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Research on the operation condition indicator for centrifugal pump based on sensorless monitoring technology

PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART E-JOURNAL OF PROCESS MECHANICAL ENGINEERING 2021年第2期235卷 514-526页

作者： Luo, Yin Han, Yuejiang Zhang, Fan Jiangsu Univ Res Ctr Fluid Machinery Engn & Technol Zhenjiang 212013 Jiangsu Peoples R China

A centrifugal pump operates under off-design operation conditions would lead to flow instability, additional energy loss or mechanical damage. Early detection is of great importance to its operation efficiency and safety. Sensorless monitoring technology based on motor current signature analysis (MCSA) is a cost-effective and non-intrusive technology to monitor motor-driven devices. However, existing researches on MCSA for centrifugal pump usually realize their monitoring function through complicated time-frequency or energy analysis, they stop short of an indicator that has less calculation cost and definite physical significance compatible with the pump's operation condition. In response to the limitations, this paper aimed at establishing such indicator for centrifugal pump based on MCSA. Theoretical analysis, CFD simulation and experiments were conducted to study the characteristics of pump torque and motor stator current, whose results suggest that the torque fluctuation frequency characteristics would be transmitted to motor stator current by electromagnetic coupling effect, and distribute as sidebands in current spectrum through power frequency modulation. As a result, torque disturbance caused by off-design operation would be reflected as stronger harmonic and noise distortion of motor stator current, and the distortion intensity could be quantified and employed as the operation condition indicator (OCI) for centrifugal pump. Experimental results show that the OCI has its lowest value under the design operation condition, and gradually increases as the pump's operation condition getting worse. Such change law agrees well with the efficiency characteristics of centrifugal pump, which provides a new thought for the operation monitoring of centrifugal pump based on MCSA. The proposed indicator could be directly obtained from the current signal and easily calculated, which is more appropriate for application and probably more preferred for industry compared to t

关键词： Centrifugal pump sensorless monitoring technology motor current signature analysis operation condition indicator computational fluid dynamics simulation harmonic and noise distortion

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Evaluating Unsteady fluid Dynamic Forces in Viscous Flows from the Vorticity Field

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AIAA JOURNAL 2021年第1期59卷 22-33页

作者： Li, Juan Wang, Yinan Graham, Michael Zhao, Xiaowei Univ Warwick Sch Engn Coventry CV4 7AL W Midlands England Imperial Coll Dept Aeronaut London SW7 2BY England

The vortex force map (VFM) method is a promising low-cost technique for predicting unsteady aerodynamic load from the vorticity field. Developed under potential flow assumption and applied to high-resolution computational fluid dynamics (CFD) data, the original VFM method needs to be further explored for viscous flows, especially at low Reynolds numbers and with incomplete knowledge of the flow data. In this paper, the VFM method is extended to general viscous flows, with both forces contributed from vorticity in the flowfield and on the body surface considered. We find that viscosity contributes to not only the skin-friction force but also a pressure force term. We also show that the extended vortex pressure force maps for general flow problems without the potential flow assumption lead to vanishing contributions from the far-field. The extended VFM method is applied to CFD flowfields for the starting flow of a cylinder and a NACA0012 airfoil, and it is used to analyze the force contribution effect of a given vortex. Moreover, acceptable accuracy of the method on truncated domains and under coarse sampling of typical particle image velocimetry measurement size is demonstrated.

关键词： Two Dimensional Flow Kutta Condition Starting Vortex computational fluid dynamics simulation Freestream Velocity Thin Airfoil Theory Particle Image Velocimetry Skin Friction Force Viscosity Lift Coefficient

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Quasi-Steady Effective Angle of Attack and Its Use in Lift-Equivalent Motion Design

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AIAA JOURNAL 2021年第7期59卷 2613-2626页

作者： Xu, Xianzhang Lagor, Francis D. Univ Buffalo State Univ New York Dept Mech & Aerosp Engn Buffalo NY 14260 USA

The effective angle of attack of an airfoil is a composite mathematical expression from quasi-steady thin-airfoil theory that combines the geometric contribution to the angle of attack with pitching and plunging effects. For a maneuvering airfoil, the instantaneous effective angle of attack is a virtual angle that corresponds to the equivalent lift based on a steady, lift versus angle-of-attack curve. The existing expression for effective angle of attack depends on attached-flow, thin-airfoil, small-angle, and small-camber-slope assumptions. This paper derives a new expression for and effective angle of attack that relaxes the small-angle and small-camber-slope assumptions. The new expression includes effects from pitching, plunging, and surging motions, as well as spatial nonuniformity of the flow. The proposed expression simplifies to the existing quasi-steady expression by invoking the appropriate assumptions. Furthermore, the proposed expression leads to a replacement for the classic zero-lift angle-of-attack equation for steady flow past a thin airfoil, which is compared to experimental values for cambered NACA four-digit airfoils. The new expression is also used for lift-equivalent motion design for a maneuvering airfoil to emulate the effective angle of attack of a nonmaneuvering airfoil encountering a transverse gust under a quasi-steady assumption. computational fluid dynamics simulations support the use of the proposed effective angle-of-attack expression for lift-equivalent motion design, subject to an attached-flow assumption.

关键词： Lift Coefficient Thin Airfoil Theory Airfoil Geometry Flow Conditions computational fluid dynamics simulation Aerodynamic Characteristics Vortex Modeling Reynolds Averaged Navier Stokes Optimal Control Comsol Multiphysics

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Thermal Performance Assessment of a Tubular Heat Exchanger Fitted with Flower Baffles

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2021年第4期35卷 726-734页

作者： Sahel, Djamel Univ Amar Telidji Laghouat Laghouat 00003 Algeria UST Oran MB Dept Tech Sci Gaseous Fuels & Environm Lab LCGE Bir El Djir 31000 Algeria

This paper presents a numerical study of the hydrothermal air-side performance of a tubular heat exchanger fitted with flower baffles (FBs). The investigation was done by testing in-line and staggered FB arrangements for various baffles' pitch ratios (PR = 1, 1.5, 2, 2.5, and 3) with Reynolds number Re ranging from 3000 to 15,000. The results indicate that the use of the FBs leads to stirring the stagnated zones downstream of the baffles, and improving the air mixture close to the tube walls, which, by consequence, presents an efficient solution to improve the thermal transfer coefficients. Also, the PR rise with a fixed blockage ratio of 0.5 leads to an increase of both the Nusselt number Nu and friction factor f values. The highest thermal performance factor. of 1.77 is achieved by using the in-line baffle arrangement at PR = 2.5, BR = 0.5, and Re = 3000. Finally, and for other useful applications, reliable correlations have been developed to predict Nusselt number and friction factor.

关键词： Thermal Performance Finned Tube Heat Exchangers Convection Heat Transfer Coefficient Friction Factor Reynolds Number Reynolds Averaged Navier Stokes Vortex Generators Numerical Modeling Flow Characteristics computational fluid dynamics simulation

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Three-dimensional computational fluid dynamics investigation of hydrodynamics behaviour of gas-solid flow in fluidized bed of Geldart D particles

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART E-JOURNAL OF PROCESS MECHANICAL ENGINEERING 2021年第4期235卷 1005-1016页

作者： Aiche, Fazia Belaadi, Salah Lalaoua, Adel Berrouk, Abdallah Sofiane Azzi, Abdelwahid Univ Sci & Technol Houari Boumediene Fac Mech Engn & Proc Engn Algiers Algeria Univ Bejaia Fac Technol Bejaia Algeria Khalifa Univ Sci & Technol Mech Engn Dept Abu Dhabi U Arab Emirates Khalifa Univ Sci & Technol Ctr Catalysis & Separat Abu Dhabi U Arab Emirates

fluidized beds are widely used in many industrial processes as they ensure the desirable high-intensity heat and mass transfers between gas and particles and offer the possibility to perform operations in a continuous mode and powders recycling. Some of these industrial processes use Geldart D type of powders and operate in the slugging mode. This paper presents a 3 D numerical model of gas-solid flows in a fluidized bed based on the Two-fluid Model (TFM). Turbulence modeling (k- epsilon) was used to predict flow behavior in fluidized bed of Geldart D particles. The solid phase consists of Geldart D powders and the gas flow is in a slug regime. The numerical results are validated against the experimental work of Azzi et al. Model predictions on flow patterns, bed expansion, volume fraction time series and pressure drop fluctuations are presented and discussed in details in order to demonstrate the cyclic process of slug formation (onset, growth, rising and bursting of slugs) and its effects on the overall performance of beds fluidizing Geldart D type of powders.

关键词： fluidized bed Geldart D particles computational fluid dynamics simulation two-fluid model bed expansion slugging mode

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computational modeling and experimental characterization of fluid dynamics in micro-CT scanned scaffolds within a multiple-sample airlift perfusion bioreactor

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BIOCHEMICAL ENGINEERING JOURNAL 2023年 191卷

作者： Capuana, Elisa Campora, Simona Catanzaro, Giorgio Lopresti, Francesco Conoscenti, Gioacchino Ghersi, Giulio La Carrubba, Vincenzo Brucato, Valerio Pavia, Francesco Carfi Univ Palermo Dept Engn RU INSTM Viale Sci I-90133 Palermo Italy Consorzio Univ Caltanissetta Corso Vittorio Emuanuele 92 I-93100 Caltanissetta Italy Univ Palermo Abiel Srl Viale Sci Ed 16 I-90128 Palermo Italy Univ Palermo Dept Biol Chem & Pharmaceut Sci & Technol STEBICEF Viale Sci Ed 16 I-90128 Palermo Italy

The perfusion of flow during cell culture induces cell proliferation and enhances cellular activity. Perfusion bioreactors offer a controlled dynamic environment for reliable in vitro applications in the tissue engineering field. In this work, to evaluate the effects of the operating parameters of a custom-made bioreactor, numerical simulations were performed to solve the fluid velocity profile inside the bioreactor containing multi-grid support that allows allocating of multiple seeded scaffolds at the same time. The perfusion system exhibited a uniform distribution of liquid velocities within the regions, suitable for cell growth on seeded scaffolds. The effects of the porous microstructure of scaffolds on the extracellular matrix deposition also play a crucial role during perfusion cultures. In the present study, a numerical simulation was implemented at the pore level of the scaffold for fluid flow through porous media during perfused culture. Micro-computed tomography was used to obtain the digital 3D image of the complex geometry of a PLLA scaffold, offering a detailed analysis from a volume-based meth-odology without simplifications of the results as for pore or Darcy's law-models. Predictions about the uniformity of the flow field through the scaffolds-bioreactor system have been assessed by quantifying the cell viability of a perfusion culture while using pre-osteoblastic cells seeded on 24 PLLA scaffolds for up to 6 days.

关键词： computational fluid dynamics simulation Micro-computed tomography Airlift perfusion bioreactor Dynamic cell culture Tissue Engineering

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Hydrodynamic design of down-flow packed bed reactor regulated the biohydrogen production and microbial enrichment

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ENERGY 2023年 271卷

作者： Zhang, Zexi Ding, Ke Ma, Xiaojun Tang, Shuai Wang, Zixin Lu, Haifeng Jiang, Weizhong Si, Buchun China Agr Univ Coll Water Resources & Civil Engn Key Lab Agr Engn Struct & Environm Minist Agr & Rural Affairs Beijing 100083 Peoples R China Sanya Inst China Agr Univ Sanya 572020 Hainan Peoples R China Univ Illinois Dept Mech Sci & Engn Champaign IL 61801 USA Beijing Union Univ Coll Biochem Engn Beijing 100023 Peoples R China Univ Illinois Dept Agr & Biol Engn Urbana IL 61801 USA

The hydrodynamic regulation, by adjusting microbial carrier filling strategies, plays a critical role in packed bed reactors (PBRs) for biohydrogen production, but the relationship between hydrodynamic characteristics, mi-crobial enrichment and hydrogen production has not been fully understood. In this study, hydrodynamic characteristics of different filling strategies in PBRs were designed and analyzed using computational fluid dy-namics (CFD) simulation. Further, the hydrogen production and microbial structure during the continuous operation of PBRs with different filling approaches were compared. The optimal hydrodynamic design was PBR with vertical filling strategy (PBR-V) which had a more evenly distributed velocity magnitude than that with horizontal (PBR-H) arrangement, and it benefited mass transfer and further improved the reactor performance. PBR-V achieved the maximum hydrogen yield of 2.6 mol/mol glucose since the hydrodynamic design favored hydrogen production (butyrate-type fermentation) and suppressed hydrogen-consuming reactions (propionate -type fermentation). In addition, the PBR-V had a quicker start-up and favored the biomass attachment to the filling carriers. A higher abundance of hydrogen producer Clostridiaceae (89.2%) in PBR-V during start-up than that in PBR-H was also confirmed. This study provides insight into hydrodynamic and microbial selection mechanisms, and guides the design of future anaerobic high-rate reactors for efficient biohydrogen production.

关键词： Packed bed reactor Hydrogen production Hydrodynamic design Microbial structure Dark fermentation computational fluid dynamics simulation

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Influence of natural ventilation design on the dispersion of pathogen-laden droplets in a coach bus

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SCIENCE OF THE TOTAL ENVIRONMENT 2023年 885卷 163827页

作者： Luo, Qiqi Yang, Xia Hang, Jian Fan, Xiaodan Luo, Zhiwen Gu, Zhongli Ou, Cuiyun Sun Yat Sen Univ Sch Atmospher Sci Southern Marine Sci & Engn Guangdong Lab Zhuhai Zhuhai Peoples R China Sun Yat Sen Univ Key Lab Trop Atmosphere Ocean Syst Minist Educ Zhuhai 519000 Peoples R China Guangdong Prov Engn Lab Air Pollut Control Guangzhou Peoples R China Cardiff Univ Welsh Sch Architecture Cardiff Wales Guangdong Fans Tech Agro Co Ltd Yunfu Peoples R China

Natural ventilation is an energy-efficient design approach to reduce infection risk (IR), but its optimized design in a coach bus environment is less studied. Based on a COVID-19 outbreak in a bus in Hunan, China, the indoor-outdoor coupled CFD modeling approach is adopted to comprehensively explore how optimized bus natural ventilation (e.g., opening/closing status of front/middle/rear windows (FW/MW/RW)) and ceiling wind catcher (WCH) affect the dispersion of pathogen -laden droplets (tracer gas, 5 mu m, 50 mu m) and IR. Other key influential factors including bus speed, infector's location, and ambient temperature (Tref) are also considered. Buses have unique natural ventilation airflow patterns: from bus rear to front, and air change rate per hour (ACH) increases linearly with bus speed. When driving at 60 km/h, ACH is only 6.14 h-1 and intake fractions of tracer gas (IFg) and 5 mu m droplets (IFd) are up to 3372 ppm and 1394 ppm with ventilation through leakages on skylights and no windows open. When FW and RW are both open, ACH increases by 43.5 times to 267.50 h-1, and IFg and IFd drop rapidly by 1-2 orders of magnitude compared to when no windows are open. Utilizing a wind catcher and opening front windows significantly increases ACH (up to 8.8 times) and reduces IF (5-30 times) com-pared to only opening front windows. When the infector locates at the bus front with FW open, IFg and IFd of all passengers are <10 ppm. More droplets suspend and further spread in a higher Tref environment. It is recommended to open two pairs of windows or open front windows and utilize the wind catcher to reduce IR in coach buses.

关键词： Droplet dispersion Window Infection risk Wind catcher Temperature computational fluid dynamics simulation

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Prioritizing Possible Force Models Error in Multiphase Flow Using Global Sensitivity Analysis

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AIAA JOURNAL 2021年第5期59卷 1749-1759页

作者： Nili, Samaun Park, Chanyoung Kim, Nam H. Haftka, Raphael T. Balachandar, S. Univ Florida Dept Mech & Aerosp Engn Gainesville FL 32611 USA

Modeling gas-particle interaction in an Eulerian-Lagrangian frame involves many approximate models. Hence, understanding the model form error is essential to improve the prediction capability. Often, a model by itself consists of several submodels where each submodel is subject to potential error. The potential errors can superimpose or compensate for each other over time, which makes it difficult to find a possible source of model form error. This study aims to quantify, rank, and isolate the contribution of error in each submodel to the error in the model prediction. The concept of global sensitivity analysis is extended by using it as a tool to isolate the most influential potential error in drag force submodels of a transient multiphase dispersed flow on particle cloud position. The possible errors of the submodels are modeled as uniformly distributed epistemic uncertainty, and their contributions to the quantity of interest are calculated in terms of sensitivity indices. We found that the most influential potential submodel error depends on time and the characteristic of the particle cloud.

关键词： Sensitivity Analysis Incompressible Flow Aerodynamic Force computational fluid dynamics simulation Numerical Modeling Heat Transfer Modeling Statistical Distributions Crack Growth fluid Flow Sandia National Laboratories

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Efficiency-Optimal Rigidity Configuration of Passive Torsional Flapping Wings

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AIAA JOURNAL 2021年第11期59卷 4354-4366页

作者： Zhao, Longfei Jiao, Zongxia Beihang Univ Res Inst Frontier Sci Beijing 100191 Peoples R China Beihang Univ Ningbo Inst Technol Ningbo 315800 Peoples R China

In this work, a simple analytical tool for the efficient, optimal design of passive torsional flapping wings, which is usually done with the complex fluid-structure interaction method, is proposed. For thin-skin-wrapped spar-rib wing structures, the propulsion efficiency was modeled based on the momentum theorem, and the wing passive torsion was modeled based on the thin-wall-tube torsional vibration theorem. A forward efficiency-optimal design method for passive torsional flapping wings was thereby developed. The proposed method was validated through numerical simulation and a wind-tunnel experiment for a 0.85-m-span flapping-wing model with multiple wing torsional rigidity configurations. The group with the torsional rigidity optimized by the presented method displayed the best efficiency performance. The proposed method has potential applications for the concept design and performance evaluation of flapping-wing aircraft.

关键词： Flapping Frequency Wind Tunnel Tests computational fluid dynamics simulation FSI Torsional Vibration Blade Element Theory Aerodynamic Efficiency Strouhal Numbers Center of Pressure UAV

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