Micro-technology saves jet fuel

Occasionally jetting down to southerly climes for a long weekend is no longer a rarity. To put it succinctly, air travel is booming. Aircraft should therefore get to their destinations with as much fuel-economy as possible. One thing that can help is the use of special fludic systems that are called AFC actuators. They sit along the trailing edges of the aircraft’s wings within the flaps and are deployed during take-offs and landings, blowing air through tiny holes in the surface of the flap. The actuators delay the onset of boundary layer separation and increase the aircraft’s lift. Researchers at the Fraunhofer Institute for Electronic Nano Systems ENAS in Chemnitz, Germany, have now been able to increase the performance level of these actuators as part of the “Clean Sky” major industrial project involving over eighty partners from research and industry. They have optimized synthetic jet actuators (SJA) to such an extent that the air flows out the holes one-and-a-half times faster. In addition, the SJAs are smaller than usual. Instead of the four to five centimeters (about one-and-a-half to two inches) previously, they are now only about one centimeter wide (.4 inches). As a result, many more of the actuators can fit within the aircraft’s flaps.

The researchers have also optimized the pulsed jet actuators. In this case, pressurized air flows from a valve in the base, filling a chamber, and then escapes through the hole onto the upper wing surface. With the help of micro-machining techniques, the scientists were able to design the valve to be so small that it can be placed directly beside the hole. This has also led to improvements in performance. While a synthetic jet actuator prototype has already been tested, the pulsed jet actuator is still in development.

Fraunhofer Institute for Electronic Nano Systems ENAS  
Technologiecampus 3 | 09126 Chemnitz | www.enas.fraunhofer.de
Contact: Martin Schüller | Phone +49 371 45001 242 | martin.schueller@enas.fraunhofer.de
Press: Dr. Martina Vogel | Phone +49 371 45001-203 | martina.vogel@enas.fraunhofer.de

Sensors protect the Rotterdam quayside

The saline seawater ceaselessly eats into the concrete of the quayside, day after day, year after year. These are the most difficult conditions that steel-reinforced concrete has to withstand. The salt, in form of salt ions, penetrates the alkaline concrete and neutralizes it, i.e. alters it chemically. The situation becomes especially dire if the ions reach the steel reinforcement. The steel rods corrode, crevices form, and slabs of concrete can fracture and separate. In a word, the quayside loses its stability. However, it is difficult to establish when the harmful ions have penetrated far enough through the concrete to attack the steel as well.

Things are different with the new quayside in Rotterdam. The construction company has integrated passive RFID sensors along the reinforcing rods during quay construction. Once the salt ions reach a sensor, they eat away its special wire. The more of them that are corroded by the ions, the more advanced the corrosion has become. A transponder in the sensor transmits the data to an RFID reader. The extent of the hazard is displayed to the harbor official responsible for the quayside. As a result, maintenance work on the structure can be initiated before the reinforcement is damaged. This makes it possible to save millions in concrete construction costs. The sensor was developed by staff at BS2 Sicherheitssystems GmbH in Boppard, Germany. Researchers of the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg integrated the passive, wireless transponder system. The scientists will be presenting the system at the EURO ID 2013 trade fair in Frankfurt, Germany, from November 5-7 (Hall 4, Booth D08).

Fraunhofer Institute for Microelectronic Circuits and Systems IMS
Finkenstr. 61 | 47057 Duisburg | www.ims.fraunhofer.de
Contact: Frederic Meyer | Phone +49 203 3783-193 | frederic.meyer@ims.fraunhofer.de
Press: Martin van Ackeren | Phone +49 203 3783-130 | martin.van.ackeren@ims.fraunhofer.de

95 percent less lubricant

The less lubricant used in manufacturing, the better it is for the environment, for production costs, and not least for occupational safety as well. The trend is therefore towards micro-lubrication. The limiting factor has long been primarily the reliability of the metering system. At delivery rates below 25 micrograms per second (µg/s), even the smallest irregularities can lead to the machine’s bearings running dry.

Researchers of the Fraunhofer Research Institution for Modular Solid State Technologies EMFT jointly with the GMN Paul Müller Industrie Co. have now developed a micro-lubrication system that can reduce oil consumption by up to 95 percent. However, in order to guarantee a continuous film of lubricant on the bearing surfaces, a new kind of metering monitor was employed by the scientists in Munich. At the completion of each lubricating interval, a gas bubble is injected into the metering channel. Several sensors in this channel are able to measure its precise size and speed, and determine from this the precise amount of oil delivered. The measurements are processed by a microchip that can re-adjust the lubrication pump’s frequency for the desired delivery quantity. The reduced amount of oil provides further advantages: it reduces wear and increases the efficiency of the equipment. Presently, the project team is improving the metering algorithm in order to achieve even lower metering rates of as little as 5 µg/s.

Fraunhofer Research Institution for Modular Solid State Technologies EMFT  
Hansastraße 27 d | 80686 München | www.emft.fraunhofer.de
Contact: Dipl.-Ing. Sebastian Kibler | Phone +49 89 54759-227 | sebastian.kibler@emft.fraunhofer.de
Press: Pirjo Larima-Bellinghoven | Phone +49 89 54759-542 | Pirjo.Larima-Bellinghoven@emft.fraunhofer.de