Investigation of aeroacoustics and flow dynamics of a NACA 0015 airfoil with a Gurney flap using TR-PIV

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(1)Delft University of Technology. Investigation of aeroacoustics and flow dynamics of a NACA 0015 airfoil with a Gurney flap using TR-PIV Shah, J.; Sciacchitano, Andrea; Pröbsting, Stefan. Publication date 2016 Document Version Final published version Published in Proceedings of the 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics. Citation (APA) Shah, J., Sciacchitano, A., & Pröbsting, S. (2016). Investigation of aeroacoustics and flow dynamics of a NACA 0015 airfoil with a Gurney flap using TR-PIV. In Proceedings of the 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics Lisbon, Portugal: Springer. Important note To cite this publication, please use the final published version (if applicable). Please check the document version above.. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim.. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10..

(2) PROCEEDINGS OF THE. 18th INTERNATIONAL. SYMPOSIUM ON APPLICATION OF LASER AND IMAGING. TECHNIQUES TO FLUID MECHANICS.

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(13) The instantaneous velocity and vorticity fields show the flapping motion of the wake and the coherent vortex shedding process. The tonal peaks are clearly audible and correspond to the vortex shedding frequency. The PSD of the flow fluctuations and acoustic spectra did not indicate a secondary mode of shedding in case of turbulent boundary layer. The Strouhal numbers of the vortex shedding are found to be close to that of a bluff body in a flow. Causality correlation between pressure fluctuations in the farN field and the near field fluctuations indicates that the vertical velocity in the wake of the model is highly correlated with the farNfield pressure fluctuations. This study provides an example of the potential of the causality correlation technique in identifying flow structures/regions highly correlated with noise in case of complex highNlift devices, making it possible to design flaps with lower acoustic emissions.O. . . . ),O-FO#,, .O()#-O"-O(O-/$.O) O,-,"O/O.)O."O!,)1#(!O(/',O) O#,*),.-O (O#.-O .O)(O-/,,)/(#(!O)''/(#.#-OJ FO8679KEO)3FO."O()#-O!(,.O3O"#!"N&# .O 0#-O "-O )'O )'*,&O .)O .".O ) O ./,) (O (!#(-O J),43(-%#FO 8676KEO O "#!"N&# .O 0#FO *,-(.O )(O &')-.O (3O #,, .FO #-O ."O .,#&#(!N!O &*FO 1"#"O 2#-.-O #(O O 0,#.3O ) O !)'.,#-O (O )'*&2#.#-EO (O )'*,.#0&3O -#'*&O .3*O ) O &*FO 1"#"O #-O&-)O )/(O)(O ,#(!O ,-O J

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(36) 4* .4'2.#4+/.#, 7-0/3+5-/.4*' 00,+%#4+/. /( #3'2 #.&-#)+.) '%*.+15'3 4/ ,5+& '%*#.+%3࣭ 8 ࣭ "– . . -O,(.&3O*)#(.O)/.O3O((#(!OEOJ867:KFO.",O(OO-)'O'#!/#.3O)(O."O&).#)(O) O the ‘actual source’ based on the maximum values of ܴజᇲ ௣ᇲ EO (O "-O .)O O , /&O 1"#&O concluding that higher values of correlation represent the ‘true source of sound’ since there can. be significant correlation in structures downstream of the upstream ‘source of sound’. Therefore ."O"#!"O0&/-O) O),,&.#)(O#(O#!/,O76O)Onot necessary mean they are the ‘sources’, but they (O&-)OO/O.)O(O/*-.,'O-)/,O(O)(0.O)1(-.,'EO"#-O#-O'O&,O1"(O."O ),,&.#)(O /(.#)(O-OO /(.#)(O) O ߬ O-"# .FOܴజᇲ ௣ᇲ ሺ߬ሻFO#-O&/&.EOO. O . Ĳ PV. Ĳ -0.5 ms. Ĳ= -1 ms. Ĳ -1.5ms. . O. Fig 11: Contour plot of ܴజᇲ௣ᇲ ሺ߬ሻ for different ߬ (GF6-AOA8-V30 case). )O&/&.Oܴజᇲ ௣ᇲ O-OO /(.#)(O) O߬ O-"# .FO#.O#-O#'*),.(.O.)O #,-.O.%O#(.)O)/(.O."O*,)*!.#)(O. .#'O) O)/-.#O10-O.)O."O'#,)*")(EO#,-.O ߬଴ FO#EEO."O*)#(.O1",O4,)O&!O.1(O."O.1)O. -#!(&-O#-O*,-(.FO#-O&/&.O/-#(!O,)--N),,&.#)(EO"O.'*),&O-"# .O),,-*)(#(!O.)O."O '2#'/'Ovalue of correlation between the two signals is taken as the ‘starting point’ of the two. -#!(&-EO"#-O#-O)(O.)O.%O#(.)O)/(.O."O*,)*!.#)(O.#'O-O1&&O-O."O&3-O/O.)O,,),-O #(O+/#,#(!O."O'-/,'(.-O#(OO-3(",)(#4O'((,EO"O)(.)/,O*&).O) OOܴజᇲ ௣ᇲ ሺ߬ሻJ#!/,O. 77KO-")1-O.".O-"# .#(!O."O)/-.#O*,--/,O-#!(&O1#."O,-*.O.)O."O ߭ᇱ &/./.#)(-O) O."O &)1O. #(O."O(!.#0O#,.#)(OJ ߬ O,-#(!O ,)'O6O.)O(!.#0O0&/-KO/--O."O),,&.#)(O /(.#)(O. .)O')0O#(O."O)1(-.,'O#,.#)(O-O#(#.O3O&..,OEOO.

(37) 4* .4'2.#4+/.#, 7-0/3+5-/.4*' 00,+%#4+/. /( #3'2 #.&-#)+.) '%*.+15'3 4/ ,5+& '%*#.+%3࣭ 8 ࣭ "–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ig 12: Contour plots of magnitude square coherence ɀ. and the corresponding phase difference plot (right). O "O'!(#./O-+/,N)",(Oߛ ଶ ‫׎‬ᇲ ௣ᇲ #-O #(O3FO ߛ ଶ ‫׎‬௣ᇲ ሺ݂ሻ ൌ ୋ. ȁୋ‫׎‬౦ᇲ ሺ୤ሻȁమ. OOOOOOOOOOOOOO ‫ ׎׎‬ሺ୤ሻୋ ౦ᇲ౦ᇲ ሺ୤ሻ. O. . O. O. O. ଶ. O. . ୴ᇲ୮ ᇲ at shedding frequency (left). O. O. O. O. J8KO.

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