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computational fluid dynamics

در نشریات گروه مواد و متالورژی
تکرار جستجوی کلیدواژه computational fluid dynamics در نشریات گروه فنی و مهندسی
  • M. Ahmadi, M. Yousefifard *, H. Nowruzi
    To predict the ship's behavior in the real sea state, it is important to know its dynamic responses and added resistance in different physical and environmental conditions. Therefore, the current study employs the hybrid CFD-strip theory method to study the added resistance and dynamic responses (i.e., heave and pitch RAOs) of the DTC hull. For this purpose, different wavelengths and directions and various ship drafts and trims were considered as defined physical and environmental parameters. In addition, for the CFD approach, the finite volume method (FVM) using open source software of OpenFOAM was used, while the strip theory method was applied using Tribon. The results of the CFD and strip theory have been validated against the published experimental and numerical data, and an acceptable accordance was achieved. The obtained results indicate that an enhancement in incident wave angles increases heave and pitch RAOs. Moreover, draft change has a non-uniform effect on heave RAO, while draft reduction causes higher pitch RAO. An increase in trim by aft results in higher heave RAO. Moreover, an enhancement in trim by the bow increases the pitch RAO. Finally, the highest added resistance is achieved at the head sea for the small draft of T= 12 m and trim by bow 0.6 ° in case of wavelength equal to ship length.
    Keywords: Dynamic Response, Added Resistance, Duisburg Test Case Ship, Computational Fluid Dynamics, STRIP THEORY
  • H. Ayremlouzadeh, I. Mirzaee *, S. Jafarmadar
    A double-volute centrifugal pump plays an important role in various industries due to its enhanced hydraulic efficiency and ability to balance radial and axial forces. This study investigates the effect of discharge channel rib geometry on the hydraulic performance of a high-pressure multistage pump, installed in Goureh-Jask Oil Pipeline. These parameters include rib length, thickness, starting angle, and installation position. Computational Fluid Dynamics (CFD) simulation in real scale, were employed to analyze the impact of rib geometric parameters on the head, efficiency and mechanical power of the pump. Numerical results demonstrated a 4.43% average deviation from experimental outcomes, confirming model reliability. The findings indicated that rib design significantly affected pump performance, with different configurations excelling at various flow rates. Removing the rib increased the head, but slightly reduced efficiency due to higher radial and axial forces. Thicker ribs generally led to higher discharge head, particularly at low flow rates, while a medium thickness rib showed higher efficiency and lower mechanical power. The standard rib balanced efficiency and power consumption, while the rib with a starting angle of 45˚ performed better in high head conditions. Rib position had a moderate effect with the central rib position providing the best balance between head, efficiency, and power consumption. The results of turbulence intensity analysis revealed that considering the rib in pump discharge channel can help in reduction of turbulence and decrease the pump vibration. These outcomes provide practical insights for optimizing multistage pump designs, enhancing their efficiency and adaptability in industrial applications.
    Keywords: Centrifugal Pump, High-Pressure Multistage Pump, Pump Performance Optimization, Discharge Rib, Double-Volute Casing, Computational Fluid Dynamics
  • Eduardo Silva, Vitor Ferreira, José Cunha, Eliseu Monteiro *
    The thermal energy found in shower hot wastewater, which is usually dumped, can be recovered through heat exchangers and used to pre-heat shower cold-water, contributing to energy sustainability. The objective and novelty of this work are to present a computational fluid dynamics (CFD) model and a theoretical model based on literature correlations to evaluate the performance of a shower water horizontal heat exchanger with twisted tape inserts. CFD simulations are used to improve the shape of twisted tape in the setting of the turbulator. The findings suggest that the wastewater flow convection heat transfer coefficient is between the flow around a cylinder and the flow around a cylinder in a narrow channel. The results for the turbulator are consistent with theoretical data, except for twist ratios below 3. The most promising twisted tape design has a twist ratio of 4 and a thickness of 1 mm. A conclusion could be drawn that the efficacy of the twisted tape in the heat exchanger is greater at lower flow rates. The performance gain ranges from 18.1 % to 3.0 % for flow rates of 3–10 L/min. Future directions for this research should focus on the improvement of the external convection coefficient because it represents the highest thermal resistance in the shower wastewater horizontal heat exchanger.
    Keywords: Computational Fluid Dynamics, Convection, Energy Sustainability, Wastewater Heat Exchanger, Twisted Tape
  • مسعود دربندی*، مسعود فاضلی، داریوش رشیدی، بهنام بصیرانی، مسعود الله دادی، سید محسن حسینیان
    این مطالعه از شبیه سازی عددی برای بهبود موفقیت آمیز عملکرد یک پشته اجکتور مادون صوت استفاده می کند که برای دفع گاز دودکش در یک واحد آهن احیای مستقیم واقع در شرکت فولاد مبارکه اصفهان استفاده می شود. نرم افزار دینامیک سیالات محاسباتی توسعه یافته فعلی (CFD) از روش حجم محدود برای حل معادلات حاکم استفاده می کند که جریان آشفته تراکم ناپذیر را در پشته اجکتور نشان می دهد. این مطالعه به طور خاص بر ارزیابی تاثیر پارامترهای هندسی کلیدی، مانند طول محفظه اختلاط، طول دیفیوزر، و اجکتور نازل و زوایای دیفیوزر، بر افزایش عملکرد بدتر اجکتور متمرکز است. شبیه سازی های انجام شده نشان می دهد که طول محفظه اختلاط را نمی توان به عنوان یک پارامتر هندسی خوب برای افزایش عملکرد فعلی در نظر گرفت. به عنوان یکی دیگر از پارامترهای مهم، نشان داده شده است که طول دیفیوزر می تواند به طور قابل اعتمادی عملکرد اجکتور را افزایش دهد. برای دستیابی به عملکرد بهینه، به حدود 38 درصد افزایش در این طول نیاز دارد. با بررسی زوایای همگرایی و واگرایی نازل و دیفیوزر اجکتور به ترتیب نشان داده شده است که زوایای بهینه برای قسمت واگرایی 9/4 درجه و برای قسمت همگرایی 5/12 درجه است. در واقع، این مطالعه یک رویکرد جدید و اساسی ارائه می کند که به افراد صنعت کمک می کند تا کارایی سیستم های پشته اجکتور معیوب خود را بهبود بخشند.
    کلید واژگان: اجکتور، استک، نازل، دینامیک سیالات عددی، آنالیز حساسیت، پارامترهای هندسی
    M. Darbandi *, M. Fazeli, D. Rashidi, B. Basiriani, M. Allahdadi, S. M. Hosseinian
    This study uses the numerical simulation to successfully improve the performance of a subsonic ejector stack, which is used for the expulsion of flue gas in a Direct Reduction Iron unit located in Esfahan’s Mobarakeh Steel Company. The current extended computational fluid dynamics (CFD) software uses the finite-volume method to solve the governing equations representing the incompressible turbulent flow through the ejector stack. The study specifically focuses on evaluating the influence of key geometric parameters, such as the mixing chamber length, diffuser length, and the nozzle ejector and diffuser angles, on enhancing the deteriorated performance of the ejector. The performed simulations show that the mixing chamber length cannot be treated as a good geometry parameter to enhance the present performance. As another important parameter, it is shown that the diffuser length can reliably enhance the ejector performance. It needs about 38% increases in this length to achieve an optimum performance value. Examining the convergence and divergence angles of the nozzle and diffuser of the ejector, respectively, it is shown that the optimal angles are 4.9 degrees for the divergence part and 12.5 degrees for the convergence part. Indeed, this study provides a novel and fundamental approach, which helps the industry people to improve the efficiency of their defective ejector stack systems.
    Keywords: Ejector, Stack, Nozzle, Computational Fluid Dynamics, Sensitivity Analysis, Geometrical Parameters
  • J. Selvan, S. Manavalla *
    Air, liquid, and oil are commonly used for the cooling of electric vehicle motors. Phase change materials (PCM) are not extensively used apart from electronic components. In general, coolants like air, liquid, and oil were separately used as independent coolants for the motor. In this research, two cooling channels were added to the motor cooling. The liquid is used as a primary coolant, while PCM is used as a secondary coolant. This novel method of cooling helps to keep the bracket temperature under the allowable limit even though the liquid cooling is operating at its lowest operating point. In the study, the primary focus was on the PCM coolant channel by keeping the liquid coolant under one particular operating condition to study the PCM in detail. The thickness of the PCM had an influence on the motor cooling. Three different PCM channels were studied with thicknesses of 6 mm, 8 mm, and 10 mm. The best cases were identified with a 6 mm PCM thickness, which is better in terms of heat transfer improvement of 6% observed.
    Keywords: Electric Vehicle Motor Cooling, Phase change material, Computational Fluid Dynamics
  • Farzaneh Sajadipour, Kamran Kheiralipour *, Esmaeil Mirzaee- Ghaleh, Hekmat Rabani
    Water heaters are important tools to use solar energy, as one of the main renewable energy sources, for increasing water temperature. The present research was conducted to predict the outlet fluid temperature of a solar water heater with a flat plate collector by the computational fluid dynamics method. Initially the ambient temperature, the temperature of the inlet and outlet fluid, and the temperature of the collector were experimentally measured from 10 am to 18 pm every two hours. The fluid flow tubes of the flat plate solar collector were simulated in the ANSYS Fluent Software. The temperature of the outlet fluid was calculated based on the measured variables by the computational fluid dynamics method. For that, k-ε turbulent model was used for simulating the collector in the software. A validation was carried out between experimental data and numerical results. The results of the simulation showed that computational fluid dynamics can predict the outlet fluid temperature with errors between 1 to 22%. In most cases, the predicted temperatures were higher than those of experimented data and higher errors were observed for higher flow rates.
    Keywords: Solar energy, Flat plate solar collector, Computational Fluid Dynamics, Fluid temperature
  • H. Safikhani *, E. Jabbari, M. Yousefi, V. Tahmsbi
    Studies have shown that most of the particles sprayed on emergency respirational patients, accumulate inside the endotracheal tube and its connector. In this paper, applying Computational Fluid Dynamics (CFD) and Response Surface Method (RSM), an optimized geometry is introduced for higher efficiency of the drug delivery for patients with emergency respiratory diseases. In CFD modeling, finite volume method and for two-phase flow modeling, Lagrangian method is used. Reynolds averaged Navier–Stokes equations with Reynolds stress turbulence model are solved using SIMPLE pressure correction algorithm within the computational domain. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). For optimization process, six different parameters including three dimensions of the connector of the tube: connector length, connector diameter and injection diameter, injection velocity of the drug particles, air flow velocity and particle size are investigated. Using Design of Experiments (DOE) and RSM, the output efficiency of the model and second-order regression equation model are derived and accuracy of the model is confirmed. Then the effect of each input parameter on the efficiency is investigated. Dringer algorithm is applied to optimize the process and the best combination of input parameters yielding the highest efficiency is introduced.
    Keywords: Computational Fluid Dynamics, Drug Delivery Device, Endotracheal tube, optimization, Respirational Patients, response surface method
  • H. Safikhani *, H. Shaabani
    Frost formation is a renowned phenomenon in HVAC, aeronautical and refrigeration industries. In this paper, numerical modeling and parametric study of the frost formation in the interrupted Micro Channels Heat sinks (MCHS) is investigated considering microfluidic effects in slip flow regime. For numerical modeling, basic equations of humid air and frost including continuum, momentum, energy and phase change mechanism are numerically solved and results are compared with reported data. Knudsen number (Kn) is changed so that slip flow regime requirement is accomplished. This requirement is also considered for setting boundary conditions. The effect of different parameters like cold surface temperature, time and Kn are studied on the frost formation and details of the flow field. Results revealed that with an increase in time and a decrease in Kn and cold surface temperature, weight and thickness of the frost increase. Moreover, with thicker frost maximum flow velocity rises in the microchannel. The details of frost formation and flow field, revealed by the numerical results can remarkably assist designing interrupted microchannel.
    Keywords: Micro Channels Heat sinks, Microchannel, Frost Formation, Computational Fluid Dynamics, Slip Regime, microfluidic
  • E. Fatahian, H. Salarian, H. Fatahian *
    In the present study, an attempt has been made to use Computational Fluid Dynamics (CFD) in the assessment of hazardous gas dispersion over obstacles. For this aim, the accidental dispersion of hazardous gas from the hole and the effect of different parameters such as changes in inlet wind velocity, the direction of the pollutant cloud and its movement, mass fraction of gas dispersion, and the pressure distribution were numerically analyzed. The flow was assumed as three-dimensional, unsteady, turbulent, and compressible. Different turbulent models were used in modeling the gas release and the most accurate one was suggested. The numerical simulation demonstrated that the gas mass fraction increased significantly due to the sudden dispersion of the gas. The amount of gas concentration gradually decreased after the formation of pollutant clouds by moving in the horizontal direction. Moreover, gas mass fraction had decreased by increasing the height. Comparing the results revealed that the pollutant cloud did not cover the surrounding area in the wind velocity of 1 m/s. Therefore, the pollutant clouds generated in this case could not impose a threat. In higher wind velocities (3 m/s and 5 m/s), the pollutant cloud approximately covered the surrounding areas, which caused a severe threat. The maximum overpressure at the hole is 5.7 Pa for a wind velocity of 5 m/s, while the maximum negative pressure was about -7.1 Pa. The influencing radius was obtained about 9.3 m. The overpressure did not cause obvious damage to buildings but led to a slight hurt to humans.
    Keywords: Gas Dispersion, Computational Fluid Dynamics, Mass Fraction, Obstacles, Turbulence
  • محمدعلی حسن زاده*، محمود حبیبیان

    آمونیوم پر کلرات که یکی از اکسیدکننده اصلی در بسیاری از پیشرانه های جامد به شمار می رود. این نوع بلور به صورت عمده از طریق بلورسازی تولید می شود. در این تحقیق هیدرودینامیک جریان در بلورساز DTB [1] با استفاده از نرم افزار Ansys Fluent به منظور بدست آوردن دیدی جامع از الگوی جریان بلورساز که تاثیر به سزایی بر روی توزیع اندازه ذرات بلور دارد، بررسی شده است. مشخصات هیدرودینامیک در بخش های مختلف بلورساز بررسی شده است. نتایج حاصل از شبیه سازی نشان داد که در فضای داخلی لوله مکش، جریان بالارونده بوده و بیشترین تلاطم و سرعت محوری جهت رساندن خوراک تازه به سطح جوشش وجود دارد. بیشترین هسته زایی در منطقه جوشش به دلیل فوق اشباعیت بالا و تنش برشی جریان اتفاق می افتد. هسته های تشکیل شده در منطقه عرضی بین لوله مکش و بفل در حضور جریان یکنواخت پایین رونده و سرعت کمتر نسبت به داخل لوله مکش، رشد می کنند. در منطقه دسته بندی (منطقه عرضی بین بفل و دیواره بلورساز)، جریان بسیار آهسته و عاری از هرگونه تلاطم به سمت بالا بوده و درنتیجه بهترین منطقه جهت دسته بندی ذرات به شمار رفته و ذرات درشت تر به دلیل نیروی گرانش در این منطقه جداسازی می شوند.

    کلید واژگان: بلور آمونیموم پرکلارت، دینامیک سیالات محاسباتی- بلورساز (DTB) - هیدرودینامیک، هسته زایی، رشد هسته
    M. A. Hasanzadeh*, M. Habibian

    The ammonium perchlorate (AP) is one of the useful oxidizer for making solid fuels, which is mainly produced by crystallization. In this study, the hydrodynamics of DTB crystallizer was simulated using Ansys Fluent in order to achieve a good understanding of flow pattern inside crystallizer which affects the CSD of AP. The hydrodynamic characteristics of crystallizer were studied for different sections of the crystallizer. The results showed that the upward flow inside the tube pushes the fresh feed to the boiling zone. Nucleation occurs in the boiling zone due to high saturation and shear stress of stream. The formed nuclei grow in the cross-section region between the tube and baffle in the presence of uniform downstream flow. In the classification region, the upward flow is uniform and slow enough to classify the crystals. Hence, this region is the best area to classify particles separated by the gravitational force.

    Keywords: Ammonium Perchlorate, Computational Fluid Dynamics, DTB Crystallizer, Hydrodynamics, Nucleation, Crystal Growth
  • Iman Eslami Afrooz *, Dennis Ling Chuan Ching
    The main advantage of a fluidized bed is its capability in excellent gas-fuel mixing. However, due to the lacks of gas radial momentum, its lateral mixing of gas-solid is not adequate. Therefore, this research is focused on fluidized bed hydrodynamics enhancement using the modified gas distributor plate design. For getting an optimum fluidized bed hydrodynamics prediction, three different classical ANSYS Fluent drag models, namely Wen-Yu, Syamlal O’Brien, and Gidaspow are examined first. Afterward, a novel distributor plate called swirl distributor plate (SDP) is proposed in order to enhance the gas-fuel mixing in vertical and radial directions. In terms of simulation approach, results were presented and compared with the experimental data. It has been observed that better hydrodynamics prediction is achieved by Syamlal O’Brien drag model. The effect of SDP on gas-solid mixing was then studied numerically and compared with conventional distributor plate (CDP). Compared with CDP, better gas-solid mixing was found while the SDP was used. As a final point, gasification test was conducted in a lab scale system in order to study and compare the composition of produced syngas using both distributor plates. Based on the gasification results, SDP leads to promotion of Hydrogen and Carbon monoxide by 34.85 and 65.92 percent, respectively.
    Keywords: Distributor plate, fluidized bed, Gas-solid mixing, Hydrodynamics, Computational Fluid Dynamics
  • Rehan Khan *
    Erosion caused by sand transportation in flow changing devices is a serious concern in the hydrocarbon and mineral processing industry, which entail to failure and malfunction of flow devices. In this study, computational fluid dynamics (CFD) with discrete phase models (DPM) were employed for analysis of carbon steel long radius 90-Degree elbow erosion due to the sand concentration of 2, 5 and 10% transported in the liquid phase. The simulation is completed with the Reynolds Stress Model (RSM) and Oka erosion model. The simulation result from the RSM model was validated by comparison with the erosion distribution results in the literature. The largest erosion zones have been identified at or near the outlet of the 90-Degree elbows outer wall surface with a maximum erosion rate appeared for 10% sand concentration. Furthermore, the relationships of turbulence intensity on erosion, particle trajectory, and particle mass concentration in the elbow pipe were discussed.
    Keywords: Erosion, Long radius elbow, discrete phase model, Computational Fluid Dynamics, Sand Concentration
  • Haleh Sadeghi, Iraj Mirzaei, Shahram Khalilaria, Sajad Rezazadeh *, Mojtaba Rasouli Gareveran
    Among the renewable energy systems, fuel cells are of special significance about which more investigation is required. The principal goal of the present study is considering the effect of the geometry change on the fuel cell's performance. In this paper, a three-dimensional model of proton exchange membrane fuel cell has been numerically simulated with conventional cubic geometry. Afterwards, two brand-new cylindrical models have been proposed to compare and select the best model. The governing equations include mass, momentum, energy, species and electrical potential, which are discretized and solved using the method of computational fluid dynamics. The results obtained from numerical analyses were validated with those from experimental data, which showed acceptable agreement. For the above-mentioned models, changes in the species mass fraction, temperature, electric current density, and over-potential were analyzed in more detail. The results reveal that, in all three models, by decreasing the amount of cell voltage differences between the anode and the cathode, higher current density is produced, which leads to high input species consumption and, consequently, more water and heat generation. On the other hand, the four-channel cylindrical model is more efficient than the other two models and has shower pressure drop due to its shorter pathway. The results illustrated that, at V=0.6 )V(, the amount of the output current density in the four-channel model increased by approximately 18.4 %, compared to that in the other two models. Further, in this model, the material used in bipolar plates is less than that in the other models.
    Keywords: Computational Fluid Dynamics, Fuel Cell, Electrical current density, Membrane, Geometry
  • B. Srusti, M. B. Shyam Kumar *
    In this work both experimental and numerical analysis are carried out to investigate the effect of solar radiation on the cabin air temperature of Maruti Suzuki Celerio car parked for 90 min under solar load condition. The experimental and numerical analysis encompasses on temperature increment of air at various locations inside the vehicle cabin. The effect of 90 min exposure to the environment is simulated with the help of Discrete Ordinance (DO) and Surface to Surface (S2S) radiation models using ANSYS FLUENT 18.2. Moreover, the impacts of using different turbulence model on the accuracy of the simulation results and the comparison between steady state and transient state simulation results have also been studied. The results of the simulation are compared with the experimental data to contrast the model. The absolute average deviation in temperature predicted by DO and S2S model from the experimental data are 10.07 and 10.01%, respectively. In this work both experimental and numerical analysis are carried out to investigate the effect of solar radiation on the cabin air temperature of Maruti Suzuki Celerio car parked for 90 min under solar load condition. The experimental and numerical analysis encompasses on temperature increment of air at various locations inside the vehicle cabin. The effect of 90 min exposure to the environment is simulated with the help of Discrete Ordinance (DO) and Surface to Surface (S2S) radiation models using ANSYS FLUENT 18.2. Moreover, the impacts of using different turbulence model on the accuracy of the simulation results and the comparison between steady state and transient state simulation results have also been studied. The results of the simulation are compared with the experimental data to contrast the model. The absolute average deviation in temperature predicted by DO and S2S model from the experimental data are 10.07 and 10.01%, respectively.
    Keywords: Solar Radiation, Car Cabin Temperature, Computational Fluid Dynamics, Discrete Ordinance Radiation Model, Surface to Surface Radiation Model
  • A. Meysami *, H.I. Rahimzadeh, R. Amini Najafabadi, T. Dallali Isfahani
    Steel pipes with circular cross-sections are usually used in cooling panels of electric arc furnaces. In the present study pipes with square cross-sections under equivalent conditions were used to obtain more information on the possibility of increasing the heat transfer and cooling efficiency. The results showed increased efficiency of the square pipe compared to the circular cross-section pipes. This increase led to an increase in the cooling power and life expectancy under similar conditions. The fluid flow field and heat transfer were obtained using simulation. A comparison of the heat transfer and the energy of the circular and square cross-sections showed that the square cross-sections had a higher rate of heat transfer and work efficiency.
    Keywords: Pipe, Arc furnace, Radiator, computational fluid dynamics
  • S. T. G. Krishna Teja, C. P. Karthikeyan, M. B. Shyam Kumar*
    The objective of this study is to design and analyse materials which are capable of harvesting water from thin air using condensation phenomenon which employs the radiative cooling approach. These passive cooling materials not only solve the water generating problems, but also employed in various cooling applications. The fundamental concept of radiative cooling is analysed and the performance parameters were identified to test the passive cooling ability of the designed material for water harvesting. The field of Photonics is studied which has the potential to obtain the surface temperature significantly lower than the atmospheric temperature by radiation phenomenon. Important parameters are identified to validate the performance of the proposed materials. ANSYS FLUENT is used to analyse the surface temperature for the given boundary conditions and the potential material which is capable of obtaining a significant temperature difference with respect to the ambient temperature is identified. A sandwich material is designed and its performance is evaluated using Computational Fluid Dynamics (CFD) by which we could achieve temperature difference of 15°C. To reduce the heat gain losses by conduction and convection, we designed a physical system which could maintain significant temperature difference even in the broad day-sunlight. CFD analysis of the designed system under similar boundary conditions gave satisfying results of maintaining the temperature difference of about 15°C for a prolonged period of time due to minimal heat gain losses. Later, two potential materials are manufactured and the performance parameters of these materials are characterized using U-V/Vis (Ultraviolet-Visible) and FTIR (Fourier Transform Infrared) Spectroscopy experiments. The results of absorption phenomenon in the U-V/Vis spectrum and the transmittance phenomenon in the FTIR spectrum of the two materials explain the reason for the passive cooling ability of materials.
    Keywords: Radiative cooling, Computational Fluid Dynamics, Photonic Material, Pigmented Foil, UV, Visible, Fourier Transform Infrared
  • A. Toloei*, H. Ramezi
    The purpose of this paper is to analyze the flow field structure in transient state and performance of secondary injection system for thrust vectoring in divergent section of a two-dimensional nozzle. Secondary injection for thrust vectoring in a two-dimensional nozzle is studied by solving three-dimensional Reynolds-averaged equations by means of fluent solver. Spalart-Allmaras model was used to model the fluid behavior near the walls. Density-based solver and explicit formulation are employed in the computational model. Results show that the solution of interfered field in the transient-state is more accurate than steady-state, especially in the initial injection. In addition, various testing showed that the maximum side force would be in the injection angle of twenty degrees and with increasing pressure ratio, we have more side force. At the end it was observed that by sketching the exit gases deviation according to time, we could be informed of desired secondary injection time in order to achieve required deviation around pitch axis, and the required force to achieve desired deviation angle. The innovation of this paper is the solution of interfered field in transient state, and of course the injection from the optimal point.
    Keywords: Fluid Mechanics, Flow Field, Computational Fluid Dynamics, Secondary Injection, Thrust Vector Control, Injection Angle, Nozzle
  • R. Davarnejad*, M. Kheiri
    Turbulent heat transfer in Helically Corrugated tubes (HCT) was numerically investigated for pure water and SiO2 nanofluid using Computational fluid dynamics (CFD). This study was carried out for different corrugating pitches (5, 7, 8 mm) and heights (0.5, 0.75, 1.25 mm) at various Reynolds numbers ranging from 5000 to 13300. The effect of nanoparticles on heat transfer augmentation for plain tube and HCT was considered and the relative Nusselt numbers were also compared. However, the heat transfer extremely increased with increasing the volume fraction of nanoparticles in the plain tube but, the effect of helical corrugation on the heat transfer increment was much more than that of the nanoparticles enhancement in the HCT. It was concluded that the corrugated height increment and the corrugated pitch reduction increase the heat transfer process. The maximum heat transfer was obtained at Reynolds number of 13300, HTC with p=5 mm and e=1.25 mm, and SiO2 volume fraction of 1%.
    Keywords: Computational Fluid Dynamics, Helically Corrugated Tubes, Plain Tube, Turbulent Heat Transfer
  • Y. Vazifeshenas, M. Farhadi*, K. Sedighi, R. Shafaghat
    The purpose of this study is to investigate the performance and three-dimensional behavior of the flow in a mixed flow pump and the way cavitation phenomenon is affected by different parameters such as fluid temperature, pump speed and flow rate. Computational fluid dynamic software FLUENT was utilized to simulate the whole flow field of the pump. RNG k-ε model combined with standard wall functions is chosen to deal with the turbulent feature of the problem. The studied pump has four blades mounted on a conical hub which form the rotary part and nine static vanes afterward as the stationary part. So the rotor-stator interaction was treated with a Multiple Reference Frame (MRF) technique. The flow rates and pump speed were the key parameters for investigation. While the flow rates variation and the pump revolution change cavitation occurrence widely, the temperature variations caused by weather changes during a year has little effect on cavitation. The cavitation region which is defined by the saturation pressure in that temperature was shown for various cases on a blade.
    Keywords: Mixed, flow pump, Multiple Reference Frame, Computational fluid dynamics, Cavitation
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  • نتایج بر اساس تاریخ انتشار مرتب شده‌اند.
  • کلیدواژه مورد نظر شما تنها در فیلد کلیدواژگان مقالات جستجو شده‌است. به منظور حذف نتایج غیر مرتبط، جستجو تنها در مقالات مجلاتی انجام شده که با مجله ماخذ هم موضوع هستند.
  • در صورتی که می‌خواهید جستجو را در همه موضوعات و با شرایط دیگر تکرار کنید به صفحه جستجوی پیشرفته مجلات مراجعه کنید.
درخواست پشتیبانی - گزارش اشکال