ች↰ੳᄹ㧔⼾ᯅᛛ⑼ᄢ㒮㧕ޔ⫣↰⑲ᴦ㧔⼾ᯅᛛ⑼ᄢ㧕

ᄢⷙᮨߖࠎᢿੂᵹਛߦ⟎߆ࠇߚㅪ⛯ὐḮ߆ࠄߩᾲ᜛ᢔߩ․ᕈ

ች↰ੳᄹ㧔⼾ᯅᛛ⑼ᄢ㒮㧕ޔ⫣↰⑲ᴦ㧔⼾ᯅᛛ⑼ᄢ㧕

Characteristics of Thermal Diffusion in a Thermal Plume from a Point Source in Large-Scale Shear Turbulence Fields

N. Miyata ^* and 㧴 . Makita ^*

* Dept. of Mech. Eng., Toyohashi University of Technology

ABSTRACT

Thermal diffusion from a point source was experimentally investigated in actively agitated homogeneous and uniform-shear flows with velocity gradients of У U/ У y=0, 2.6, 6.3 s

and turbulent Reynolds numbers of R

㧩 36 㨪 490. Simultaneous measurement was conducted on temperature and velocity fluctuations. Short-time diffusion was realized in the excited turbulence fields of R

=310 㨪 410. Then, the centroid of the plume meandered around the center-line irrespective of the velocity gradient. The lateral integral scale, L

, strongly affected the streamwise growth of the time-averaged plume width. The streamwise decay rate of intermittency factor at the point of the peak temperature, I

, increased with R

.

Key Words: Thermal Diffusion, Plume, Meandering Motion, Shear Flow, Concentration Fluctuation, Flow Control

1. ✜⺰

ᧄ⎇ⓥቶߢߪޔ㜞 R

ታ⃻น⢻ߥᄢ᳇ੂᵹ㘑ᵢ

ࠍ㐿⊒

ߒޔߘࠇࠍ↪޿ߚ৻᭽ᵹਛߩ☸ሶ᜛ᢔታ㛎

߅ࠃ߮ᾲ᜛

ᢔታ㛎

ߦ߅޿ߡࡊ࡞࡯ࡓߩⰬⴕ⃻⽎ࠍ㘑ᵢਛߦౣ⃻ߔ ࠆߎߣߦೋ߼ߡᚑഞߒߚޕታ㓙ߩᄢ᳇ߩᵹࠇߪޔ࿾⴫ㄭ ߊߢ㋦⋥ᣇะߦㅦᐲ൨㈩ࠍᜬߟ㕖ቯᏱߥⶄ㔀ੂᵹ႐ࠍᒻ ᚑߒߡ޿ࠆޕᧄታ㛎ߪᾲ᜛ᢔߦኻߔࠆㅦᐲߖࠎᢿߩᓇ㗀 ࠍ⸃᣿ߔࠆߚ߼ޔᄢⷙᮨ৻᭽ߖࠎᢿੂᵹਛߢᾲ᜛ᢔታ㛎 ࠍ⹜ߺޔᄢⷙᮨੂᵹ᷵ߣࡊ࡞࡯ࡓߩⰬⴕㆇേߣߩ⋧㑐㑐 ଥࠍቯ㊂⊛ߦ᳿ቯߔࠆߎߣࠍ⋡⊛ߣߒߡ޿ࠆޕ

2. ታ㛎ⵝ⟎߅ࠃ߮᧦ઙ

ᄢ᳇ੂᵹ㘑ᵢ᷹ቯ⢵਄ᵹߦޔㅦᐲᚑጀᒻᚑㇱߣੂᵹ⊒

↢ㇱ߆ࠄ᭴ᚑߐࠇࠆߖࠎᢿੂᵹ⊒↢ⵝ⟎

ࠍ⸳⟎ߒߚ ( ࿑ 1) ޕㅦᐲᚑጀᒻᚑㇱߪޔ㋦⋥ᣇะߦಽഀߐࠇߚᵹ〝ߦ㐿 ሹ₸ߩ⇣ߥࠆᄙሹ᧼ࠍᝌ౉ߒޔㅦᐲߖࠎᢿࠍᒻᚑߒߚޕ

ੂᵹ⊒↢ㇱߩᩰሶ⁁ߦ⚵߹ࠇߚ࿁ォゲ ( ᩰሶ㑆㓒㧦

M=35mm) ߦขઃߌߚᡬᜈ⠢ߩേ૞ࡕ࡯࠼ ( ᐔဋㄫⷺ㧦

ǩqޔᦨᄢᡬᜈⷺ㧦rǪq ) ࠍ೙ᓮߒߡޔฦ⒳ߩੂᵹ႐ࠍᒻ ᚑߢ߈ࠆޕߐࠄߦޔ᷹ቯ⢵ᄤ੗ო㕙ߦႺ⇇ጀ೙ᓮⵝ⟎

ࠍ⸳⟎ߒޔო㕙ㄭறߩ᳇ᵹߩടㅦޔๆㄟߺ೙ᓮࠍⴕ߁ߎ ߣߦࠃࠅޔᄤ੗㕙ߦ⊒㆐ߔࠆႺ⇇ጀߩᓇ㗀ࠍૐᷫߒߚޕ

ᩰሶੂᵹ႐ ( Ǫ = r 0 q ) ߣޔബ⿠ੂᵹ႐ ( Ǫ = r 20 㨪 180 q ) ߢޔߘࠇߙࠇᐔဋㅦᐲ൨㈩У U/ У y=0.0, 2.6, 6.3 s

ߩ৻

᭽ᵹ߅ࠃ߮৻᭽ߖࠎᢿੂᵹ႐ ( ੂᵹ࡟ࠗࡁ࡞࠭ᢙ R

=36 㨪 490 ; Case1 㨪 6) ࠍᒻᚑߔࠆߚ߼ޔߖࠎᢿੂᵹ⊒↢ⵝ⟎

ߩᄙሹ᧼ߩ㐿ሹ₸߅ࠃ߮ᡬᜈ⠢ߩǩޔǪࠍ⺞ᢛߒߚ ( ⴫ 1) ޕ

޿ߕࠇ߽ᢿ㕙ਛᔃߩᐔဋᵹㅦ U

㧩 5.0m/s ߢޔᢿ㕙ౝߦ߅

޿ߡ⦟ᅢߥ৻᭽ᕈࠍ଻ߞߡ޿ࠆޕ

ਥᵹߣᐔⴕߦ⸳⟎ߒߚࡄࠗࡊߦㅍࠄࠇߚ᳇ᵹࠍవ┵ߩ ࡅ࡯࠲࡯ ( ౝᓘ㧦 d=5.4mm ޔଏ⛎㔚ജ㧦 6 㨪 7W) ߢടᾲߒ ߡ᡼಴ߒߚޕࡄࠗࡊవ┵ߪੂᵹ႐߇චಽߦ⊒㆐ߒߚੂᵹ

ᩰሶ 90M ਅᵹߦ૏⟎ߒޔ ߘߎࠍᐳᮡゲߩේὐߣߒޔ ᵹࠇޔ

㋦⋥ᣇะࠍ x, y ゲߣߒߚޕ

I-X ဳ಄ᾲੑ✢ᑼ᷷ᐲᵹㅦ⸘

(S/N Ყ㧦 60dB) ࠍ↪޿ߡޔ ടᾲ᳇ᵹ᡼಴ᤨߩ᷷ᐲᄌേ࡮ㅦᐲᄌേ 2 ᚑಽߩหᤨಽ㔌

⸘᷹ࠍⴕߞߚޕ

RegulatorFlow Controller Compressor

Contraction Nozzle

䋨unit䋺mm䋩 90M

300d0

Main Flow

Plume

Injection Pipe(d0=3)

700

U㺙

M=35

Boundary Layer Controler Active Turbulence Generator

y

x

࿑ 1 ታ㛎ⵝ⟎᭎⇛

⴫ 1 ታ㛎᧦ઙ߅ࠃ߮ੂᵹ․ᕈ㊂㧔 x/d=0 㧕 Case Ǫ

[ q ]

[1/s]

u’/U [%] v’/U

[%] L

[mm] L

[mm] R

[-]

Case1 0.0 0.98 0.92 23 11 36 Case2 2.8 1.45 1.26 26 11 50 Case3 0

6.1 3.47 2.87 28 13 90 Case4 0.0 8.9 5.7 584 47 310 Case5 2.8 11.7 7.0 957 62 430 Case6

r 20

180 6.1 15.5 9.8 950 78 㨪 490

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3. ታ㛎⚿ᨐ

࿑ 2 ߦ᷷ᐲ႐ߩ⏕₸ኒᐲ㑐ᢙࠍ␜ߔޕ❑ゲߪᐔဋ᷷ᐲ ߆ࠄቶ᷷ࠍᏅᒁ޿ߚᐔ⋧ኻᐲᢙ߆ࠄ▚಴ߒߚ߽ߩߢޔ৻

᭽ᵹߩ Case1, 4 ߢߪ߶߷ᱜⷙಽᏓߦᓥ޿ޔᧄ⎇ⓥߩടᾲ

᳇ᵹߪᐔဋ႐ߦߪᶋജߩᓇ㗀߇⷗ࠄࠇߥ޿ޕߒ߆ߒޔߖ ࠎᢿੂᵹਛߢߪޔᩰሶ࡮ബ⿠ੂᵹ႐ߣ߽ㅦᐲ൨㈩ߩᄢ߈ ߐߦᲧ଀ߒߡޔᐔဋ᷷ᐲಽᏓߦ㕖ኻ⒓ᕈ߇⃻ࠇޔࡇ࡯ࠢ

૏⟎߽㋦⋥ਅะ߈߳⒖ⴕߒޔㅦᐲߖࠎᢿߩᓇ㗀߇⷗ࠄࠇ ࠆޕᩰሶੂᵹ႐ߩ Case1, 2, 3 ߢߪޔ x/d=200 ߹ߢ᣿⏕ߥ ࡇ࡯ࠢ߇⏕⹺ߢ߈ࠆߩߦኻߒޔബ⿠ੂᵹ႐ߩ Case4, 5, 6 ߢߪ㋦⋥ᣇะߦᄢ߈ߊᐢ߇ࠆޕߎߩߚ߼ޔബ⿠ੂᵹ႐ߢ ߪޔ x/d=200 ߦ߅ߌࠆ᜛ᢔଥᢙ K ߇ K ѳ 149~405 cm

/s ߣ㕖Ᏹߦᄢ߈޿᜛ᢔ⢻ࠍ᦭ߒߡ޿ࠆޕ

࿑ 2 ߩᐔဋ᷷ᐲಽᏓߩᮡḰ஍Ꮕߢਈ߃ࠄࠇࠆ᜛ᢔ᏷ǻ ߣ᡼಴ࡄࠗࡊౝᓘ d( ೋᦼ᜛ᢔ᏷ ) ߩᵹࠇᣇะᄌൻࠍ࿑ 3 ߦ

␜ߔޕᩰሶੂᵹ႐ߢߪޔੂᵹ႐ߩᮮᣇะࠗࡦ࠹ࠣ࡜࡞ࠬ

ࠤ࡯࡞ L

ߣ d ߩᲧ߇ L

/d ѳ 2.0 㨪 2.4 ߢ޽ࠆߚ߼ޔੂᵹ

᷵߇ࡊ࡞࡯ࡓࠍⰬⴕߐߖߕޔǻо x

ߩ㐳ᤨ㑆᜛ᢔ႐ߣ ߥࠆޕ৻ᣇޔബ⿠ੂᵹ႐ߢߪ L

/d ѳ 8.7 㨪 14.4 ߦ㆐ߒޔ ᄢⷙᮨੂᵹ᷵ߦࠃࠅࡊ࡞࡯ࡓߩⰬⴕㆇേ߇ᵴ⊒ߣߥࠅޔ ǻо x ߩ⍴ᤨ㑆᜛ᢔ႐߇ታ⃻ߐࠇߡ޿ࠆޕߒ߆ߒޔǻѩ L

ߦ㆐ߔࠆߣޔߘࠇએ㒠ߪᄢⷙᮨ߽᷵ࡊ࡞࡯ࡓߦౝ൮ߐࠇ ࠆࠃ߁ߦߥࠆߚ߼ޔ㐳ᤨ㑆᜛ᢔ႐߳⒖ⴕߔࠆߣ⠨߃ࠄࠇޔ ᄢⷙᮨ᷵ߩࠬࠤ࡯࡞߇᜛ᢔ႐ߩᐔဋ⊛ᐢ߇ࠅࠍ᳿ቯߔࠆ

㊀ⷐߥࡄ࡜ࡔ࡯࠲ߢ޽ࠆߎߣ߇ಽ߆ࠆޕ

ߎߎߢߪ࿑␜ߒߥ޿߇ޔ᷷ᐲᄌേߩ㑆ᰳ₸ I

ߩ㋦⋥ᣇ ะಽᏓߪޔᩰሶੂᵹ႐ߢߪบᒻ⁁ߩಽᏓߣߥࠅޔᐔဋ᷷

ᐲಽᏓห᭽ޔࡇ࡯ࠢ૏⟎߇ਅะ߈ߣߥࠆߩߦኻߒޔബ⿠

ੂᵹ႐ߢߪ x/d=40 ߆ࠄਛᔃゲߢ߶߷ኻ⒓ߥࠟ࠙ࠬ⁁ߩ ಽᏓࠍᒻᚑߒߡ޿ࠆޕߎࠇߪޔࡊ࡞࡯ࡓߪㅦᐲ൨㈩ߦࠃ ࠄߕޔ߶߷⌀ߞ⋥ߋߦᵹਅߔࠆ߇ޔੂᵹ႐ߩᄢⷙᮨ᷵ࠬ

ࠤ࡯࡞ L

, L

߇਄ᣇะߦะ߆ߞߡჇᄢߒޔ หᤨߦ᜛ᢔ⢻

߽ᄢ߈ߊߥࠆߚ߼ޔᐔဋ᷷ᐲಽᏓߩࡇ࡯ࠢ૏⟎߇ਅᣇะ

߳⒖േߔࠆߣ⠨߃ࠄࠇࠆޕ࿑ 4 ߦ␜ߔᐔဋ᷷ᐲߩࡇ࡯ࠢ

૏⟎ߦ߅ߌࠆ㑆ᰳ₸ I

ߩᵹࠇᣇะᄌൻߪޔᩰሶੂᵹ႐ ߢߪ߶߷ I

ѳ 1.0 ߢ޽ࠆߩߦኻߒޔ R

߇ᄢ߈޿ Case6 ߢߪᕆㅦߦᷫዋߒޔ x/d=200 ߦ߅޿ߡ I

ѳ 0.25 ߹ߢᷫዋ ߒߡ޿ࠆޕബ⿠ੂᵹ႐ߢߪᄢⷙᮨ᷵ߦࠃࠆࡊ࡞࡯ࡓߩⰬ ⴕㆇേ߇ⴕࠊࠇࠆߎߣߦട߃ޔ ࿑ 4 ߦ␜ߔࠃ߁ߦޔ L

, L

߇ᵹࠇᣇะߦ߽Ⴧടߔࠆߚ߼ޔਅᵹ߶ߤࡊ࡞࡯ࡓߩⰬⴕ ㆇേߩᝄ᏷߇ᄢ߈ߊߥߞߚߎߣ߇ᓇ㗀ߒߡ޿ࠆޕ

4. ⚿⺰

(1) ബ⿠ੂᵹ႐ߢࡊ࡞࡯ࡓߩⰬⴕㆇേ߇ᡰ㈩⊛ߥ⍴ᤨ㑆

᜛ᢔ႐߇ታ⃻ߐࠇߚޕ (2) ࡊ࡞࡯ࡓߩ㋦⋥ᣇะߩᐢ߇ࠅ߇ޔ ᮮᣇะࠗࡦ࠹ࠣ࡜࡞ࠬࠤ࡯࡞ߣห⒟ᐲߣߥࠆߣޔ㐳ᤨ㑆

᜛ᢔ߳ߣ⒖ⴕߔࠆޕ (3) ㅦᐲߖࠎᢿߦࠃࠄߕޔࡊ࡞࡯ࡓߩ Ⱜⴕㆇേߩ㊀ᔃߪ⋥ㅴߔࠆ߇ޔਛᔃゲࠃࠅ㜞ㅦ஥ߢࠗࡦ

࠹ࠣ࡜࡞ࠬࠤ࡯࡞ L

, L

߇ᄢ߈ߊߥࠆߚ߼ޔ ᐔဋ᷷ᐲߩ

㋦⋥ᣇะಽᏓ߇ૐㅦ஥߳߭ߕߺޔㅦᐲߖࠎᢿߩᓇ㗀߇⃻

ࠇࠆޕ (4) ᐔဋ᷷ᐲߩ㋦⋥ᣇะಽᏓߩࡇ࡯ࠢ૏⟎ߦ߅ߌࠆ 㑆ᰳ₸ I

ߩᵹࠇᣇะᄌൻߪޔੂᵹ࡟ࠗࡁ࡞࠭ᢙ R

ߦᒝ ߊଐሽߒޔ R

߇ᄢ߈޿߶ߤᷫ⴮₸߇ᄢ߈޿ޕ (5) ੂᵹ႐ߩ

⛔⸘㊂߇ࠬࠞ࡜࡯႐ߩ᜛ᢔߦᒝ޿ᓇ㗀ࠍਈ߃ࠆޕ ᣣᧄቇⴚᝄ⥝ળ⎇ⓥ⾌⵬ഥ㊄ၮ⋚⎇ⓥ (c)No.17560145 ߩេഥࠍฃߌߚޔߎߎߦ⻢ᗧࠍ⴫ߔࠆޕ

ෳ⠨ᢥ₂

1) H. Makita: Fluid Dyna. Res., 8, (1991), pp.53-64.

2) ⫣↰ , ૒ޘ , 㘵↰ , ⨃ጊ : ᯏ⺰ B, 56, (1990), pp.

388-395.

3) ⫣↰ , ች↰ , 㑐ਅ : ᯏ⺰⻠ , 05-32, (2005-10), pp. 250.

4) ⫣↰ , ⼱ญ , 㑐ਅ : ╙ 4 ࿁ᣣᧄᵹ૕ജቇળਛㇱᡰㇱ⻠

Ṷ⺰ᢥ㓸 , (2006-11), pp. 21-22.

5) ⫣↰ , ᫪ , Ỉ↰ : ᯏ⺰ B, 56, (1992), pp. 90-97.

0

x/d=100

x/d=200 x/d=40

0.3

pr ob ab ili ty d en si ty fa nc tio n

0.3 0 0.3

0

-24 -16 -8 y/d 0 8 16 24

࿑ 2 ᐔဋ᷷ᐲߩ㋦⋥ᣇะಽᏓ

٤ , ٌ , غ㧦 Case1, 2, 3 ٨ , ً , ع : Case4, 5, 6

0 100 200 300 350

0 5 10

x / d

㱟 / d

15 _Case6

Case5 Case4

Case3 Case1, 2 L

/d

࿑ 3 ᜛ᢔ᏷ǻߩᵹࠇᣇะᄌൻ

٤ , ٌ , غ , 㧦 Case1, 2, 3 ٨ , ً , ع : Case4, 5, 6

0 100 200 300

x / d 0

0.25 0.75

intermittency I㱔p

1.0

0.5

Lux , Lvx×10-1 [m]

0 0.25 0.75 1.0

0.5

࿑ 4 ࡇ࡯ࠢ૏⟎ߦ߅ߌࠆ㑆ᰳ₸ I

ߩᵹࠇᣇะᄌൻ I

; ٤ , ٌ , غ , 㧦 Case1, 2, 3 ٨ , ً , ع : Case4, 5, 6

L

, L

; ٠ , Ӡ : Case3 ٟ , ٻ Case6

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