scholarly journals Effect of Characteristic Phenomena and Temperature on Super-Cooled Large Droplet Icing on NACA0012 Airfoil and Axial Fan Blade

Aerospace ◽  
2020 ◽  
Vol 7 (7) ◽  
pp. 92 ◽  
Author(s):  
Toma Takahashi ◽  
Koji Fukudome ◽  
Hiroya Mamori ◽  
Naoya Fukushima ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Weak Coupling ◽  
Reasonable Agreement ◽  
Collection Efficiency ◽  
Axial Fan ◽  
Droplet Motion ◽  
Naca0012 Airfoil ◽  
Simulation Results ◽  
Fan Blade ◽  
Thermodynamic Computation

Icing simulations involving super-cooled large droplets (SLDs) on a NACA0012 airfoil and a commercial axial fan were performed considering the characteristic behavior of SLD icing (i.e., splash-bounce, deformation, and breakup). The simulations were performed considering weak coupling between flow field and droplet motion. The flow field was computed using the Eulerian method, wherein the droplet motion was simulated via the Lagrangian method. To represent the ice shape, an extended Messinger model was used for thermodynamic computation. The ice shape and collection efficiency of the NACA0012 airfoil derived using the icing simulation exhibited a reasonable agreement with the existing experimental data. The icing simulation results for the axial fan, in terms of distribution of ice on the blade and its influence on the flow field, indicated that flow separation occurred, and the mass flow rate of the flow passage decreased. Moreover, the splash and bounce phenomena considerably influenced the icing process; however, the effect of the deformation and breakup phenomena was negligibly small. In terms of the effect of the SLDs on the icing phenomena, it was noted that, with the decrease in the SLD temperature (from −5 °C to −15 °C), the number of adhering SLDs increased, whereas the number of splashing and bouncing SLDs decreased.

Study on Simulation and Measurement of Hydropower Plant Ventilation System

2013 ◽  
Author(s):  
Guangjie Peng ◽  
Zhengwei Wang ◽  
Liming Zhai ◽  
Fei Lin
Keyword(s):  
Field Theory ◽  
Flow Field ◽  
Steady Flow ◽  
Reasonable Agreement ◽  
Design Method ◽  
Ventilation System ◽  
Hydropower Plant ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results

With the method of Computational Fluid Dynamics (CFD), this paper simulated the internal steady flow field in the switch room of the ChengGuan hydropower plant before and after improvement in Shaxian of Fujian province, and did the same to the temperature distribution and flow rules. It demonstrates that the simulation results are in reasonable agreement with the experimental results, which shows the correctness of design method using steady flow field theory. On the basis, it also improved the ventilation plan and measured the results, proving that ventilation was reinforced significantly after improvement. This method can be used to guide and optimize the design for the ventilation in hydropower plant.

scholarly journals The Effect of Tilt Angle of Axial Fan Blades on Air Flow Distribution in the Cabinet Dryer: Simulation Study Using Computational Fluid Dynamics

Teknomekanik ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 8-13
Author(s):  
Agus Dian Saputra ◽  
Adjar Pratoto ◽  
Gusriwandi Gusriwandi ◽  
Joko Suprianto
Keyword(s):  
Flow Distribution ◽  
Air Distribution ◽  
Drying Rate ◽  
Simple Construction ◽  
Blade Angle ◽  
Axial Fan ◽  
Airflow Distribution ◽  
Simulation Results ◽  
Fan Blade ◽  
Drying Chamber

The application of tray dryer is widely used for various commodity dryers due to its simple construction. However, one of the drawbacks of tray dryer is the uneven airflow distribution in the drying chamber which results in the drying rate in the tray position being unequal. As a result, the degree of dryness of the product also varies. This study investigated the effect of fan blade angle on airflow distribution in the dryer cabin through numerical simulations. The axial fan diameter was 350 mm with a thickness of 20 mm. The variations of axial fan blades used were 10o, 20o, 30o and 45o. The number of blades used was 4, and the allowable airflow limit was 2 m x 1 m x 1 m, with an axial fan rotation of 500rpm. Based on the simulation results, the 45o fan angle had good air distribution results compared to the 10o, 20o, and 30o fan angles. Likewise, the distribution of air produced by the fan was evenly distributed, because the greater the angle of the fan used for the dryer, the better the results would be obtained.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

The Research about the Wind Turbines Pitch Control

2013 ◽  
Vol 773 ◽  
pp. 87-90
Author(s):  
Chen Wang ◽  
De Zhou Meng ◽  
Xu Fang Bo
Keyword(s):  
Wind Power ◽  
Pid Control ◽  
Control Algorithm ◽  
Uneven Distribution ◽  
Pitch Control ◽  
Experimental Platform ◽  
Simulation Results ◽  
Pitch System ◽  
Fan Blade ◽  
Variable Pitch Control

Based on the background of wind power, considering the wind blade sweep area on the uneven distribution, this paper is using the PID control algorithm to control the pitch system. At the same time, this paper is using Siemens SCL to programming, simulating on the experimental platform. Simulation results show the validity of the theory and the feasibility of the system, realizing variable pitch control of fan blade.

Dynamic Stall Simulation of Flow Over NACA0012 Airfoil at 1 Million Reynolds Number

2015 ◽  
Author(s):  
Venkata Ravishankar Kasibhotla ◽  
Danesh Tafti
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Dynamic Stall ◽  
Sharp Drop ◽  
Airfoil Surface ◽  
Naca0012 Airfoil ◽  
Reduced Frequency ◽  
Edge Vortex

The paper is concerned with the prediction and analysis of dynamic stall of flow past a pitching NACA0012 airfoil at 1 million Reynolds number based on the chord length of the airfoil and at reduced frequency of 0.25 in a three dimensional flow field. The turbulence in the flow field is resolved using large eddy simulations with the dynamic Smagorinsky model at the sub grid scale. The development of dynamic stall vortex, shedding and reattachment as predicted by the present study are discussed in detail. This study has shown that the downstroke phase of the pitching motion is strongly three dimensional and is highly complex, whereas the flow is practically two dimensional during the upstroke. The lift coefficient agrees well with the measurements during the upstroke. However, there are differences during the downstroke. The computed lift coefficient undergoes a sharp drop during the start of the downstroke as the convected leading edge vortex moves away from the airfoil surface. This is followed by a recovery of the lift coefficient with the formation of a secondary trailing edge vortex. While these dynamics are clearly reflected in the predicted lift coefficient, the experimental evolution of lift during the downstroke maintains a fairly smooth and monotonic decrease in the lift coefficient with no lift recovery. The simulations also show that the reattachment process of the stalled airfoil is completed before the start of the upstroke in the subsequent cycle due to the high reduced frequency of the pitching cycle.

Surface Coating Effect on Protection of Icing for Axial Fan Blade

2011 ◽  
Author(s):  
Takeshi Murooka ◽  
Shinichirou Shishido ◽  
Riho Hiramoto ◽  
Takakazu Minoya
Keyword(s):  
Surface Coating ◽  
Axial Fan ◽  
Fan Blade

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

Numerical Simulation of Airborne Salt Particle Behavior in Dry Gauze Method Using Porous Media Model

2021 ◽  
pp. 1-37
Author(s):  
Yuta Tsubokura ◽  
Kyohei Noguchi ◽  
Tomomi Yagi
Keyword(s):  
Porous Media ◽  
Flow Field ◽  
Collection Efficiency ◽  
Steel Structures ◽  
Salt Particle ◽  
Wooden Frame ◽  
Collection Device ◽  
Porous Media Model ◽  
Corrosion Of Steel ◽  
Porous Media Method

Abstract Airborne salt accelerates the corrosion of steel materials and, thus, must be quantitatively evaluated for the management of steel structures. In Japan, the dry gauze method, which uses a gauze embedded in a wooden frame, is often used to evaluate the amount of airborne salt. However, its collection efficiency for salt particles has not been verified owing to the complex airflows around the device. Therefore, as a first step to clarify the collection efficiency, the authors simulated the flow field around the collection device using computational fluid dynamics. In this study, the gauze was modeled as a porous medium to reduce the computational costs. Wind tunnel tests were performed to obtain the pressure loss coefficients of the gauze, which is necessary for the porous media method. Subsequently, particle tracking was performed in the calculated flow field, and the collection efficiency was evaluated under the condition of a filtration efficiency of 100%. The flow fields around the device were accurately reproduced using the porous media model, which considered both the tangential and normal resistances of the gauze. This result suggests that the tangential resistance must be considered in the porous media model when the porosity of an object is small, even if the thickness is small. The dependence of collection efficiency on wind speed and direction was quantitatively evaluated. The results showed that the collection efficiency was greatly affected by the complicated flow field around the device due to the combination of the gauze and wooden frame.

Numerical Simulation of Powder Dispersion Performance by Different Mesh Types

2016 ◽  
Vol 680 ◽  
pp. 82-85
Author(s):  
Jian Cai ◽  
Lan Chen ◽  
Umezuruike Linus Opara
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Fine Particle ◽  
Particle Deposition ◽  
Tetrahedral Mesh ◽  
Computational Time ◽  
Kinetic Characteristics ◽  
Powder Dispersion ◽  
Simulation Results ◽  
Time Accuracy

OBJECTIVE To investigate the influence of mesh type on numerical simulating the dispersion performance of micro-powders through a home-made tube. METHODS With the computational fluid dynamics (CFD) method, a powder dispersion tube was meshed in three different types, namely, tetrahedral, unstructured hexahedral and prismatic-tetrahedral hybrid meshes. The inner flow field and the kinetic characteristics of the particles were investigated. Results of the numerical simulation were compared with literature evidences. RESULTS The results showed that using tetrahedral mesh had the highest computational efficiency, while employing the unstructured hexahedral mesh obtained more accurate outlet velocity. The simulation results of the inner flow field and the kinetic characteristics of the particles were slightly different among the three mesh types. The calculated particle velocity using the tetrahedral mesh had the best correlation with the changing trend of the fine particle mass in the first 4 stages of the new generation impactor (NGI) (R2 = 0.91 and 0.89 for powder A and B, respectively). Conclusions Mesh type affected computational time, accuracy of simulation results and the prediction abilities of fine particle deposition.

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