Gap Length Research Articles

Research on the Mechanism of Thermal Power Enhancement in an Interior Permanent Magnet Eddy Current Heater Driven by Wind

This article uses numerical simulation methods to study the comprehensive influences of the stator structure and materials on the thermal power of an interior permanent magnet eddy current heater (IPMECH). By analyzing the air-gap magnetic flux density (MFD), stator MFD, thermal power, and torque at different rotational speeds, the mechanism of thermal power enhancement has been revealed in depth. The results indicate that the armature magnetic field (MF) generated by the eddy current produces a magnetization effect on the side of its rotation direction, but the MF in the stator will be weakened in general, and this effect becomes more significant with the increase in the rotational speed. The stator material of the IPMECH has higher permeability, which has higher thermal power and torque, and a lower proportion of high-order harmonics, which is beneficial for reducing the radial vibration of the IPMECH. A permanent magnet with high remanence can increase the thermal power and torque of the IPMECH. Reducing the length of the air gap is beneficial for improving the thermal power, but it also increases the harmonic MFD. The rotational speed is 200 rpm, the air gap is 0.1 mm and 2 mm, and the thermal power is 1.12 kW and 0.35 kW, respectively. The fundamental amplitudes of the 0.1 mm and 2 mm air-gap lengths are 0.94 T and 0.64 T, respectively, and the 3rd harmonic Bi* values are 0.24 and 0.18, respectively. At rotational speeds of 200 rpm, 800 rpm, and 1600 rpm, the δPmax values are 17 mm, 11 mm, and 8 mm, respectively. When designing a heater, the higher the rotational speed, the smaller the stator wall thickness should be.

Model uncertainty quantification of a degradation model of miter gates using normalizing flow-based likelihood-free inference

Degradation modeling is essential for failure prognostics of miter gates and subsequent risk-informed maintenance or operational decision-making. Typically, degradation models are formulated based on certain assumptions and simplifications and may not fully capture the complexity of underlying degradation mechanisms. Even minor errors in such models may lead to significant discrepancies in failure prognostics due to error accumulation over time. Aiming to improve the accuracy of the degradation model and ensure reliable failure prognostics, this article proposes a degradation model updating framework for miter gates using normalizing flow-based likelihood-free inference, accounting for both model parameter uncertainty and model form uncertainty (i.e., model bias). The proposed work consists of two phases: the offline training phase and the online updating phase. During the offline training phase, the unknown model bias term is modeled as a random noise with uncertain standard deviation. Synthetic data are then generated using a physical model based on prior knowledge of the uncertain model parameters and model bias. The synthetic data are utilized to train an inference model, which has a summary network for data compression and a conditional invertible neural network for parameter estimation. In the online updating phase, the trained inference model uses strain observations to obtain posterior samples. The Gaussian mixture model and dual particle filter techniques are utilized to recursively update posterior samples, thereby improving the estimation accuracy. Subsequently, model bias is inversely estimated using the degradation model, which uses the updated model parameters and the gap length from the inference model. Following that, a regression model is constructed to correct the biases inherent in the simplified degradation model. This process is implemented iteratively over time to perform continuous model updating and failure prognostics. Results of a case study demonstrate the efficacy of the proposed framework in reducing both model parameter uncertainty and recovering model biases and thereby improving the accuracy of failure prognostics of miter gates.

Parametric Optimization For Power Generation Of Flow Induced Vibration Energy Harvester

Flow-induced vibration occurs when the motion of fluids through a structure induces oscillations or vibrations in the structure. An effective flow-induced vibration energy harvester has substantial challenges due to the river's irregular velocity flows. It is not practicable to use one parameter for all velocities. This work presents the testing of a flow-induced vibrational energy harvester in laminar flow using two circular cylinders positioned in tandem within an open-channel flow. A CFD simulation using COMSOL Multiphysics was performed for the proposed parameter. A comprehensive simulation run at multiple Reynolds numbers with varying gap lengths between the bluff bodies is studied to determine the maximum power generated. Simulation results show that the optimal gap lengths for Re 60, 80, 100, 120, 140, and 160 are 8.5, 6.0, 3.0, 3.0, 3.5, and 4.5, respectively. These gap lengths result in power outputs of 0.0315 W, 2.616 W, 1.899 W, 0.6552 W, 0.5018 W, and 0.3782 W. By demonstrating the relationship between Reynolds number and gap length, this study provides important information for maximising the energy harvesting from flow-induced vibration (FIV).

Dynamics of real-time forecasting failure and recovery due to data gaps: A study using EnKF-based assimilation with the Lorenz model

Data assimilation-based real-time forecasting is widely used in meteorological and hydrological applications, where continuous data streams are employed to update forecasts and maintain accuracy. However, the reliability of the data source can be compromised due to sensor and communication failures or physical or cyber-attacks, and the impact of data stream failures on the accuracy of the forecasting system is not well understood. This study aims to systematically investigate the process of data stream failure and recovery for the first time. To achieve this, data gaps with varying lengths and timings are introduced to EnKF-based data assimilation system on the Lorenz model operating in both chaotic and periodic modes. Results show that the forecasting error grows exponentially in the chaotic mode but was limited in the periodic mode from the start of the data gap. For chaotic mode, the recovery of the system depends on the length of the data gap if the model error is not saturated; after saturation, the timing of the data stream recovery is important. Moreover, even long after restarting the data assimilation in the chaotic mode, the forecasting system cannot fully restore the original accuracy, while the periodic mode is generally resilient to disruption. This research introduces new metrics for quantifying system resilience and provides crucial insights into the long-term implications of data gaps, advancing our understanding of forecasting system behavior and reliability.

Design and test of a module of a breathable Electrostatic Shield for the MITICA 1 MV negative ion Beam Source

The electrical insulation of the MITICA Beam Source at 1 MV is a challenging issue, which has not been fully addressed so far on the basis of experimental results and of theoretical models available in literature. Being MITICA the full-size prototype of the Heating Neutral Beam Injector for the ITER fusion experiment, its electrical insulation is constituted just by vacuum gaps and alumina insulators, since other insulating materials such as SF6 gas or fibreglass-reinforced plastic (FRP) would be quickly degraded by the expected neutron flux produced by fusion reaction. Extrapolations based on HV tests on reduced-scale models have recently indicated the risk of electrical breakdowns in the vacuum gap between electrodes nominally operating at -1 MV and the vacuum vessel (at ground potential). The risk of electrical breakdown can be mitigated by introducing an intermediate Electrostatic Shield (ES), which essentially is an equipotential (metallic) enclosure surrounding the HV electrode, so as to divide the vacuum gap in two independent insulating gaps of 400 kV and 600 kV respectively. However, for optimal negative ion production, the ion source shall operate in H2 or D2 at a pressure of ∼ 0.3 Pa and unavoidably produces a flow of gas leaking out in the surrounding vacuum. Thus, the presence of an intermediate shield can substantially increase the background gas pressure in the vacuum gaps, and, due to the large gap length (0.6 m), exacerbate the risk of breakdown when the pressure approaches the conditions of Paschen-type discharges. In addition to this, RF-induced breakdowns were found on the rear side of the ion source during the operation of the prototype source SPIDER, which were somewhat correlated to a relatively high hydrogen pressure in that area. For these reasons, a structure capable of constituting a full equipotential barrier all around the BS and, at the same time, having sufficient gas conductivity (breathability) to allow efficient pumping of background gas, has been designed. In the first part of the paper, the requirements and design optimization of a breathable module of the intermediate ES are described. Then, an experimental campaign for the validation of the electrode implementation the test configurations and the experimental procedure is discussed.

Optimal design and control strategy for enhanced battery thermal management

The Battery Thermal Management System (BTMS) plays a crucial role in the safety and performance of new energy vehicles. This study proposes an innovative cooling structure design that ingeniously combines the advantages of air cooling, water cooling, and Phase Change Materials (PCMs) to enhance the cooling efficiency of the battery system. Through numerical simulations, the effectiveness of this cooling system was validated and further supported by experimental evidence confirming the accuracy of the simulation results. Subsequently, this research utilized the Response Surface Methodology (RSM) to optimize key parameters of the cooling structure, including the fin height, gap length, and PCM thickness, with their optimal values determined to be 5.20 mm, 17.69 mm, and 3.38 mm, respectively. This parameter optimization work provides precise guidance for the design of battery thermal management systems, contributing to enhanced heat dissipation performance. To further enhance the intelligence of battery thermal management, this study introduced a novel neural network model based on Temporal Convolutional Networks (TCN) and Bidirectional Long Short-Term Memory (BiLSTM) with Multi-Head Attention (MHA). This model is capable of predicting temperature changes during the battery discharge process in real-time with high accuracy. Based on the prediction results, this research designed an efficient control strategy that, compared to a scenario without a control strategy, demonstrated a reduction in energy consumption by 20.87 %, a decrease in maximum temperature by 2.52 K, and a reduction in the maximum temperature difference by 0.05 K. These results not only prove the effectiveness of the control strategy but also provide a new direction for the optimization of battery thermal management systems.

On the Energy Cost for Nitrogen Fixation in DC Glow Discharges in Atmospheric‐Pressure Air

ABSTRACTModeling of the production of nitrogen oxide molecules in DC discharges in laminar longitudinal flows of atmospheric‐pressure air is performed. Two‐dimensional nonequilibrium discharge model includes the system of gas dynamic equations and balance equations for various plasma components. Simulations are performed for the discharge currents 50–600 mA and gas flow velocities 1–10 m/s. In considered conditions, the gas temperature in the discharge core varies in the range of 3000–6000 K. Spatial profiles of the densities and fluxes of produced species are obtained, both inside the discharge and in the afterglow region. The energy cost for the production of nitrogen oxides is calculated, depending on the discharge current, gap length, and gas flow velocity. The results of the simulation are compared with available experimental data.

Research on dynamic performance and mechanical model of a novel magnetorheological shear thickening damper with adaptive variable damping gap

Abstract Magnetorheological shear thickening fluid (MRSTF) is an intelligent composite material, which shows considerable potential in semi-active vibration control. However, the current research is mostly limited to the study of the rheological properties of materials, and there is still a lack of damper structures that can effectively utilize the dual-control characteristics of MRSTF. In this paper, a novel damper structure with adaptive adjustable damping gap length is proposed. Its unique design integrates an adaptive internal damping gap that changes with the movement of the piston and an external gap controlled by the magnetic field, providing a relatively wide range of current-controlled damping force and reliable adaptive adjustment capabilities. Based on the M-S shear stress constitutive model and structural characteristics, the mechanical model is derived from the force balance of the micro-element, and verified by performance test and curve fitting. The effectiveness of the new damper structure proposed in this paper is verified by dynamic performance test. The results show that the damper has a wide range of current controlled damping force at low speed and reliable adaptive adjustment capability at high speed. Finally, the accuracy and universality of the modified mechanical model of damper are verified by curve fitting method. All these studies can offer an effective guidance for further application of MRSTF in the field of semi-active vibration control.

Model modification and influence of edge effect on effective area of giant electro-rheological polishing using plate electrodes

Abstract Giant electro-rheological polishing (GPRP) is recognized as an innovative ultra-precision machining technology with significant potential. However, the pronounced edge effect within the GPRP's polishing gap can introduce errors in calculating the effective area and designing the electrode structure. This, in turn, may lead to under-polishing and an increased risk of insulation breakdown. In this study, COMSOL was employed to investigate the electric field distribution characteristics within the polishing gap. This exploration aimed to refine the calculation model of the effective area, optimize the plate electrodes' structure and size, and diminish the likelihood of insulation breakdown. Through systematic finite element simulations, the impact of polishing voltage, inter-electrode gap, and plate length on the edge effect was thoroughly analyzed to ascertain its influence range. The simulation findings revealed that, while maintaining a constant inter-electrode gap for the tool electrode, variations in the polishing gap, polishing voltage, and plate length within specific ranges resulted in an edge effect influence range of approximately 1 mm. Moreover, when the machining gap, polishing voltage, and plate length remained unchanged, the edge effect influence range increased proportionally with the electrode gap within a specific range, approximately equivalent to the size of the electrode gap. Experimental validation of the giant electro-rheological effect confirmed the existence and influence range of the edge effect, aligning with the finite element simulation results. Ultimately, modifications to the calculation model of the effective area were proposed, along with a solution to optimize the electrode size and structure, with the objective of reducing the probability of insulation breakdown. In practical applications, this work can provide a valuable reference for electrode structure design, insulation breakdown improvement and parameter selection.

The flow model of the overlap spool valve considering the transition between laminar and turbulent flow

It remains uncertain whether the flow state at the spool valve is laminar or turbulent under small openings. The annular slit flow and the damping hole flow are proposed to be equated to model the spool valve flow. The mutual transition criterion between laminar and turbulent flows is developed. The results indicate that the flow turns from transitional flow to turbulence as the valve opening increases to 5.2 μm. The flow coefficient increases linearly in transitional flow and remains constant in turbulence. Laminar flow may occur when the annular gap's length exceeds 9.45 μm. The effect of structural parameters including overlap, radial clearance, wear fillet, and temperature on flow transition is discussed. Wear on the valve port counteracts the positive overlap. Flow gain continues to rise, pressure gain increases and then falls, reaching a maximum of 5 × 1012 Pa/m. Valve performance exhibits a brief ramp-up time. The theoretical model and analysis aim to elucidate the flow characteristics and performance evolution of the spool valve.

Influence of different factors on gap breakdown process with hot electrode and high temperature gas medium in low voltage circuit breaker chamber based on particle-in-cell/Monte-Carlo collision simulation

Different factors such as gas composition inside the low voltage circuit breaker (LVCB) chamber and the residual plasma in the post-arc stage affect the breakdown process, which in turn affects the breaking capacity of LVCBs. In this paper, the effects of non-parallel electrode structure, gas temperature and pressure, electrode temperature, and gap distance on gap breakdown of hot electrode under high temperature gas conditions were studied, for which a particle-in-cell/Monte-Carlo collision simulation model has been established, which takes into account the effects of high-temperature gas components, cathode electron thermal emission, electron collision ionization and other effects, and simulation studies have been conducted. The simulation results show that the increase in gap gas temperature, the decrease in air pressure, and the increase in electrode temperature will lead to the gap breakdown more easily. With the increase in the gap length, the breakdown voltage increases, but the average electric field intensity required for breakdown decreases. In the non-parallel electrode structure, the breakdown occurs first at the position with the shortest gap distance, then the cathode sheath forms and extends along the electrode surface to other areas, and finally, the entire gap breaks down.

Decreasing the non-linearity of hybrid reluctance actuators by air gap design

This paper presents an air gap design approach to improve the linearity of rotational Hybrid Reluctance Actuators (HRAs) used in fast steering mirrors. The approach involves modeling a one-degree-of-freedom HRA with a magnetic equivalent circuit to identify and analyze sources of non-linearities. On the basis of the verified model, solutions for an improved linear system behavior are analytically searched. Two linearized HRA designs are proposed, one with linear cross-section dependency and the other with hyperbolic air gap length dependency. Finite element method simulations are employed to evaluate the performance with respect to the linearity and the motor constant of these designs, showing factor 50 improved system linearity.

Effect of welding gap on electromagnetic pulse welding of a copper-aluminum alloy joint

ABSTRACT Electromagnetic pulse welding (EMPW) is commonly used for welding copper and aluminum alloy. The welding gap is important in the EMPW process. The research focused on the effect of welding gap on the welding process and the mechanical property of joints. During the EMPW experiments, the deformation, collision, and metal jet were recorded with a high-speed camera. The joint mechanical property was tested. SEM and EDS were employed to examine the bonding interface. Results indicated that the welding gap length did not significantly influence the aluminum alloy plate motion behavior when it was long enough. With the welding gap width increasing, the collision velocity initially increased and subsequently decreased, and the angle between the two plates when they first collided increased continuously. The intensity and duration of the metal jet and the joint mechanical properties also increased first and then decreased. The welding marks widened first and then narrowed.

Temporal characteristics of turbulent flow and moth orientation behaviour patterns with fluent simulation and moth-based moving model simulation

ObjectivePrevious research has explored the pheromone release patterns of female moths, revealing species-specific release frequencies and the transmission of temporal information through odourant plumes in turbulent flows. Varying the release frequency during the orientation process results in distinct orientation behaviours. Studies on moth movement patterns have determined that encounters and deviations from odour plumes elicit distinct reactions; the time interval between each movement pattern is measured as the “reaction time,” and the interval between each detection and loss of odourant plume is measured as the “gap length.” MethodsWe simulated turbulent flow at various release frequencies. Our efforts focused on establishing a model that could simulate the joint orientation movement under turbulent flow and intermittent plumes. We built an agent moving mechanism, including wind velocity information, with particular reference to the temporal parameter and orientation success efficiency. ResultsWe calculated the time threshold of each burst in different simulations under different wind velocities and release frequencies. The time structure characteristics of the plume along the turbulent flow vary depending on the distance from the source. We simulated walking agents in a turbulent environment and recorded their behaviour processes. The reaction time, release interval, and time threshold were related to the orientation results. ConclusionOn the basis of previous experimental results and our simulations, we conclude that the designated interval time likely enhances search efficiency. The complex and dynamic natural environment presents various opportunities for using this unique odour-source searching capability in different scenarios, potentially improving the control systems of odour-searching robots.

Torque and Eddy Current Behavior of a Magnet Rotating Axial Disk Type Magnetic Coupler: Analysis and Experimental Verification

This research explored the impact of air gap on torque and eddy current behavior of a magnet-north-pole rotating axial disk-type magnetic coupler using the magnetic equivalent circuit method. A magnetic equivalent circuit (MEC) model was developed to analyze the torque and induced eddy current behavior for the magnetic N-pole rotation angle 0° to 30° axial disk type magnetic coupler (MC). Torque equations were derived by combining Kirchhoff's law and the integral method, whereas induced eddy current equations were derived using Ampere's law. Flux leakage reluctance equations were obtained using an integral method. Furthermore, the study conducted 2D finite element simulations, and the results were validated against experimental data to ensure the accuracy and reliability of the proposed MEC model. Finally, the research findings suggested that an air gap length of 4 mm was an optimum length to obtain maximum torque and minimum magnetic saturation effects for a proposed MEC model of N-pole rotating axial disk type MC.

Allele-Selective Thiomorpholino Antisense Oligonucleotides as a Therapeutic Approach for Fused-in-Sarcoma Amyotrophic Lateral Sclerosis.

Pathogenic variations in the fused in sarcoma (FUS) gene are associated with rare and aggressive forms of amyotrophic lateral sclerosis (ALS). As FUS-ALS is a dominant disease, a targeted, allele-selective approach to FUS knockdown is most suitable. Antisense oligonucleotides (AOs) are a promising therapeutic platform for treating such diseases. In this study, we have explored the potential for allele-selective knockdown of FUS. Gapmer-type AOs targeted to two common neutral polymorphisms in FUS were designed and evaluated in human fibroblasts. AOs had either methoxyethyl (MOE) or thiomorpholino (TMO) modifications. We found that the TMO modification improved allele selectivity and efficacy for the lead sequences when compared to the MOE counterparts. After TMO-modified gapmer knockdown of the target allele, up to 93% of FUS transcripts detected were from the non-target allele. Compared to MOE-modified AOs, the TMO-modified AOs also demonstrated reduced formation of structured nuclear inclusions and SFPQ aggregation that can be triggered by phosphorothioate-containing AOs. How overall length and gap length of the TMO-modified AOs affected allele selectivity, efficiency and off-target gene knockdown was also evaluated. We have shown that allele-selective knockdown of FUS may be a viable therapeutic strategy for treating FUS-ALS and demonstrated the benefits of the TMO modification for allele-selective applications.

Management Strategies and Outcomes of Distal Congenital Esophageal Strictures in the Setting of Long-gap Esophageal Atresia

BackgroundThe management of neonates with long-gap esophageal atresia (LGEA) combined with distal congenital esophageal strictures (CES) is challenging. We sought to review our approach for this rare set of anomalies. MethodsWe reviewed children with LGEA + CES surgically treated at two institutions (2018–2024). LGEA repair was performed using the Foker technique (traction-induced esophageal lengthening). A CES strategy was chosen based on preoperative evaluations and intraoperative findings. The configuration and length of the CES were assessed using retrograde flexible esophagoscopy via gastrostomy with contrast fluoroscopy. ResultsEight patients (75% male) with LGEA + CES were treated: Four had type A and four had type B EA. Median gap length was 3.5 cm. Three underwent thoracoscopic esophageal lengthening. After a median follow-up of 18 months (IQR: 9–25), all retained their native esophagus. However, those who had CES resection concurrent with the lengthening process or at the time of EA anastomosis had more challenging perioperative courses: one required additional time on traction and another required esophageal anastomotic stricture resection. ConclusionsOur experience with LGEA and distal CES emphasizes tailoring surgical approaches to each patient's unique condition, avoiding a one-size-fits-all strategy. However, if the esophageal tissue above the distal CES is in good condition, our preference has shifted towards retaining the CES during traction, performing gentle dilation at anastomosis time, and conducting definitive endoscopic management subsequently. We would caution against making the assumption that salvage of the native esophagus is not possible or that resection of the CES is always needed. Level of EvidenceLevel III.

Correlation of Tracheomalacia Severity With Esophageal Gap Length as Assessed by Ultrashort Echo-time MRI

IntroductionTracheomalacia severity is difficult to quantify, however, ultrashort echo-time MRI objectively quantifies tracheomalacia in infants without sedation, radiation, or intubation. Patients with tracheoesophageal fistula and esophageal atresia (TEF/EA) commonly have tracheomalacia, however, the relationship between tracheomalacia severity and esophageal atresia has not been well defined. The primary objective of this study was to establish the relationship between EA and tracheomalacia severity and identify possible predictors of tracheomalacia severity. MethodsA retrospective review of neonates with TEF/EA who had previously undergone UTE MRI was performed. The trachea was divided into thirds. Maximal eccentricity in each third was calculated by measuring the anterior posterior dimension (MinD) and dividing it by the maximum width of the trachea (MaxD). Frequency of respiratory related admissions, number of upper respiratory infections, and number of steroids courses were quantified in addition to eccentricity in short and long gap esophageal atresia patients. ResultsA total of 16 TEF/EA patients were included. Patients with long gap esophageal atresia had more severe tracheomalacia than short gap as measured by eccentricity in the upper (0.60 vs 0.72, p = 0.03), middle (0.48 vs 0.61, p = 0.02), and lower (0.5 vs 0.65, p = 0.01) trachea. Long gap esophageal atresia patients had more frequent respiratory readmissions (1.87 admissions/year vs 0.54 admissions/year) (p = 0.03). Following TEF/EA repair the trachea was less eccentric in the upper third (0.64 pre, 0.79 post, p < 0.01) and more eccentric in the lower third (0.69 pre, 0.56 post, p < 0.01). ConclusionDifferences in esophageal gap and repair status correlate with airway eccentricity and tracheomalacia symptoms. Level of Evidence4.

Llarull type theorems on complete manifolds with positive scalar curvature

In this paper, without assuming that manifolds are spin, we prove that if a compact orientable, and connected Riemannian manifold ( M n , g ) (M^{n},g) with scalar curvature R g ≥ 6 R_{g}\geq 6 admits a non-zero degree and 1 1 -Lipschitz map to ( S 3 × T n − 3 , g S 3 + g T n − 3 ) (\mathbb {S}^{3}\times \mathbb {T}^{n-3},g_{\mathbb {S}^{3}}+g_{\mathbb {T}^{n-3}}) , for 4 ≤ n ≤ 7 4\leq n\leq 7 , then ( M n , g ) (M^{n},g) is locally isometric to S 3 × T n − 3 \mathbb {S}^{3}\times \mathbb {T}^{n-3} . Similar results are established for non-compact cases as ( S 3 × R n − 3 , g S 3 + g R n − 3 ) (\mathbb {S}^{3}\times \mathbb {R}^{n-3},g_{\mathbb {S}^{3}}+g_{\mathbb {R}^{n-3}}) being model spaces. We observe that the results differ significantly when n = 4 n=4 compared to n ≥ 5 n\geq 5 . Our results imply that the ϵ \epsilon -gap length extremality of the standard S 3 \mathbb {S}^3 is stable under the Riemannian product with R m \mathbb {R}^m , 1 ≤ m ≤ 4 1\leq m\leq 4 (see D 3 D_{3} . Question in Gromov’s paper [Foundations of mathematics and physics one century after Hilbert, Spring, Cham, 2018, p. 153]).

Geometric factors affecting CO2 separation in a supersonic separator

The current work evaluates a potential carbon separation approach with swirl flows and spontaneous condensation. Euler-Euler model is established to depict the spontaneous condensation. By combining Euler-Lagrange model and Euler-Euler model, the droplet motion behavior is predicted, and the influence of separator structure including swirl generator and gap length on the separation efficiency of CO2 is quantified. The flue gas expands under pressure to create a non-equilibrium system, which leads to the emergence of CO2 condensation nuclei. On the surface of nuclei, metastable molecules aggregate and promote the growth of CO2 droplets. Based on the force on droplets, the droplet behavior can be separated into three categories: impacting the straight tube wall, entering the collector and entering the diffuser. When the angle of swirl generator and gap length rises by 315° and 3.75 mm respectively, the separation efficiency rises by 60.3 % and 48.6 %, respectively.