scholarly journals Speed distribution in the exhaust diffuser of the air fan

2022 ◽  
Vol 354 ◽  
pp. 00027
Author(s):  
Ion Gherghe ◽  
Doru Cioclea ◽  
Florin Rădoi ◽  
Emeric Chiuzan ◽  
Răzvan Drăgoescu
Keyword(s):  
Field Distribution ◽  
Dynamic Pressure ◽  
Axial Fan ◽  
Entire Surface ◽  
Circular Duct ◽  
Speed Distribution ◽  
Air Inlet ◽  
Developed Pressure ◽  
Made In ◽  
Air Discharge

A perfect connection between the column and the fan is that which ensures an air inlet in the fan, evenly distributed, over the entire surface of the suction mouth and an air outlet from the fan outlet made in a way that allows the full use of developed pressure. For both suction and exhaust, fans must be equipped with a device/diffuser. When the fan discharges freely into the atmosphere without any connection, a loss equivalent to 50% of the average dynamic pressure at the discharge port occurs. If the fan discharges into a speaker, the loss depends on its angle. At a peak angle of 30° corresponds to a loss of ≈ 25% of the average dynamic pressure in the discharge mouth, and to reduce air vortices the speakers must be built at an angle of inclination to vertical or horizontal between 12- 15°, in order to reduce the aerodynamic resistances. The paper will present the speed field distribution of an axial fan located on a circular duct, provided on the air discharge side with a diffuser with a length of 1.5 m, at an angle of inclination to the vertical or horizontal of 12°.

Solar wind proton precipitation to the surface of Mercury

2020 ◽  
Author(s):  
Shahab Fatemi ◽  
Andrew R. Poppe ◽  
Stas Barabash
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Plasma ◽  
Solar Wind Dynamic Pressure ◽  
Solar Wind Proton ◽  
Entire Surface ◽  
The North ◽  
Proton Precipitation ◽  
Neutral Sodium ◽  
The Imf

<p>We examine the effects of the interplanetary magnetic field (IMF) orientation and solar wind dynamic pressure on the solar wind proton precipitation to the surface of Mercury. We use the Amitis model, a three-dimensional GPU-based hybrid model of plasma (particle ions and fluid electrons), and explain a method we found necessary to accurately calculate plasma precipitation to the surface of Mercury through the highly dynamic Hermean magnetosphere. We use our model to explain ground-based telescope observations of Mercury's neutral sodium exosphere, and compare our simulation results with MESSENGER observations. For the typical solar wind dynamic pressure near the orbit of Mercury (i.e., ~7-8 nPa) our model shows a high solar wind proton flux precipitates through the magnetospheric cusps to the high latitudes on both hemispheres on the dayside with a higher precipitation rate to the southern hemisphere compared to the north, which is associated with the northward displacement of Mercury's intrinsic magnetic dipole. We show that this two peak pattern, which is also a common feature observed for neutral sodium exosphere, is controlled by the radial component (B<sub>x</sub>) of the IMF and not the B<sub>z</sub> component. Our model also suggests that the southward IMF and its associated magnetic reconnection do not play a major role in controlling plasma precipitation to the surface of Mercury through the magnetospheric cusps, in agreement with MESSENGER observations that show that, unlike the Earth, there is almost no dependence between the IMF angle and magnetic reconnection rate at Mercury. For the typical solar wind dynamic pressure, our model suggests that the solar wind proton precipitation through the cusps is longitudinally centered near noon with ~11<sup>o</sup> latitudinal extent in the north and ~21<sup>o</sup> latitudinal extent in the south, which is consistent with MESSENGER observations. We found an anti-correlation in the incidence area on the surface and the incidence particle rate between the northern and southern cusp precipitation such that the total area and the total rate through both of the cusps remain constant and independent of the IMF orientation. We also show that the solar wind proton incidence rate to the entire surface of Mercury is higher when the IMF has a northward component and nearly half of the incidence flux impacts the low latitudes on the nightside. During extreme solar events (e.g., Coronal Mass Ejections) a large area on the dayside surface of Mercury is exposed to the solar wind plasma, especially in the southern hemisphere. Our model suggests that over 70 nPa solar wind dynamic pressure is required for the entire surface of Mercury to be exposed to the solar wind plasma.</p>

scholarly journals Improvement of the Chimney Effect in Stack Ventilation

2021 ◽  
Vol 11 (19) ◽  
pp. 9185
Author(s):  
Romana Antczak-Jarząbska ◽  
Krzysztof Pawłowski ◽  
Maciej Niedostatkiewicz
Keyword(s):  
Natural Ventilation ◽  
Ventilation System ◽  
Common Denominator ◽  
Air Inlet ◽  
Transparent Barrier ◽  
Scale Experiment ◽  
Stack Ventilation ◽  
Chimney Effect ◽  
Rotary Type ◽  
Made In

The article is focused on the airflow in a ventilation system in a building. The work examines the methods which enhance the chimney effect. In this paper, three cases with different chimneys were analyzed for the full-scale experiment. These cases were characterized by different geometrical and material parameters, leading to differences in the intensity of the ventilation airflow. The common denominator of the cases was the room with the air inlet and outlet to the ventilation system. The differences between the experimental cases concerned the chimney canal itself, and more precisely its part protruding above the roof slope. The first experimental case concerned a ventilation canal made in a traditional way, from solid ceramic brick. The second experimental case concerned the part that led out above the roof slope with a transparent barrier, called a solar chimney. In the third experimental case, a rotary type of chimney cap was installed on the chimney to improve the efficiency of stack ventilation. All these cases were used to determine the performance of natural ventilation—Air Change per Hour (CH). Additionally, the paper presents a technical and economic comparison of the solutions used.

scholarly journals Alat Pengumpul Kopi Model Terhampar Secara Otomatis Berbasis Arduino Uno

Electrician ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Deka Perlanda ◽  
Syaiful Alam ◽  
Sri Purwiyanti
Keyword(s):  
Mechanical System ◽  
Open Field ◽  
Direct Sunlight ◽  
Entire Surface ◽  
Additional Load ◽  
The World ◽  
Actuator System ◽  
Arduino Uno ◽  
Time And Energy ◽  
Made In

Intisari— Dalam dunia engineering, suatu sistem direkayasa menjadi serba otomatis. Salah satunya pada alat bantu pekerjaan, yaitu untuk mempermudah dan mengefisienkan waktu serta tenaga yang digunakan. Jenis alat bantu pekerjaan yang direkayasa tersebut adalah alat pada proses pengumpulan kopi. Untuk menghasilkan kopi yang terbaik maka proses pengolahan kopi harus dilakukan secara benar. Kopi dijemur di lapangan terbuka dibawah terik matahari langsung. Para petani pun kesulitan saat mengumpulkan kopi yang masih terhampar di lapangan dan apabila mendadak cuaca sudah mulai mendung dan hujan turun. Sehingga tercetuslah ide untuk membuat “Rancang Bangun Alat Pengumpul Kopi Model Terhampar Secara Otomatis Berbasis Arduino UNO”. Rancangan bangun alat ini merupakan miniatur yang dibuat pada bidang agroindustri kopi yang berukuran 60x90 cm. Alat ini bekerja apabila sensor LDR mendeteksi cuaca gelap dan Arduino UNO akan mengendalikan motor DC untuk menggerakan sistem mekanikal/aktuator. Kemudian, sistem mekanikal tersebut akan menggerakkan dua buah papan pengumpul yang bergerak dari dua arah yang berbeda dan menarik kopi dari pinggir lapangan menuju ke tengah lapangan. Pada saat proses pengumpulan kopi sedang dilakukan dan hujan tiba-tiba turun, maka terpal otomatis akan menutupi seluruh permukaan lapangan untuk mencegah kopi agar tidak basah, berdasarkan respon yang diterima oleh sensor hujan. Kopi yang selesai dikumpulkan akan menggunung dibagian tengah lapangan dan alat akan berhenti bekerja Berdasarkan hasil pengamatan yang dilakukan, intensitas cahaya yang dibaca oleh sensor sangat mempengaruhi cara kerja alat ini. Saat cuaca terang dengan intensitas cahaya sebesar 286 Lux alat tidak akan bekerja, dan aktif pada saat intensitas dibawah 68 Lux. Sedangkan untuk sistem aktuator, semakin besar torsi pada motor maka akan semakin besar pula arus yang terukur. Sehingga membutuhkan daya yang lebih besar pula. Terlihat pada saat proses pengumpulan kopi berlangsung arus yang terukur mencapai 1,1 ampere dan torsi yang terukur mencapai 3,5 N/m. Maka diperlukan perancangan yang baik pada sistem mekanikal agar tidak terjadi kesalahan yang bisa menyebabkan penambahan beban pada motor. Kata kunci: Arduino, mechanical, mikrokontroller, otomatis, rekayasa, dan sistem elektrik.  Abstract— In the world of engineering, a system is engineered to be completely automated. One of them on the work aids, namely to simplify and streamline the time and energy used. The types of work tools that are engineered are tools in the process of collecting coffee. To produce the best coffee then the coffee processing must be done correctly. Coffee is dried in an open field under direct sunlight. The farmers were defeated when collecting coffee that still lies in the field and when suddenly the weather has started cloudy and rain down. So the idea came out to make the Design of Arduino UNO Model-Based Automatic Collecting Apparatus. The design of this tool is a miniature made in the field of coffee agro-industry measuring 60x90 cm. This tool works when the LDR sensor detects dark weather and Arduino UNO will control the DC motor to drive the mechanical / actuator system. Then, the mechanical system will move two collecting boards moving from two different directions and pull the coffee from the sidelines to the center of the field. At the time the coffee collection process is being done and the rain suddenly goes down, the automatic tarp will cover the entire surface of the field to prevent the coffee from getting wet, based on the response received by the rain sensor. The finished coffee will be mounted in the center of the field and the equipment will stop working. Based on observations made, the intensity of light read by LDR sensors greatly affect the workings of this tool. When the weather is bright with the intensity of 286 Lux the appliance will not work and is active at the intensity below 68 Lux. As for the actuator system, the greater the torque on the motor will be the greater the measured current. So it requires more power as well. Seen at the time of the process of collecting the current measured currents reached 1.1 ampere and torque measured to reach 3.5 N / m. It is necessary to design a good mechanical system to avoid errors that can cause additional load on the motor. Keywords: Arduino UNO, automatic, electrical, engineering, mechanical systems, microcontroller, and syntax.

scholarly journals Effect of Two- and Three-Dimensionally Designed Guide Vanes with Different Camber Length on Static Pressure Recovery of a Wall-Mounted Axial Fan

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1595
Author(s):  
Yong-In Kim ◽  
Yong-Uk Choi ◽  
Cherl-Young Jeong ◽  
Kyoung-Yong Lee ◽  
Young-Seok Choi
Keyword(s):  
Flow Rate ◽  
Guide Vane ◽  
Dynamic Pressure ◽  
Pressure Rise ◽  
Design Flow ◽  
Low Flow ◽  
Axial Fan ◽  
Flow Angle ◽  
Numerical Effort ◽  
Vane Angle

This study was based on a numerical effort to use the motor support (prop) as a guide vane when the motor of a wall-mounted axial fan was located at the fan outlet while maintaining the structural and spatial advantage. The design for the guide vane followed two- and three-dimensional methods. The inlet vane angle, meridional length (total), and meridional length with a vane angle of zero (0) degrees (linear) were considered as design variables. At the design and some low flow rate points, the 2D design offered the most favorable performance when the meridional length with a vane angle of zero (0) degrees (linear) was 30% based on total length, and was the worst for 70%. The 3D design method applied in this study did not outperform the 2D design. In the 2D design concept, averaging the flow angle for the entire span at the design flow rate could ensure a better pressure rise over a more comprehensive flow rate range than weighting the flow angle for a specific span. In addition, the numerical results were validated through an experimental test, with an important discussion of the swirl (dynamic pressure) component. The influence of the inlet motor and turbulence model are presented as a previous confirmation.

Steam Explosion Experiments Using ZrO2 and ZrO2/UO2 Mixture

2002 ◽  
Author(s):  
Jinho Song ◽  
Ikkyu Park ◽  
Yongseung Sin ◽  
Jonghwan Kim ◽  
Seongwan Hong ◽  
...  
Keyword(s):  
Steam Explosion ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Pressure Profile ◽  
Conversion Ratio ◽  
Water Pool ◽  
Energy Research ◽  
Melt Temperature ◽  
Water Interaction ◽  
Made In

Korea Atomic Energy Research Institute (KAERI) has been carrying an experimental research program on the steam explosion named “Test for Real cOrium Interaction with water (TROI)” since 1997. The objective of the program is to investigate whether the corium would lead to an energetic steam explosion and to measure the conversion ratio of the energetic steam explosion. In the first series of tests using several kg of ZrO2 where the melt/water interaction were made in the water pool at 30 ∼ 95 °C, either a quenching or a spontaneous steam explosions was observed. In the second series of tests using the mixture of UO2/ZrO2 performed in a similar manner as that of ZrO2, it also resulted in either a quenching or energetic steam explosion. The morphology of debris and pressure profile clearly indicate the differences in those two phenomena. The process parameters including the dynamic pressure, dynamic impulse, water and melt temperature, static pressure inside the containment chamber were measured.

Measurement of Laminar Burning Speeds and Determination of Onset of Auto-Ignition of Jet-A/Air and Jet Propellant-8/Air Mixtures in a Constant Volume Spherical Chamber

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Ali Moghaddas ◽  
Casey Bennett ◽  
Kian Eisazadeh-Far ◽  
Hameed Metghalchi
Keyword(s):  
High Pressures ◽  
Dynamic Pressure ◽  
Combustion Process ◽  
Pressure Rise ◽  
Constant Volume ◽  
Pressure Data ◽  
Spherical Vessel ◽  
Auto Ignition ◽  
Made In

The laminar burning speeds of Jet-A/air and three different samples of jet propellant (JP-8)/air mixtures have been measured and the onset of auto-ignition in JP-8/air premixed mixtures has been determined. The experiments were made in a constant volume spherical vessel, which can withstand high pressures up to 400 atm. Burning speed was calculated from dynamic pressure rise due to the combustion process in the vessel. A thermodynamic model based on the pressure rise was used to determine the burning speed. The burning speeds were measured in lean mixtures for pressures of 1–4.5 atm and temperatures of 493–700 K. The onset of auto-ignition of JP-8 fuels was evaluated by observing intense fluctuations of pressure data during the explosion of the unburned gas. It was revealed that Jet-A and JP-8 have very similar burning speeds; however, auto-ignition temperatures of various samples of JP-8 were slightly different from each other. Auto-ignition of these fuels was much more sensitive to temperature rather than pressure.

A Stagnation Pressure Probe for Supersonic and Subsonic Flows

1974 ◽  
Vol 25 (2) ◽  
pp. 91-100 ◽  
Author(s):  
M J Goodyer
Keyword(s):  
Mach Number ◽  
Dynamic Pressure ◽  
Flow Property ◽  
Stagnation Pressure ◽  
Pressure Probe ◽  
Number Range ◽  
Subsonic Flows ◽  
Permissible Range ◽  
Free Stream Mach Number ◽  
Made In

SummaryThe usefulness of a probe which can sense the absolute value of the stagnation pressure in supersonic flow has long been recognised. In the past such a probe has not been available and therefore it has been necessary to infer this fundamentally important flow property from measurements of other properties. This paper describes a probe which has been developed specifically to measure accurately the stagnation pressure of a supersonic gas stream. Measurements of the performance of the probe to date show that it is capable of measuring absolute stagnation pressure with an accuracy of 0.1 per cent in the Mach number range 1.5 to 2.1. No measurements have yet been made in the transonic range, but at low subsonic speeds the probe has demonstrated its ability to measure dynamic pressure within an accuracy of 0.1 per cent at a Mach number of approximately 0.13. The permissible range of misalignment in pitch and yaw before the pressure recovery begins to deteriorate are functions of free-stream Mach number and are usefully wide.

Fixed Vane Stator Development for Axial Fan Performance Improvement in Electronics Cooling

2007 ◽  
Author(s):  
Gavin D. Stanley
Keyword(s):  
Design Of Experiments ◽  
Acoustic Noise ◽  
Dynamic Pressure ◽  
Electronics Cooling ◽  
Leading Edge ◽  
Cfd Modeling ◽  
Axial Fan ◽  
Development Method ◽  
Stator Vane ◽  
Axial Fans

An analysis and development method for augmenting flow and pressure performance of electronic cooling axial fans using a fixed vane stator is established using classical hand calculations, 2-dimensional (2D) Computational Fluid Dynamics (CFD) analysis, data from a design of experiments, and 3-dimensional (3D) CFD modeling. Where the size of electronic enclosures may disallow an increase in diameter of axial fans but allow for an increase in depth; a fixed vane stator is implemented to recapture lost dynamic pressure associated with swirl and radial flow vectors from the axial fan blades thus augmenting the pressure/flow curve of the unit. Stator blade effectiveness is evaluated and optimized first using data associated with National Advisory Committee for Aeronautics (NACA) airfoil shapes and then using 2-dimensional (2D) CFD analyses on both the impeller and stator blades. CFD modeling approaches and solving methods are discussed. A Design of Experiments (DOE) is utilized to verify and optimize the performance of the stator vanes and identifies the effectiveness of the stator vane angle, curvature of the stator leading edge, and number of stator vanes. At a constant back pressure the best performing DOE geometry delivered a 22% improvement in flow at constant electrical power input and a 41% improvement in flow at constant acoustic noise. This result was confirmed using a 3D CFD modeling. This analysis and development method provides a good baseline for evaluating and choosing proper stator vane geometries for flow improvement in axial fans.

Radial Mode Analysis of Broadband Noise in Flow Ducts Using Azimuthal Sensor Array

2017 ◽  
Author(s):  
Kunbo Xu ◽  
Weiyang Qiao ◽  
Fan Tong ◽  
Renke Wei
Keyword(s):  
Sensor Arrays ◽  
Sound Field ◽  
Broadband Noise ◽  
Power Measurement ◽  
Mode Analysis ◽  
Sound Power ◽  
Sound Waves ◽  
Axial Fan ◽  
Circular Duct ◽  
Broadband Sound

For the evaluation and improvement of fan noise reduction notions and the verification of broadband sound power measurement in flow ducts, special interest was given to the analysis of the broadband noise fields in duct. Two axial sensor arrays were wall-flush mounted upstream of a single-stage axial fan in the circular duct section of the fan inlet, staggered by 180° in the circumferential direction. During the tests, the rotating drum was rotated by step of 6 degrees to give a total 840 measurement points. There are two static reference microphones mounted upstream of rotating measurement section. Time-series of 12 seconds duration were recorded at each of the 30 azimuthal positions of the rotating duct in order to allow for a statistically accurate cross-correlation data analysis. This method is able to discriminate the sound waves propagating in upstream and downstream directions. Special attention was given to the blade passing frequencies of the axial fan. Rotor-stator interaction mode dominates the incident sound field, while modes with low azimuthal order play an important role in the reflected sound field. The reflected broadband sound power is almost 10dB lower than the transmitted sound field in a broad-frequency range. On the whole, this method behaves robustly in decomposition of broadband noise in flow duct and delivers physically meaningful broadband mode amplitudes.

An Evaluation of Simulated Flow and Experimental Study Through an Axial Fan

2003 ◽  
Author(s):  
J. Xie ◽  
R. S. Amano ◽  
E. K. Lee
Keyword(s):  
Experimental Study ◽  
Cfd Simulation ◽  
Dynamic Pressure ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Axial Fan ◽  
Rotating Reference Frame ◽  
Speed Up ◽  
Fan Blade ◽  
Simulated Flow

A comprehensive three-dimensional CFD approach and experimental study is developed for a 6-ft diameter commercial axial fan with rotational speed up to 1014 rpm. The use of sophisticated CFD software has made it possible to simulate fluid flow in complex moving geometries found in rotating machinery such as fans, pumps compressors, etc. In this paper, FLUENT is used to study an axial fan performance. Simulations are performed for steady state conditions using an implicitly rotating reference frame for the blades. Experimental studies are also conducted to visualize the flow on fan blade surface by using tuft method. The pressure and velocity distribution in front of the fan and the uncertainty dynamic pressure field measurement are also carried out. Comparisons between CFD simulation results and experimental measurement are found to be reasonable.

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