藉由聲波激擾支配後傾噴流在橫風中之流動與混合特性

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研究生：	SUKENDRO SUKENDRO BROTO SASONGKO
論文名稱：	藉由聲波激擾支配後傾噴流在橫風中之流動與混合特性 Modulating flow and mixing characteristics of a backward-inclined jet in crossflow by acoustic-excitation
指導教授：	黃榮芳 Rong-Fung Huang
口試委員:	林顯群 Sheam-Chyun Lin 孫珍理 Chen-Li Sun 閰順昌 Shun-Chang Yen 趙振綱 Ching-Kong Chao 許清閔 Chin-Ming Hsu 黃榮芳 Rong-Fung Huang
學位類別：	博士 Doctor
系所名稱：	工程學院 - 機械工程系 Department of Mechanical Engineering
論文出版年：	2021
畢業學年度：	109
語文別：	英文
論文頁數：	125
中文關鍵詞：	橫流噴射、調製射流、后倾喷气机、剪切層不穩定性、湍流渦流、混合能力
外文關鍵詞：	jet in crossflow, modulating jet, backward-inclined jet, shear-layer instability, turbulence eddies, mixing capability
相關次數：	點閱：213 下載：0
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本論文在開迴路風洞中，使用實驗方法研究受聲波激擾之後傾噴流，在橫風的流場與混合特性。在噴流組件中安裝揚聲器，使得噴嘴出口產生脈衝噴流。藉由雷射輔助煙霧流場可視化方法，觀察噴流在橫風中的瞬時與時間平均流場照片;應用二位元邊緣偵測技術於長時間曝光的流場照片，量測噴流的擴散寬度與穿透高度;利用熱線風速儀偵測流場瞬時速度，計算紊流強度、紊流時間尺度與長度尺度;使用追蹤氣體濃度檢測方法，偵測噴流於橫風中的混合特性。受聲波激擾之後傾噴流在橫風中的流場行為，在擾動強度與擾動史卓數的域面上可畫分出三個流場特徵模態: 同步振盪噴流、過渡及同步剪流層渦漩。在同步振盪噴流模態，高軸向的噴流擾動造成噴流呈現劇烈的橫向擾動，使得噴流橫向擴散，增大噴流橫向擴散寬度及穿透高度。由橫向速度訊號量測結果顯示，紊流強度增大，而紊流時間尺度與長度尺度減小，因此，造成噴流的混合性能提升。在小後傾角時，聲波激擾明顯地提升噴流擴散寬度與混合的特性。隨著後傾角增加至臨界角度20o時，噴流擴散寬度與混合特性達到最大值。控制後傾角低於20o時，能夠引致噴流射入橫風中的混合特性增強。透過聲波激擾搭配後傾角的控制，對於工業中需要快速與有效流體混合的應用，能夠產生較大的助益。

The flow and mixing characteristics of an acoustically excited backward-inclined jet in crossflow were experimentally investigated in an open-loop wind tunnel. A loudspeaker installed in the nozzle assembly was used to generate the pulsating jet. The instantaneous and time-averaged smoke flow patterns were obtained by the laser-light-sheet-assisted flow visualization method. The binary edge detection method was employed to the long-exposure smoke flow images to measure the jet spread width. The turbulence intensities, as well as the Lagrangian integral turbulence time and length scales, were obtained using a hotwire anemometer. The mixing characteristics were examined using the tracer-gas concentration detection technique. The excited backward-inclined jet in crossflow presented three characteristic flow modes in the domain of jet pulsation intensity and excitation Strouhal number: synchronized oscillating jet, transition, and synchronized shear-layer vortices. The synchronized oscillating jet exhibited violent transverse oscillations due to the high axial jet pulsations. The transverse jet width and jet penetration height were enlarged. The turbulence intensities were significantly increased, and the turbulence time and length scales were decreased, therefore led to a significant enhancement in the jet-fluid dispersions and mixing capabilities. A small jet backward inclination angle could lead to an increase of jet-fluid dispersion and transverse jet spreading width. There existed a critical jet backward inclination angle of 20 at which the jet-fluid dispersion index and transverse jet spreading width attained the maximum values. Arranging the jet backward inclination angle at values smaller than 20 could induce an increase in dispersion of the pulsed jet in crossflow and benefit the industrial applications which required fast and efficient jet-fluid dispersion and mixing.

TABLE OF CONTENTS

摘要…………………………………………...……………………………..…………...…...i
ABSTRACT……………………………………………………………………...……………ii
ACKNOWLEDGEMENTS…….………………………………………………..…...………iii
CONTENTS…………………………..….………………………………………..…….…….v
NOMENCLATURE………………………..………………………………..………….......viii
TABLE CAPTIONS…………………………………………….…………………..…......….x
FIGURE CAPTIONS…………………………………………………………....…...….........xi
CHAPTER 1 Introduction……...……………………………………………..……………….1
1 Motivation………………………………………………………………...……….……1
2 Literature survey……………………….………………………………………..……...5
3 Scope of present work…………..………………………….…...………………........…9
CHAPTER 2 Experimental methods…………………………………………….….…..……11
1 Experimental apparatus……………………………………...………...………………11
1.1 Open-loop wind tunnel……………………………………....………...…………11
1.2 Jet flow supply system…………………………………………………...…....….12
1.3 Smoke flow generator…………………………………………………...…….….13
1.4 Acoustic excitation generator…………………………………………..………...16
2 Experimental instrument and methods……………………………………..………….18
2.1 Flow visualization……………………………………..…………………………18
2.2 Jet boundaries detection……………………………………...…………...………19
2.3 Instability frequency detection………………………………………………...…20
2.4 Tracer-gas concentration…………………………………………..…….….……22
CHAPTER 3 Jet velocity pulsations…………..………………………...…………….......….24
1 Time histories of jet-exit velocity………………………………………..…...…….…24
1.1 Time histories of jet-exit velocity at Ip less than 1.2 with R = 1.6………………..24
1.2 Time histories of jet-exit velocity at the values Ip = 1.2 with R = 1.2……………26
2 Jet pulsation property…….……………………….......………………...………...…...27
CHAPTER 4 Characteristics flow behaviors…………………………………………………29
1 Characteristic flow patterns of pulsed jets at  = 30……...….…....…………..…..…29
2 Characteristics flow regimes of pulsed jets at  = 30…….........................………….31
3 Effect of different  on the non-excited jets…………………………………………..33
4 Effect of different Ip on synchronized oscillating jets at  = 0……………..…….….34
5 Effect of different Stexc on flow pattern evolution of synchronized oscillating jets…..35
6 Effect of different θ on flow pattern evolution of synchronized oscillating jets……...37
7 Effect of different θ on flow pattern evolution of synchronized shear-layer.…….…..39
8 Visuals of jet spreading at various Stexc……………………………………………….40
9 Jet column deflection angles α of synchronized oscillating jet near the exit……......….43
10 Jet penetration heights H/d at various Stexc……………………………………….…..45
10.1 Jet penetration heights H/d at R = 1.6 and Ip less than 1.2………………….….45
10.2 Jet penetration heights H/d at R = 1.2 and Ip = 1.2…………………………….46
11 Jet spreads width W/d………………………………………………………………...47
11.1 Jet spreads width W/d at various Stexc and R = 1.6………………………......….47
11.2 Jet spreads width W/d of synchronized oscillating jets with various θ………...49
11.3 Jet spreads width W/d at various Stexc and R = 1.2………………………...…....51
12 Shear-layer instability of synchronized oscillating jets with R = 1.6…………………52
12.1 Mean jet exit velocities………………………………………………………..52
12.2 Transverse turbulence intensities………………………………………...……53
12.3 Time and length scales of turbulence………………………………………….56
13 Shear-layer instability at various Stexc at R = 1.2……………………...………………58
13.1 Transverse turbulence intensities……………………………………...………58
13.2 Time and length scales of turbulence………………………………………….59
CHAPTER 5 Mixing characteristics………………………………………………………….61
1 Dispersion of jet fluids of non-excited jets at different R……………………………..61
2 Dispersion of jet fluids of excited jets…………………………………………….……62
2.1 Dispersion of jet fluids excited at various Stexc with R = 1.2……………………62
2.2 Dispersion of jet fluids excited at various Stexc with R = 1.6……………………63
2.3 Dispersion of jet fluids of synchronized oscillating jet at different θ……………64
3 Mixing indexes of pulsed jets………………….…………………………...………….65
3.1 Mixing indexes at various Stexc with R = 1.2………………………..…….…….65
3.2 Mixing indexes at various Stexc with R = 1.6……………………….……..…….66
3.3 Mixing indexes of synchronized oscillating jet at different θ…………………..67
CHAPTER 6 Conclusion and Recommendations……………………………..….….…….....70
1 Conclusion……………………………………….……………………………………70
2 Recommendations…………………………………......………………………………71
REFERENCES…………………………………………...………………………….....….....73


                                

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全文公開日期 2026/10/20 (校內網路)
全文公開日期 2026/10/20 (校外網路)
全文公開日期 2026/10/20 (國家圖書館：臺灣博碩士論文系統)

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