國立虎尾科技大學 |

Flow field and acoustic characterization of non-axisymmetric jets.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	Flow field and acoustic characterization of non-axisymmetric jets./
作者:	Valentich, Griffin M.
面頁冊數:	1 online resource (104 pages)
附註:	Source: Masters Abstracts International, Volume: 55-05.
Contained By:	Masters Abstracts International55-05(E).
標題:	Aerospace engineering. -
電子資源:	click for full text (PQDT)
ISBN:	9781339818887

Flow field and acoustic characterization of non-axisymmetric jets.
Valentich, Griffin M.

Flow field and acoustic characterization of non-axisymmetric jets. - 1 online resource (104 pages)

Source: Masters Abstracts International, Volume: 55-05.

Thesis (M.S.)

Includes bibliographical references

Asymmetric jets are becoming more prevalent and may offer significant advantages over traditional axisymmetric nozzles for propulsion as well as fluidic mixing applications. The purpose of this work is two fold: 1) to investigate the effect nozzle exit geometry has on jet development and far field radiated noise of M = 0:9 jets and 2) to study the effect various levels of screech tone self excitation has on jet evolution and the production of streamwise vorticity. Three converging nozzles of various exit geometry (rectangular, elliptic, and round) were utilized to perform the first study, while a supersonic rectangular nozzle was employed to complete the second. All asymmetric nozzles in this work had an aspect ratio of 4:1. To study the flow field features, two dimensional streamwise particle image velocimetry (PIV) as well as three component PIV at select cross planes was performed. Far field acoustic measurements were acquired for the converging nozzles to determine the differences exhibited in the radiated exhaust noise from the major and minor axes of the asymmetric jets compared to the round jet.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781339818887Subjects--Topical Terms:

686400
Aerospace engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Flow field and acoustic characterization of non-axisymmetric jets.
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100 1 $a Valentich, Griffin M. $3 1180193
245 1 0 $a Flow field and acoustic characterization of non-axisymmetric jets.
264 0 $c 2016
300 $a 1 online resource (104 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Masters Abstracts International, Volume: 55-05.
500 $a Adviser: Rajan Kumar.
502 $a Thesis (M.S.) $c The Florida State University $d 2016.
504 $a Includes bibliographical references
520 $a Asymmetric jets are becoming more prevalent and may offer significant advantages over traditional axisymmetric nozzles for propulsion as well as fluidic mixing applications. The purpose of this work is two fold: 1) to investigate the effect nozzle exit geometry has on jet development and far field radiated noise of M = 0:9 jets and 2) to study the effect various levels of screech tone self excitation has on jet evolution and the production of streamwise vorticity. Three converging nozzles of various exit geometry (rectangular, elliptic, and round) were utilized to perform the first study, while a supersonic rectangular nozzle was employed to complete the second. All asymmetric nozzles in this work had an aspect ratio of 4:1. To study the flow field features, two dimensional streamwise particle image velocimetry (PIV) as well as three component PIV at select cross planes was performed. Far field acoustic measurements were acquired for the converging nozzles to determine the differences exhibited in the radiated exhaust noise from the major and minor axes of the asymmetric jets compared to the round jet.
520 $a In comparing the effect exit geometry has on the development of a M = 0:9 jet, it was determined that the shear layers in the major and minor axes developed at similar rates, however, the jet half width in the minor axis exhibited a larger growth rate than the major axis. It was also determined that neither of the asymmetric sonic jets exhibited the axis-switching phenomenon within the measurement domain. Significant streamwise vorticity is noted on the low speed side of the shear layer for the asymmetric jets in the corner regions and areas of small curvature. Moreover, this streamwise vorticity was observed to significantly effect the jet half width in the major axis of the elliptic jet. Acoustic results reveal that there is a strong dependence on frequency range concerning the amount of energy propagated to the far field for each different jet and axis. At low frequencies, the round jet is louder than both axes of the asymmetric jets at polar angles larger than 110°. As the investigated range of frequencies is increased, the primary direction of propagation of noise shifts towards sideline angles for all jets and axes. At the highest range of frequencies investigated, the minor axis of the asymmetric jets produced more noise compared to the equivalent round jet while considerably less noise is produced at polar angles of about 120° -- 130° in the major axis direction. Overall sound pressure levels (OASPL) show that the OASPL from the rectangular jet in the plane containing the major axis is lower than the equivalent round jet for aft quadrant angles; the main contributor to the overall reduction is from the highest frequency components.
520 $a In order to determine the impact screech tone amplitude has on jet development, flow field characteristics of a moderate aspect ratio supersonic rectangular jet were examined at two overexpanded, a perfectly expanded, and an underexpanded jet conditions. The underexpanded and one overexpanded operating condition were of maximum screech, while the second overexpanded condition was of minimum screech intensity. The results show that streamwise vortices present at the nozzle corners along with vortices excited by screech tones play a major role in the jet evolution. The location of streamwise vortex amplification in cases of screech is strongly tied to the downstream shock cell number and the traditional source of the screech tone. All cases except for the perfectly expanded operating condition exhibited axis switching at streamwise locations ranging from 11 to 16 nozzle heights, h, downstream of the exit. The overexpanded condition of maximum screech showed the most upstream switch over, while the underexpanded case showed the farthest downstream. Both of the maximum screeching cases developed into a diamond cross sectional profile far downstream of the exit, while the ideally expanded case maintained a rectangular shape. The overexpanded minimum screeching case eventually decayed into an oblong profile.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Aerospace engineering. $3 686400
650 4 $a Mechanical engineering. $3 557493
650 4 $a Acoustics. $3 670692
655 7 $a Electronic books. $2 local $3 554714
690 $a 0538
690 $a 0548
690 $a 0986
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a The Florida State University. $b Mechanical Engineering. $3 1180194
773 0 $t Masters Abstracts International $g 55-05(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10120708 $z click for full text (PQDT)