PDF Publication Title:
Text from PDF Page: 005
Touchard 5 laminar layer detached detachment in laminar transition reattachment in turbulent turbulent layer attached fowler detachment in turbulent airfoil turbulent layer detached However, if no separation exists on an airfoil in motion the drag is obviously smaller in laminar than in turbulent, but if the separation occurs it is generally interesting to enhance the transition to turbulence in order to delayed the separation, this is one of the techniques used. Anyway, in the case of airfoils like wings or airplane body, delaying the separation will induce a noticeable favorable influence on the efficiency of the airplane. In the next paragraph, we are going to examine the different techniques which have been considered to delay the air flow detachment. III. AERODYNAMIC FLOW CONTROL We have seen that drag and lift play an important role in aeronautics and are very closely related to the flow regime and configuration around the different parts of a plane. The goal of flow control is to perform devices or processes which induce the flow configuration and regime wished at a given flight phase of the airplane (takeoff, cruise or landing). Indeed, during these different phases the goal wished may be totally different, more, trying to stay in one regime may induced a configuration worst that to pass in another regime. For instance, for the same velocity, the drag is smaller for a laminar flow than for a turbulent one, but a laminar boundary layer is very sensitive to the separation process while the turbulent one is more robust, thus, trying to stay in laminar may induce separation which finally gives a higher drag and smaller lift than a turbulent regime. Thus, the action to be taken depends generally on several parameters and is sometimes a compromise. As Gad-el-Hak in a flow control reference book [8], it is usual to distinguish two kinds of control: passive or active. Passive controls do not use external energy to modify the flow, while active controls use external energy. Passive control devices are generally permanently fixed on the aircraft and cannot be removed, even, they may be a part of the air plane specially designed to control a part of the flow around its body. This is for instance the case of curved end of wing (figure 16). In opposite way, active control devices or processes may be acting or not depending on the flow configuration. Even if the classification of retractable devices has been sometimes debatable, they will be, following, classified as active control devices because they can be modify in function of the flight condition (takeoff, cruise or landing). Fig. 15. The different zones around an airplane wing with a fowler. curved end of wing Fig. 16. Example of passive control device. A. Passivecontroldevices. Two main devices have been perfected for control in aeronautics, riblets and Large Eddy Breakup devices (LEBU). Riblets (figure 17) are small grooves aligned with the free air stream. They modify the near-wall structure of the boundary layer. Walsh and al from NASA-Langley laboratory [9] examined the drag reduction for different riblets profiles (figure 18). They found that the best shape seemed to be sharp peak and sharp or round valley. With such riblets profile they found 8% of drag reduction. The size of the riblets (distance between valley and peak) is rather small around 35 μm and can be made on plastic adhesive films stuck on the airfoil. Aircraft manufacturers like Boeing and Airbus have tried such films with 5 to 6% drag reduction. The purpose of LEBUs [10] is to alter, breakup, or sever the large vortices appearing at the outer edge of the turbulent boundary layer existing around an airfoil. They are usually made of small strips or airfoils (like NACA0009 in the case of the example shown inPDF Image | Plasma actuators for aeronautics applications
PDF Search Title:
Plasma actuators for aeronautics applicationsOriginal File Name Searched:
02-01-001.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |