orthogonalisation and smoothing for internal nodes distribution This method was experimentally validated against indi cating pressure data on a rotary vane expander for ORC heat to power conversion applications [33]. The validated simulation results showed that supercharging the expanders could increase the specific power output up to 2.4 times since overexpansion of the working fluid was avoided This deforming grid generation methodology is only available for single-acting vane machines with circular stator profiles and blade centred configurations. The numerical re sults with analytical rotor mesh were compared to those with ICEM and differential rotor mesh
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
