Abstract:The performance of fluid pumps based on Wankel-type geometry, taking the shape of a double-lobed limaçon, is characterized. To the authors' knowledge, this is the first time such an attempt has been made. To this end, numerous simulations for three different pump sizes were carried out and the results were understood in terms of the usual scaling coefficients. The results show that such pumps operate as low efficiency (<30%) valveless positive displacements pumps, with pump flow-rate noticeably falling at the … Show more
“…For this study, all the simulations were carried out in ANSYS CFX v 15, which is a commercially available computational fluid dynamics (CFD) code. Details of the simulation setup, including the method for modelling the motion of solids immersed in a fluid flow field and calibration against experimental data can be found in [15] and are not repeated here.…”
Section: Methodsmentioning
confidence: 99%
“…Previously, the gross performance of Wankel pumps has been characterized by Wan et al [15] in terms of pump scaling coefficients; and, in essence, it was demonstrated that it operates as a low efficiency (<30%), valveless positive displacement pump. It was also found that internal flow field is rich in 3D vortices.…”
In the present study, particle track simulations of inert particles belonging to two species (binary mixing), carried out using a commercially available CFD code indicate that pumps based on Wankel type geometries (Wankel pumps) are capable of functioning as mixers, as well as pumps; and hence such devices could also drive a semi-batch micro-reactor system. The numerical results reveal that mixing quality improves as the particles loop through the pump cavity and then saturates after a time, and that mixing rate increases with rotor speed. Examination of the structure of the flow-field suggests that the underlying mechanism of mixing is a combination of the stretching (resulting in particle dispersion) and folding of streamlines into Taylor-like vortex pairs, accounting for the vertical symmetry in the particle distributions. Differences in the flow structure, detected by plots of fluid velocity components, could account for differences in particle distributions generated for various rotor speeds.
“…For this study, all the simulations were carried out in ANSYS CFX v 15, which is a commercially available computational fluid dynamics (CFD) code. Details of the simulation setup, including the method for modelling the motion of solids immersed in a fluid flow field and calibration against experimental data can be found in [15] and are not repeated here.…”
Section: Methodsmentioning
confidence: 99%
“…Previously, the gross performance of Wankel pumps has been characterized by Wan et al [15] in terms of pump scaling coefficients; and, in essence, it was demonstrated that it operates as a low efficiency (<30%), valveless positive displacement pump. It was also found that internal flow field is rich in 3D vortices.…”
In the present study, particle track simulations of inert particles belonging to two species (binary mixing), carried out using a commercially available CFD code indicate that pumps based on Wankel type geometries (Wankel pumps) are capable of functioning as mixers, as well as pumps; and hence such devices could also drive a semi-batch micro-reactor system. The numerical results reveal that mixing quality improves as the particles loop through the pump cavity and then saturates after a time, and that mixing rate increases with rotor speed. Examination of the structure of the flow-field suggests that the underlying mechanism of mixing is a combination of the stretching (resulting in particle dispersion) and folding of streamlines into Taylor-like vortex pairs, accounting for the vertical symmetry in the particle distributions. Differences in the flow structure, detected by plots of fluid velocity components, could account for differences in particle distributions generated for various rotor speeds.
“…In other instances, external energy or force is applied to perturb the sample species to encourage mixing through diffusion. A review of microfluidics mixing is given by Lee et al 1 Wan et al 2 had been investigating the use of Wankel-like pump in microfluidics applications. They found from CFD simulations that a 2-apex rotor turning at low speed in 1-lobe epitrochoid-shaped housing is able to generate vortices at low Reynolds number and hence has the potential to improve mixing.…”
Section: Background: the Microfluidics Mixermentioning
This paper discusses a case study of a process that provides a holistic design experience by integrating two independent project modules of an undergraduate degree programme. The project proposed by an external party involves the design, manufacture and testing of a scaled prototype for microfluidics applications. The systematic and integrated approach described in the same format as the students' project report resulted in a novel gearless Wankel-like pump that provided visual results that compare well with the external party's numerical studies.
“…Here the student was introduced to a mathematical model that describes the perimeter (i.e. the trajectory of the rotor tips, Figure 1) of the Wankel-type geometry, which is known as an epitrochoid 6 Figure 1.The epitrochoid trajectory of the ( m = 2) two-apex rotor tip. (a) Nomenclature for the m = 2 epitrochoid parametric equations.…”
Section: Basic Conceptsmentioning
confidence: 99%
“…(b) Locating the 'centre' of the m ¼ 2 Wankel geometry. (c) and (d) Illustrate snapshots of the displacement of the rotor centre relative to the 'centre' of the Wankel geometry and the linear 'sliding action' of the centre point along the slot (in the rotor) as the rotor rotates.an epitrochoid6…”
A two-stage Wankel pump/mixer device has been designed and prototyped as part of a final-year undergraduate project. Based on the concept of the Wankel rotary engine, the device features a 'two-apex' rotor instead of the conventional 'three-apex' rotor. The novelty of the device addresses a unique axis of rotation for the rotor, driven by a crankshaft. In particular, in order for the motion of the rotor to exhibit a trajectory to consistency with an epitrochoid, the rotational motion is guided by the linear motion of a pin sliding along a groove within the rotor; this novel linear-to-rotational motion approach is known as the Lau-Wan design. The feasibility of the Lau-Wan design has been demonstrated in an earlier project. Here, the prototype comprises two Lau-Wan pump/mixers serially connected to form a two-stage system-the aim is to study the effectiveness of the mixing of fluids as the fluids flow from one stage to the other when both rotors are rotating 'in phase'. A simple drive system was implemented by (a) coupling the two crankshafts using a timing belt and (b) coupling a low-speed motor to one of the two stages using a timing belt. Experiment was conducted to analyze the flow pattern of liquids in both stages using two types of liquid with different colors (and a slight variation in the viscosity). The flow pattern within the chamber of the first stage shows somewhat similar mixing patterns to those predicted by computational fluid models. We note that (1) the extent of drawing the fluid into the chamber, followed by compressing the fluid, depends on the rotor position, (2) laminar flow dominates the flow pattern during the suction and compressive actions of the rotor but microturbulence occurs in the regions adjacent to the rotor, (3) when the rotor rotates, the number of laminar layers somewhat increases with time. On the other hand, the second stage appears to be very efficient at drawing one of the two fluids; this may be
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
