Synthetic jet
{{Short description|Type of jet flow on fluid dynamics}}
In fluid dynamics, a synthetic jet flow—is a type of jet flow, which is made up of the surrounding fluid.{{cite journal | last1 = Smith | first1 = Barton | last2 = Glezer | first2 = Ari | year = 1998 | title = Smith, B. L., & Glezer, A. (1998). The formation and evolution of synthetic jets | journal = Physics of Fluids | volume = 10 | issue = 9| pages = 2281–2297| doi = 10.1063/1.869828 }} Synthetic jets are produced by periodic ejection and suction of fluid from an opening. This oscillatory motion may be driven by a piston or diaphragm inside a cavity among other ways.{{cite journal | last1 = Agrawal | first1 = Amit | last2 = Verma | first2 = Gunjan | year = 2008 | title = Similarity analysis of planar and axisymmetric turbulent synthetic jets | journal = International Journal of Heat and Mass Transfer | volume = 51 | issue = 25–26| pages = 6194–6198 | doi = 10.1016/j.ijheatmasstransfer.2008.04.011 | bibcode = 2008IJHMT..51.6194A }}{{cite journal | last1 = Kotapati | first1 = Rupesh B. | last2 = Mittal | first2 = Rajat | last3 = Louis | first3 = N. Cattafesta III | year = 2007 | title = Numerical study of a transitional synthetic jet in quiescent external flow | journal = Journal of Fluid Mechanics | volume = 581 | pages = 287–321 | doi = 10.1017/S0022112007005642 | bibcode = 2007JFM...581..287K | s2cid = 7596423 }}
A synthetic jet flow was so named by Ari Glezer since the flow is "synthesized" from the surrounding or ambient fluid. Producing a convectional jet requires an external source of fluid, such as piped-in compressed air or plumbing for water.
Synjet devices
Synthetic jet flow can be developed in a number of ways, such as with an electromagnetic driver, a piezoelectric driver, or even a mechanical driver such as a piston. Each moves a membrane or diaphragm up and down hundreds of times per second, sucking the surrounding fluid into a chamber and then expelling it. Although the mechanism is fairly simple, extremely fast cycling requires high-level engineering to produce a device that will last in industrial applications.
For hot spot thermal management, the Synjet, commercially offered by Austin, Texas–based company Nuventix,{{Cite web |url=http://www.nuventix.com/ |title=Nuventix - Active Thermal Management Hot Spot Cooling, Air Cooled Heat Exchangers: Nuventix |access-date=2009-01-13 |archive-date=2009-01-05 |archive-url=https://web.archive.org/web/20090105224119/http://www.nuventix.com// |url-status=live }} was patented in 2000 by engineers at Georgia Tech.{{cite web |url=http://www.venturelab.gatech.edu/Portals/57/december12003.htm |title=VentureLab company commercializes synthetic jets for cooling |access-date=2007-09-18 |url-status=dead |archive-url=https://web.archive.org/web/20060902074052/http://www.venturelab.gatech.edu/Portals/57/december12003.htm |archive-date=2006-09-02 }} The tiny synjet module creates jets that can be directed to precise locations for industrial spot cooling. Traditionally, metallic heat sinks conduct heat away from electronic components and into the air, and then a small fan blows the hot air out. Synjet modules replace or augment cooling fans for such devices as microprocessors, memory chips, graphics chips, batteries, and radio frequency components. Additionally, SynJet technology has been used for the thermal management of high power LEDs{{Cite web | url=http://www.nuventix.com/led-cooling/. | title=Aavid, Thermal Division of Boyd Corporation | access-date=2013-02-07 | archive-date=2015-04-07 | archive-url=https://web.archive.org/web/20150407021514/http://www.nuventix.com/led-cooling/ | url-status=live }}
Synthetic jet modules have also been widely researched for controlling airflow in aircraft to enhance lift, increase maneuverability, control stalls, and reduce noise.{{cite journal | last1=KOTAPATI | first1=RUPESH B. | last2=MITTAL | first2=RAJAT | last3=MARXEN | first3=OLAF | last4=HAM | first4=FRANK | last5=YOU | first5=DONGHYUN | last6=CATTAFESTA | first6=LOUIS N. | title=Nonlinear dynamics and synthetic-jet-based control of a canonical separated flow | journal=Journal of Fluid Mechanics | publisher=Cambridge University Press (CUP) | volume=654 | date=2010-05-11 | issn=0022-1120 | doi=10.1017/s002211201000042x | pages=65–97| bibcode=2010JFM...654...65K | s2cid=9803739 }} Problems in applying the technology include weight, size, response time, force, and complexity of controlling the flows.{{Cite web|url=http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=2619&DID=116064&action=detail|title=MRS Website : Piezoelectric Actuators for Synthetic Jet Applications}}{{Dead link|date=October 2023 |bot=InternetArchiveBot |fix-attempted=yes }}http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000129000007000825000001&idtype=cvips&gifs=yes {{Dead link|date=February 2022}}{{Cite web|url=https://sbir.nasa.gov/SBIR/abstracts/05/sttr/phase2/STTR-05-2-T2.02-9831.html|title=Active Flow Control with Adaptive Design Techniques for Improved Aircraft Safety|website=sbir.nasa.gov|access-date=2021-10-27|archive-date=2021-06-09|archive-url=https://web.archive.org/web/20210609121814/https://sbir.nasa.gov/SBIR/abstracts/05/sttr/phase2/STTR-05-2-T2.02-9831.html|url-status=live}}{{cite web |url=http://www.patentstorm.us/patents/7159383-claims.html |title=Apparatus, method and system for gas turbine engine noise reduction - US Patent 7159383 Claims |access-date=2014-01-07 |url-status=dead |archive-url=https://archive.today/20140107235226/http://www.patentstorm.us/patents/7159383-claims.html |archive-date=2014-01-07 }}
A Caltech researcher has even tested synthetic jet modules to provide thrust for small underwater vehicles, modeled on the natural jets that squid and jellyfish produce.{{Cite book|chapter-url = https://ieeexplore.ieee.org/document/1570116|doi = 10.1109/ROBOT.2005.1570116|chapter = Synthetic Jet Propulsion for Small Underwater Vehicles|title = Proceedings of the 2005 IEEE International Conference on Robotics and Automation|pages = 181–187|year = 2005|last1 = Thomas|first1 = A.P.|last2 = Milano|first2 = M.|last3 = g'Sell|first3 = M.G.|last4 = Fischer|first4 = K.|last5 = Burdick|first5 = J.|isbn = 0-7803-8914-X|s2cid = 15262116|url = https://authors.library.caltech.edu/25088/1/Thomas2005p96102008_Ieee_International_Conference_On_Robotics_And_Automation_Vols_1-9.pdf|access-date = 2019-07-15|archive-date = 2017-12-02|archive-url = https://web.archive.org/web/20171202120100/https://authors.library.caltech.edu/25088/1/Thomas2005p96102008_Ieee_International_Conference_On_Robotics_And_Automation_Vols_1-9.pdf|url-status = live}} Recently, research team at the School of Engineering, Taylor's University (Malaysia), successfully used synthetic jets as mixing devices.{{cite journal | last=Al-Atabi | first=Mushtak | title=Experimental Investigation of the Use of Synthetic Jets for Mixing in Vessels | journal=Journal of Fluids Engineering | publisher=ASME International | volume=133 | issue=9 | date=2011-09-01 | issn=0098-2202 | doi=10.1115/1.4004941 | page= | url=http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=1439115 | access-date=2014-02-07 | archive-date=2014-02-23 | archive-url=https://web.archive.org/web/20140223004547/http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=1439115 | url-status=live | url-access=subscription }} Synthetic jets prove to be effective mixing devices especially for shear sensitive materials.