Jump to content

All Activity

This stream auto-updates

  1. Today
  2. Last week
  3. Aeroacoustic performance of fans is essential due to their widespread application. Therefore, the original aim of this paper is to evaluate the generated noise owing to different geometric parameters. In current study, effect of five geometric parameters was investigated on well performance of a Bladeless fan. Airflow through this fan was analyzed simulating a Bladeless fan within a 2 m×2 m×4 m room. Analysis of the flow field inside the fan and evaluating its performance were obtained by solving conservations of mass and momentum equations for aerodynamic investigations and FW-H noise equations for aeroacoustic analysis. In order to design table bladeless fan Eppler 473 airfoil profile was used as the cross section of this fan. Five distinct parameters, namely height of cross section of the fan, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter and aspect ratio for circular and quadratic cross sections were considered. Validating acoustic code results, we compared numerical solution of FW-H noise equations for NACA0012 with experimental results. FW-H model was selected to predict the noise generated by the Bladeless fan as the numerical results indicated a good agreement with experimental ones for NACA0012. To validate 3-D numerical results, the experimental results of a round jet showed good agreement with those simulation data. In order to indicate the effect of each mentioned parameter on the fan performance, SPL and OASPL diagrams were illustrated. Nowadays, the axial and radial fans are employed for various applications, such as cooling systems, air conditioning, ventilation of underground spaces, etc. The aeroacoustic performance of fans have been improved by increasing advancements in the computational fluid dynamics (CFD) and economic growth, then different types of fans with various applications and higher efficiency is offered. In 2009, a new fan was invented that its appearance and performance was different from conventional fans. The main differences of this fan with respect to conventional fans (axial and radial fans) are the multiplying intake air flow and lack of observable impeller [1]. This fan namely Bladeless/Air Multiplier fan was named on the basis of the two mentioned features. Until now, this fan is manufactured for domestic applications by diameter of 30 cm. There are two typical fans widely used: axial and radial types, however Bladeless fans are completely distinct from those fans in mechanism aspect. Bladeless fan is similar to centrifugal fans in terms of radial impellers for intake air and also it is similar to axial fans in terms of preparing higher rate of outlet airflow. Although studies about wall and table bladeless fan are rare in the literature, numerous experimental and numerical studies have been performed on the axial and centrifugal fans. Lin, et al [2], designed a Forward–Curved (FC) centrifugal fan by numerical simulation and experimental tests. They selected NACA 0012 airfoil profile for its blade and indicated that this fan produces a higher maximum flow rate and static efficiency when the blade inlet angle is 16.5º. The influence of enlarged impeller on performance of a centrifugal fan was experimentally examined by Chunxi, et al [3]. By comparison of obtained results, they observed that flow rate, total pressure rise, shaft power and sound pressure level increased while the efficiency of fan decreased for larger blades. Govardhan, et al [4], investigated the flow field in a cross flow fan by three-dimensional simulation via the commercial software code, CFX. They simulated three impeller geometries for different radius ratio and blade angles, and then they compared their efficiency with each other. Sarraf, et al [5], experimentally studied axial fans performance for two identical fans but with different impeller thickness. They indicated that the overall performance of these two fans is same, but the fan with thicker blades contained higher rate of pressure loss by the means of 8%. Also the efficiency of the fan with thinner blades was 3% higher than the fan with thicker blade. Mohaideen [6] improved an axial fan blade by using the finite element method (FEM) and reduced 18.5% of the blade weight after optimizing on the blade thickness via stress analysis by ANSYS commercial software. There are a lot of studies on the generated noise by various airfoils that is carried out by experimental and/or numerical approaches. Chong, et al [7], measured the generated noise by a 2-D NACA 0012 airfoil at the angles of attack 0º, 1.4º and 4.2º, in a wind tunnel. They performed their experiments for some Reynolds numbers between 1×105 and 6×105. The experimental results indicated that the pressure gradient was raised on the airfoil pressure surface by increasing of attack angle, so the noise can be produced by this phenomenon. Devenport, et al [8], carried out experimental tests on the noise propagation of NACA 0012, NACA 0015 and S831 airfoil. The obtained results indicated that the airfoils with more thickness made lower noise and revealed the different angles of attack had little influence on the sound production for NACA 0012 and NACA 0015 airfoil. Casper, et al [9], solved the equations of FW-H and developed new equations. They computed the produced noise by a NACA 0012 airfoil in a low Mach number flow. The analytical results and experimental data for NACA 0012 airfoil were in good agreement. So far, many experimental and numerical studies have been performed on the generated sound by axial and centrifugal fans. Many researchers have used the FW-H equations to predict the sound radiation of fan by numerical simulation. Ballesteros-Tajadura, et al [10], measured the noise of a centrifugal fan via FW-H noise model using the CFD code, FLUENT. By comparing numerical and experimental noise results, they showed the FW-H model was able to predict the tonal noise with reasonable accuracy. Solving FW-H equations, Moon, et al [11] and Cho, et al [12] calculated the amount of radiated sound from an axial fan and a cross flow fan, respectively. Younsi, et al [13], used numerical simulation to predict the noise level in a HVAC forward centrifugal fan. By comparing numerical and experimental data, they showed the good agreement between simulation and the experimental data. In some papers, researchers have studied the source of generating noise in different fans by using the computational aeroacoustics (CAA) [14]. Khelladi, et al [15], calculated the noise of a high rotational speed centrifugal fan via FW-H analogy and solving the Reynolds Averaged Navier-Stokes (RANS) equations. They compared the numerical and experimental data and also evaluated the aerodynamic performance of fan. In 2009, Sorguven, et al [16], studied aerodynamic and aeroacoustic performance of two radial fans. Moreover in their study, LES turbulence modeling and FW-H noise modeling were employed. They showed a satisfied agreement of experimental and numerical results and reported FW-H model as a reasonable model for evaluating aeroacoustic performance of fans. Although Bladeless fan is invented in 2009, but until now aeroacoustic performance of this fan has not been studied numerically or experimentally for different conditions. This fan is designed for home applications by diameter of 30 cm and the only available geometric information is mentioned in patent documentation [1]. In the present study, the effect of five geometric parameters is investigated on performance of a Bladeless fan by diameter 30 cm. The studied parameters are height of fan cross section, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter and aspect ratio for circular and quadratic cross sections. The unsteady conservation of mass and momentum equations are solved to simulate three-dimensional incompressible flow in the Bladeless fan. The Ffowcs Williams and Hawkings (FW-H) formulation is solved to calculate the noise propagation of smart bladeless fan. Firstly, the generated noise of a NACA 0012 airfoil is computed to validate aeroacoustic results by experimental data [17]. The obtained numerical results and the experimental data are in the reasonable agreement, so the FW-H model is employed to measure the tonal noise of Bladeless fan. To validate 3-D numerical simulations, the experimental results of a round jet [18] are compared with numerical simulation results. Since there is not any experimental data about Bladeless fans, round jet is selected due to much similarity. The turbulence in the Bladeless fan is simulated by standard k−ε turbulence model. In order to design cross section of Bladeless fan, Eppler 473 airfoil is chosen among standard airfoils. Eppler 473 airfoil is selected because it is an appropriate airfoil for low Reynolds numbers and high similarity of this airfoil profile to original cross section (designed by inventor) [1]. The volume flow rate is calculated at a distance up to 3 times of nozzle diameter in front of the fan (around 1000 mm) [1]. The numerical results for Bladeless fan show that the investigated parameters in this study are very important to improve the fan performance. Thus these parameters should be considered to design a high performance Bladeless fan. Mechanism of Bladeless Fan This fan is produced for domestic applications and its diameter is 30 cm. The mechanism of inlet and outlet airflow from this fan is shown in Fig. 1. At the first stage, the airflow is sucked into the fan through a rotating DC brushless motor and a mixed flow impeller. The intake air is accelerated by passing through an annular aperture which the cross section of this fan is similar to an airfoil profile. Then air is pushed out from a ring shape region, so the air velocity is increased in this region. A considerable pressure difference is generated between both sides of the fan and the discharged air can be described by Bernoulli’s principle. This pressure difference draws the behind and surrounding air toward front of fan. Therefore, a smart tower bladeless fan amplifies the intake air by drawing the air behind and around the fan. Thereby the inventor of this fan claims that [1] this fan multiplies intake air at about 15 times at distance 3D front of fan (around 1000-1200 mm) [1, 19]. All of described stages are shown in Fig.
  4. Earlier
  5. Hi! I am very interested in even paying someone to help me with Exactly what you stated, " I'm offering to help clone or isolate wild samples for use in your own learning or to cultivate, even to create a liquid culture. I can also help make spore syringes" Many mushrooms are currently growing on my property. I would like to use them to make more and eventually have a fungi farm of my own. My intention is to get the license to sell, next year when the classes are available again. Aside from selling locally, I am more interested in making teas and tinctures for health benefits only. I am not interested in growing any psilocybin shrooms, so no worries there. Please call me if you are willing and able to even spend a day to help me. I would greatly appreciate it. 7658085036 Miranda
  6. Looks like a shaggy parasol, but there are toxic lookalikes. I ate the wrong one early in my learning. I was violently ill for two days.
  7. I found these two mushrooms in the woods behind our house. Does anyone know what they are?
  8. ruthsworld

    Invasive Fungus

    @Liquid Cultured I haven't seen it yet in Indiana, but I haven't been to as many spots to look for it compared to KY. Just be on the lookout. And, yes, it was in the woods on dead logs the times I have seen it. Just wanted to raise awareness since it is new from what they say. I first learned about it from Adam Haritan of Learn Your Land on YouTube and then started looking out for it. Found out that I had IDed it before on iNaturalist, but hadn't known its origin and special interest.
  9. nvm, its not it on my logs, cant remove post so typing this
  10. So cool, thanks for sharing. Just started reading about it and one person uses it to help treat colds. I've been to a few places south and east of Indianapolis and haven't encountered any yet but I don't have that great of a sample size of outings. Did you find it deeper into the woods?
  11. To give a better idea of what I'm talking about with the trash bag technique as I just got around to picking my flush of oysters. The reason you can generally use new egg flats without sterilizing or pasteurization with chemicals because the medium is pretty inert and doesn't aid much in bacterial growth. But since the material is paper pulp and paper is made from trees the mushrooms can create enzymes to break down and use it for nutrients. I also imagine it uses whatever energy was stored in the fruit itself that was used to inoculate these blocks. Had been making dripper bottles of the main chemicals used in testing mushrooms so the label cuttings etc make it look dirty in there. I figured I might as well grab spores while I'm at it since I've gotten a microscope and slides. I like using sterile petri over foil or card stock and once the caps are removed I will cook them or dehydrate. To the reason why I do this is because they will get wrapped with parafilm and put onto a shelf in the hood room. But also, its so when I want to make a spore swab (don't need to fill with water but I suppose you could) or syringes I can fill the petri up with water, swirl it around and then suck a ml or two up in several syringes. I've also found that when you are finished up with doing a bunch of petri work I will empty the agar discs left in the petris, clean them with isopropyl, and then reused for spore prints. Of course you can do this in a ziplock bag, filling with water and all that which is how most store their spore prints but I have an excess of petri. I've also spore printed a few judas ears and will be trying to grow it out on agar this weekend. Anyone can request spores from things I collect and grow for free if we meet or cover shipping. Same goes with the chemical tester solutions.
  12. Asian Beauty Fungus - Screenshot to reduce size. Found in Jefferson Memorial Forest in Jefferson Co., South Louisville, KY. August 2022
  13. Screenshot to reduce size. Found in Jefferson Memorial Forest in Jefferson Co., South Louisville, KY. August 2022
  14. Screenshot to reduce size. Found in Jefferson Memorial Forest in Jefferson Co., South Louisville, KY. August 2022
  15. Screenshot to reduce size. Found in Jefferson Memorial Forest in Jefferson Co., South Louisville, KY. August 2022
  16. ruthsworld

    Invasive Fungus

    Marked as an invasive species. I am starting to notice this more and am wondering if anyone is researching this on how fast it is spreading and reacting in Indiana? First "discovered" in 2009. Radulodon copelandii or Radulomyces copelandii, the Asian beauty, is a fungus typically found on logs and decaying wood. It is native to Asia, where it is known from the Russian Far East, China, Japan, Korea, the Philippines, Malaysia, and Sri Lanka.[1] It now also occurs in North America, where it was first found by J. Ginns and Lawrence Millman in Massachusetts in 2009.[1][2] It is a toothed crust fungus identified by whitish or pale yellowish flattened teeth[3] aging to brownish colors.[2] The basidia are at the tip of each tooth[4] Source: https://en.wikipedia.org/wiki/Radulodon_copelandii
  17. Created a proton email for anyone who wishes to communicate with me outside the forum without giving out personal numbers etc or those who dont use telegram/messaging apps. LiquidCultured at protonmail dot com. Replace "at" with @ and "dot" with . Helps reduce crawler bots reading the email address and sending me spam.
  18. Supposed to be king oysters but thinking that was not the case, must have mixed up liquid cultures. Had a contamination/moisture issues with the rest of the buckets as I got lazy so only 4 of 10 2gallon buckets fruited. Going to try cloning chanterelles with 12" egg crates as the medium like I'm doing with these oysters. Some of you may know the trash bag method and that's basically what I'm doing. Straw logs work great, straw buckets... not so much. TLDR trash bag tek you'd take either grain spawn or the raw fresh fruit and place in the center of a stack of egg crates or news paper/books after saturating the egg cardboard with RO/distilled sterile water while in the trash bag. Tie off bag, wait 3 or 4 weeks then take the now solid block of mycelium out and put into a fruiting chamber or just open the bag enough for decent air exchange. Done
  19. Looks like you've got quite a variety! Thanks for sharing.
  20. -------------- -------------- ------------ ----------- --------------- ----------- -----------
  21. Before someone get's curious, I won't help with any Psilocybe stuff, or anything containing the illicit substances psilocybin and psilocin. While I don't agree with it's status here it's still illegal in Indiana to cultivate or possess, even wild specimens (unless your a mycologist doing research, and even then I'm sure hoops need jumped through). Check out the shroomery website forums for suggestions/sources if you want to continue at your own risk. That site is also a wealth of knowledge from many well know mycologists so even for gourmet mushrooms it's a great place to learn. There is even a company in Indiana that sells the spores/prints, can't recall the name but thought that was interesting.
  22. Call me crazy but I love the lab side of things even though ive never been in a lab and love the petri work. I'm offering to help clone or isolate wild samples for use in your own learning or to cultivate, even to create a liquid culture. I can also help make spore syringes etc. Cloning is quite easy and I can even use a dehydrated specimen so it doesn't have to be fresh. But fresh is quicker to work with. To reiterate; I'm not a mycologist, I just happen to have a lot of experience experimenting.
  23. These came after the forage but will have them ready to use if my dropper bottles get here before this weekend for the Shade park foray. If anyone wants 5ml droppers of these once I can make up a batch of each let me know and ill bring them free to the next meetup.
  24. All images from my phone. I do have a lot of these on the DSLR in macro in the field but those need processed as I shoot in RAW format, then get the photos from over 30mb each to under 2mb so I can post here. I've also put them up on my telegram chat I link to in another post. When I have them all tidy and clean photos I'll upload to my flickr account so you guys can see full resolution and very close details. I'm dehydrating all the things I forage. Don't plan to eat any until I can get into mycologist led forays from the HMS and know a lot more. Not sure if true chanterelle but not quite smooth and not a jack o lantern. Smell like apricots, well, at least smells like the nasal snuff I have that's apricot. I promise I'm not a hipster haha looked edible, type of button? but haven't started trying to ID. Probably should spend more time reading my books as I feel bad getting home and feeling overwhelmed taking multiple species and not getting to them all or skipping some for whatever reason. Gathered these but from google lens AI guess its not a safe mushroom (Orange mycena or start of jack o lanterns?) I'm not dehydrating This red shelf poly smells amazing, rather soft but firm Found on dead log, no bark Varnish mush? Thought I'd lift the tree stump out of the ground before this came off. This one also smelt good, found near the white polypore 2 picture's up Jelly/wood/judas ear. Found some pristine samples, maybe 10-15 total. Nearly impossible to remove from the downed tree trunk but also smells quite nice
  1. Load more activity
×
×
  • Create New...