scholarly journals NUMERICAL INVESTIGATION OF THE EFFECTS OF GEOMETRICAL PARAMETERS ON THE VORTEX SEPARATION PHENOMENON INSIDE A RANQUE-HILSCH VORTEX TUBE USED AS AN AIR SEPARATOR IN A HELICOPTER’S ENGINE

Aviation ◽  
2018 ◽  
Vol 22 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Adib Bazgir ◽  
Nader Nabhani
Keyword(s):  
Vortex Tube ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Geometrical Parameters ◽  
Cfd Model ◽  
Steady State Condition ◽  
Axial Angle ◽  
Temperature Reduction ◽  
Vortex Separation

Air separators are fitted to helicopter engine intakes to remove potentially harmful dust from the influent air. Their use is necessary in desert environments to eliminate the risk of rapid engine wear and subsequent power deterioration. However, their employment is concomitant with an inherent loss in inlet pressure and, in some cases, auxiliary power. There are three main technologies: vortex tubes, barrier filters, and integrated inlet particle separators. In this work, a vortex tube is investigated numerically. The study was conducted on the number and axial angle of inlet nozzles. Two and three-dimensional models are investigated at a steady state condition then the standard k-ε turbulence model is utilised for determining the flow and temperature fields. The finite volume method base on a Computational Fluid Dynamic (CFD) model is verified through the comparison with experimental data and numerical results of a vortex tube, reported in literature sources. Increasing the number of inlet nozzles, increases the sensitivity of the temperature reduction and the highest possible temperature reduction can be obtained. A vortex tube with an axial angle inlet nozzle of yields better performance. The numerical simulation results indicated that the CFD model is capable of predicting the vortex separation phenomenon inside a Ranque-Hilsch vortex tube with different geometrical parameters.

Thermal and Fluid Dynamic Analysis on Impinging Jet for Aircraft Anti-Icing

2010 ◽  
Author(s):  
Assunta Andreozzi ◽  
Fabio Lucibello ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Mario Roma
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Wing Surface ◽  
Temperature Fields ◽  
Ice Formation ◽  
Computational Domain ◽  
System A ◽  
Wing Profile

Ice formation on airplane wing profile is a very dangerous condition because of the change in the profile aerodynamic, so it’s necessary to avoid ice formation on the wings. The hardest condition ice formation are at altitudes between 10.000 and 15.000 ft and at temperature between 0° C and −15° C, because they are particularly suitable for ice formation. In this paper an anti-icing system based on hot air impinging jets on internal wing surface is analyzed in order to check the efficiency of the system. A numerical model is given in order to evaluate the thermal and fluid dynamic behaviors of the impinging jet inside the wing panel. A wing profile with an angle of attack of 4.50° is taken into account with a free stream temperature of 258 K. A piccolo tube with a diameter of 1.00 inch and air temperature of 523 K and at variable distance from the wall of the wing profile, is considered for anti-icing system. A structured mesh is used in the discretization of the computational domain for the two-dimensional and three-dimensional case. A steady state solution with k-ε RNG turbulent model has been found. Numerical simulations of a two and a three dimensional model of an aircraft wing has been carried out taking into account the external convective exchange by means of an average coefficient on the external surface and thermo-fluid dynamic field inside the wing due to the anti-icing system. The analysis is performed by means of the FLUENT code in order to find the optimal geometrical configuration to avoid the ice formation on the external wing surface. Results are presented in terms of temperature fields and wall temperature and air velocity profiles along the wing surfaces.

scholarly journals Experimental Analysis and CFD Modeling for Conventional Basin-Type Solar Still

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5734
Author(s):  
Mahmoud S. El-Sebaey ◽  
Asko Ellman ◽  
Ahmed Hegazy ◽  
Tarek Ghonim
Keyword(s):  
Fresh Water ◽  
Water Depth ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Solar Still ◽  
Cfd Model ◽  
Climate Conditions ◽  
Experimental Values ◽  
Multi Phase

With the rising population, environmental pollution, and social development, potable water is reducing and being contaminated day by day continually. Thus, several researchers have focused their studies on seas and oceans in order to get potable fresh water by desalination of their saltwater. Solar still of basin type is one of the available technologies to purify water because of free solar energy. The computational fluid dynamic CFD model of the solar still can significantly improve means for optimization of the solar still structure because it reduces the need for conducting large amount of experiments. Therefore, the main purpose of this study is presenting a multi-phase, three-dimensional CFD model, which predicts the performance of the solar still without using any experimental measurements, depending on the CFD solar radiation model. Simulated results are compared with experimental values of water and glass cover temperatures and yield of fresh water in climate conditions of Sheben El-Kom, Egypt (latitude 30.5° N and longitude 31.01° E). The simulation results were found to be in acceptable agreement with the experimental measured data. The results indicated that the daily simulated and experimental accumulated productivities of the single-slope solar still were found to be 1.982 and 1.785 L/m2 at a water depth of 2 cm. In addition, the simulated and experimental daily efficiency were around 16.79% and 15.5%, respectively, for the tested water depth.

scholarly journals Computational Fluid Dynamic Prediction and Physical Mechanisms Consideration of Thermal Separation and Heat Transfer Processes Inside Divergent, Straight, and Convergent Ranque–Hilsch Vortex Tubes

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Adib Bazgir ◽  
Nader Nabhani ◽  
Bahamin Bazooyar ◽  
Ali Heydari
Keyword(s):  
Vortex Tube ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Numerical Data ◽  
Dynamic Prediction ◽  
Temperature Separation ◽  
Flow Phenomena ◽  
Stream Lines ◽  
Physical Phenomena ◽  
Vortex Tubes

AbstractThe design of Ranque–Hilsch vortex tube (RHVT) seems to be interesting for refrigeration and air conditioning purposes in industry. Improving thermal efficiency of the vortex tubes could increase the operability of these innovative facilities for a wider heat and cooling demand to this end; it is of an interest to understand the physical phenomena of thermal and flow patterns inside a vortex tube. In this work, the flow phenomena and the thermal energy transfer in RHVT are studied for three RHVT: straight, divergent, and convergent vortex tubes. A three-dimensional numerical analysis of swirling or vortex flow is performed, verified, and validated against previous experimental and numerical data reported in literature. The flow field and the temperature separation inside an RHVT for different configuration of straight, five angles of divergent hot tube (1 deg, 2 deg, 3 deg, 4 deg, and 6 deg) and five angle of convergent hot tube (0.5 deg, 0.8 deg, 1 deg, 1.5 deg, and 2 deg) are investigated. The thermal performance for all investigated RHVTs configuration is determined and quantitatively assessed via visualizing the stream lines for all three scenarios.

Computerized Fluid Dynamic Study of Parameter Effects on the Performance of Coaxial Propellers

2020 ◽  
Vol 17 (7) ◽  
pp. 3237-3242
Author(s):  
Young-Tae Kim ◽  
Chang Hwan Park ◽  
Hak Yoon Kim
Keyword(s):  
Pitch Angle ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Steady State Condition ◽  
Performance Variation ◽  
Air Vehicle ◽  
Program Star ◽  
And Control

The computerized fluid dynamic (CFD) analysis was performed for 1.8 m diameter coaxial propellers to be applied to the multi-copter type Personal Air Vehicle (PAV) having conceptually 600 kg of Maximum Take-Off Weight (MTOW). Methods/Statistical analysis: Using the commercial CFD program STAR-CCM+ (13.03.11), the coaxial propellers were analyzed at the same RPM under the steady state condition. The three-dimensional Compressible Reynolds Mean Navier-Stokes equation was applied and the Moving Reference Frame (MRF) technique was used. With the optimum single pitch angle of upper propeller, the lower propeller’s pitch was changed for the varying propeller spacing to identify the performance variation and the interference effect. The lower propeller has to be different pitch setting other than the upper propeller’s optimum pitch angle because of the interfered flow effect between propellers. The propeller spacing is not so sensitive to efficiency if the spacing is more than 0.25 of propeller diameter. Study shows that the identified pitches and spacing of coaxial propellers are essential for designing the configuration and control of multi-copter type PAV which uses variable pitch propellers for safety and efficiency.

Parameter Selection of Fluid Dynamic Sealing for a Submersible Slurry Pump

2006 ◽  
Author(s):  
Hongjuan Ran ◽  
Xianwu Luo ◽  
Hongyuan Xu ◽  
Wen Luo ◽  
Junqi Peng
Keyword(s):  
Solid Particle ◽  
Yellow River ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Design Concept ◽  
Geometrical Parameters ◽  
Mechanical Seal ◽  
River Sand ◽  
Actual Operation ◽  
Selection Of

In the case of slurry pumps, mechanical seal is usually used. It is well known that the pump is very dangerous if any solid particle enters the seal. Nowadays, people prefer to install a fluid dynamic sealing including 1 or 2 sets of minor vanes and an auxiliary impeller rather than using high-pressure cleaning water in a slurry pump. However, if a fluid dynamic sealing is not designed properly, the mechanical seal is apt to be destroyed by the invading solid particle, and the slurry pump axes is worn seriously and rapidly. Though there are few empirical methods for designing a fluid dynamic sealing, the definite design concept is much deficiency. In the present work, the geometry selection of the fluid dynamic sealing for a submersible slurry pump is carried out so as to establish the basic principle for a fluid dynamic sealing design. The model pump is of centrifugal type, and has the specific speed of 136 m·m3/min·rpm. In order to validate the design concept, three dimensional turbulent flow in the pump was simulated. The total pump channel including inlet pipe, impeller with attached minor vane set, volute casing, and auxiliary impeller is treated as the calculation domain. The mesh grid is more than 2,000,000 nodes. The numerical simulation has been conducted by using a commercial code Fluent v6.1.2. To see the effect of minor vanes and auxiliary impeller geometrical parameters on the sealing performance, we change vane number, vane height, and radius of the minor vanes and auxiliary impeller, flow-rate of sealing water, etc. Based on the numerical results, a set of favorable geometrical parameters of the fluid dynamic sealing was selected for a submersible slurry pump. It is noted that the pump with the newly designed fluid dynamic sealing had been successfully applied for actual operation in the Yellow River sand transportation system in Shandong province, China.

Numerical Modelling of Turbulent Flow in Vortex Tube

2010 ◽  
Author(s):  
Hossein Khazaei ◽  
Iman Mirzaii ◽  
Ali reza Teymourtash
Keyword(s):  
Vortex Tube ◽  
Complex Structure ◽  
Small Diameter ◽  
Energy Separation ◽  
Geometrical Parameters ◽  
Turbulent Model ◽  
Cfd Model ◽  
Governing Equations ◽  
Temperature Separation ◽  
Structure Of Flow

In this paper, energy separation effect in a vortex tube has been investigated using a CFD model. The numerical simulation has been done due to the complex structure of flow. The governing equations have been solved by FLUENT™ code in 2D compressible and turbulent model. The effects of geometrical parameters have been investigated. The results have shown that the hot outlet size and its shape, does not affect the energy distribution in vortex tube and very small diameter will decrease the temperature separation.

scholarly journals THREE-DIMENSIONAL COMPUTATIONAL PREDICTION OF VORTEX SEPARATION PHENOMENON INSIDE THE RANQUE-HILSCH VORTEX TUBE

Aviation ◽  
2016 ◽  
Vol 20 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Seyed Ehsan RAFIEE ◽  
Mohammad Bagher Mohammad SADEGHIAZAD
Keyword(s):  
Turbulence Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computational Prediction ◽  
Separation Process ◽  
Counter Flow ◽  
Vortex Separation ◽  
The Impact ◽  
Air Separator

The air separators are used to provide safe, clean and appropriate air to the helicopter’s engine. In this operational study, the separation process inside a Ranque-Hilsch air separator cleaning system has been investigated to analyze the impact of choosing the appropriate turbulence model for predicting the separation process inside the air separator. This research is directed towards presenting a computational fluid dynamic explanation performed on a counter-flow air separator using air at different magnitudes of air flow fraction and applying different turbulence models. In a numerical investigation of counter-flow air separator, air has been chosen and its vortex separation phe- nomenon has been analyzed as a function of flow fraction. Furthermore, a numerical analysis to compare the outputs of a seven equation RSM turbulence model applied for the study of vortex separation of a counter-flow air separator with some two-equation turbulence methods, namely, k-ε and k-ω model as well as LES has been presented. All of the turbulence numerical methods are seen to present and predict the same flow pattern inside an air separator, but, with various details. The results show that among the tested methods the RSM creates the most accurate separation pattern. The numerical results are validated by some available experimental data with good agreement.

scholarly journals Comparison of an analytical and computational fluid-dynamics models of a commercial Ranque-Hilsch vortex tube operating with Air and Methane

2019 ◽  
Vol 9 (2) ◽  
pp. 61-71
Author(s):  
Luz Marlen Ahumada ◽  
Antonio José Bula Silvera ◽  
Kevin Andres Melendez Valencia ◽  
Julio Medina Suarez
Keyword(s):  
Analytical Model ◽  
Vortex Tube ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Preliminary Information ◽  
Industrial Implementation ◽  
Inlet Conditions ◽  
Dynamics Models

This paper presents a comparison between the behavior predicted by a computational fluid-dynamic model (CFD) and an analytical model for a commercial vortex tube using air and methane as working fluids, in addition to a three-dimensional mesh for this purpose. The numerical simulation of the turbulent, compressible and high vorticity flow was carried out using RANS equations, the Realizable k-e turbulence model and STAR-CCM+ as software for the equations solution. The variables measured in this work were temperature, pressure and velocity at the exit nozzles of the vortex generator and the tube discharges, resulting in errors of less than 16% between CFD and the analytical model. This numerical study represents a first approximation of the vorticityphenomenon and has been developed in order to establish a prototype simulation model that provides, under certain inlet conditions to the process, preliminary information on the vortex tube industrial implementation for obtaining liquefied natural gas.

Numerical Analysis of Steady Flow in Aorto-Coronary Bypass 3-D Model

1996 ◽  
Vol 118 (2) ◽  
pp. 172-179 ◽  
Author(s):  
Fabio Inzoli ◽  
Francesco Migliavacca ◽  
Giancarlo Pennati
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Intimal Hyperplasia ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Coronary Bypass ◽  
Secondary Flows ◽  
Geometrical Parameters ◽  
Shear Stresses

Intimal hyperplasia and atherosclerosis have a predominant role in the failure of coronary artery bypass procedures. Theoretical studies and in vivo observations have shown that these pathologies are much more likely to occur in the proximity of end-to-side anastomosis, thus indicating that fluid dynamic conditions may be included in the pathogenic causes of the initiation, progression and complication of intimal hyperplasia. In order to study the fluid dynamics at the anastomosis of an aorto-coronary bypass, a three-dimensional mathematical model based on a FEM approach was developed. Steady-state simulations were studied in two different geometrical models of anastomosis which differ in their insertion angles (45 and 60 degree). Flow fields with three-dimensional helical patterns, secondary flows, and shear stresses were also investigated. The results show the presence of low shear stresses on the top wall just beyond the toe of the anastomosis and in the region of the coronary artery before the junction. A high wall shear stress region is present on the lateral wall of the coronary artery immediately downstream from the anastomosis. The influence of flow rate distribution on the secondary flows is also illustrated. These results confirm the sensitivity of flow behavior to the model’s geometrical parameters and enhance the importance of reproducing the anastomosis junction as closely as possible in order to evaluate the effective shear stress distribution.

scholarly journals CFD Investigation of Vehicle’s Ventilation Systems and Analysis of ACH in Typical Airplanes, Cars, and Buses

2021 ◽  
Vol 13 (12) ◽  
pp. 6799
Author(s):  
Behrouz Pirouz ◽  
Domenico Mazzeo ◽  
Stefania Anna Palermo ◽  
Seyed Navid Naghib ◽  
Michele Turco ◽  
...  
Keyword(s):  
Energy Demand ◽  
Infection Prevention ◽  
Fluid Dynamic ◽  
Demand Management ◽  
Three Dimensional ◽  
Hvac Systems ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Cabin Environment

The simulation of the ventilation and the heating, ventilation, and air conditioning (HVAC) systems of vehicles could be used in the energy demand management of vehicles besides improving the air quality inside their cabins. Moreover, traveling by public transport during a pandemic is a concerning factor, and analysis of the vehicle’s cabin environments could demonstrate how to decrease the risk and create a safer journey for passengers. Therefore, this article presents airflow analysis, air changes per hour (ACH), and respiration aerosols’ trajectory inside three vehicles, including a typical car, bus, and airplane. In this regard, three vehicles’ cabin environment boundary conditions and the HVAC systems of the selected vehicles were determined, and three-dimensional numerical simulations were performed using computational fluid dynamic (CFD) modeling. The analysis of the airflow patterns and aerosol trajectories in the selected vehicles demonstrate the critical impact of inflow, outflow, and passenger’s locations in the cabins. The CFD model results exhibited that the lowest risk could be in the airplane and the highest in the bus because of the location of airflows and outflows. The discrete CFD model analysis determined the ACH for a typical car of about 4.3, a typical bus of about 7.5, and in a typical airplane of about 8.5, which were all less than the standard protocol of infection prevention, 12 ACH. According to the results, opening windows in the cars could decrease the aerosol loads and improve the low ACH by the HVAC systems. However, for the buses, a new design for the outflow location or an increase in the number of outflows appeared necessary. In the case of airplanes, the airflow paths were suitable, and by increasing the airflow speed, the required ACH might be achieved. Finally, in the closed (recirculating) systems, the role of filters in decreasing the risk appeared critical.

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