Experimental and Numerical Analysis on Flow Characteristics in a Double Helix Screw Pump

Abstract

Experimental overall performances on a double helix screw pump are presented and discussed, focusing on the leakage flow for two different rotational speeds. A comparison between experimental and URANS CFD approaches is performed in order to check the CFD closure models’ validity. Some specific local flow characteristics are extracted from the numerical results which give explanations about leakage backflows inside the screws and local distortion at the pump inlet section.

Numerical Modelling and Experimental Validation of Twin-Screw Pumps Based on Computational Fluid Dynamics using SCORG®and SIMERICS MP+®

“…7 is reported the volumetric efficiency (𝜂𝜂 𝑣𝑣 ) with respect to the discharge pressure. Note that it is reported only for the simulation since the comparison with the measured one is of limited use as reported by [4]: the theoretical volume can only be evaluated by the CAD model and is therefore the same for experiment and simulation as highlighted by equations ( 1), ( 2 Where 𝑄𝑄 𝑏𝑏𝑒𝑒𝑒𝑒𝑏𝑏𝑓𝑓𝑒𝑒𝑒𝑒𝑏𝑏 represents the total mass backflow rate, as discussed in [23], 𝑉𝑉 𝑡𝑡ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑡𝑡𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 is the chamber volume displaced per revolution, 𝑃𝑃 is the pitch and 𝐴𝐴 𝑓𝑓𝑒𝑒𝑓𝑓𝑒𝑒𝑓𝑓 stands for the wetted cross-sectional area of the fluid domain inside the casing and can readily be evaluated by the CAD data. Multiplication by 2 is due to double-started thread spindles.…”

“…Hai-Tao YU1 [21] and Di Zhang et al [22] focused on the research and development of the twin-screw pumps, including a screw rotor profile design, the hydraulic characteristics of the twin-screw pump and the effects of the speed and the screw clearance on the performance of the pump based on CFD using Pumplinx ® and SCORG ® as mesh generator. Zhang et al [23] compared experimental data and URANS CFD results to check the CFD closure models' validity focusing on leakage flow for two different velocities. The results are even compared to an analytical model.…”

Experimental investigations and 3D simulations by the overset grid method on twin-screw machines in both pump and turbine mode

“…Regarding 3D CFD simulations, there have been few studies on twin-screw pumps which are based on either steady simulations e.g., [3,4] or fully unsteady simulations by considering the rotation of screw spindles e.g., [5,6,7,8,9]. In [3,4] by defining the moving wall boundary condition to the static spindle grid, the movement of spindles and therefore the gap kinematics have been simplified which could lead to an inaccuracy of the gap flow assessment and the pump/turbine performance estimation.…”

“…By using deforming mesh methods, the local grid refinement in critical regions, i.e., gaps, is difficult, since due to the significant deviation of gap width and chamber volume, strong grid distortion may occur. Zhang et al [8] have performed unsteady simulations by means of an immersed boundary approach on a double helix screw pump. Although with this method the mentioned drawbacks of deforming mesh method are eliminated, the exact shape of spindles cannot be achieved and is only approximated.…”

Numerical Study of Customised Mesh for Twin Screw Vacuum Pumps

“…Since the grid is generated in the transverse plane the cells become highly nonorthogonal which leads to the numerical error when calculating fluxes through boundaries. According to the CFD study of twin-screw machines [17,18], the main fluid direction is perpendicular to the helix line especially in the clearance area. In addition, the numerical mesh in clearances is not aligned to the main direction of the leakage flow which causes numerical diffusion in clearances.…”