Chapter 3 KTTK

7/30/2019 Chapter 3 KTTK

1/21

Presented By

Harry Mills /PRESENTATIONPRO

Chng : NG HC CHT LNG

3.1 Khi nim chung

NI DUNG CHNH

3.2 Cc khi nim c s

3.3 Chuyn ng c th

3.4 Phng trnh lin tc

K thut thu kh
http://www.presentationpro.com/power_designs.aspxhttp://www.presentationpro.com/power_designs.aspxhttp://www.presentationpro.com/power_designs.aspxhttp://www.presentationpro.com/power_designs.aspx


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3.1.1 Nhim v

3.1 KHI NIM CHUNG

ng hc chtlng nghin cuchuynngcacht lng v ngdng cc quy

lut vo thctsnxut

K thut thu kh


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3.1.2 Cc gi thit

3.1 KHI NIM CHUNG

K thut thu kh

Coi chuyn ng ca cht lng l lin tc

Phn bit p sut thu ng v p sut thu tnh

Coi cht lng ng khng nn c: =const


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3.2.1 ng dng

3.2 CC KHI NIM C S

K thut thu kh

Trong mttrng vc tvntc, ta c th tm cmtng

cong sao cho n tiptuynvi cc vc tvntc qua cc imca n. ng cong gi l ng dng
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3.2.1 ng dng

3.2 CC KHI NIM C S

K thut thu kh

zyx u

dz

u

dy

u

dx0rdurd//u Phng trnh ng dng

Cc ng dng khng ct nhau


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3.2.2 ng dng

3.2 CC KHI NIM C S

K thut thu kh

Cc ng dng ta lnmt vng kn v cngnh ta c mt ngdng. Cht lng khngth xuyn qua ng dng.


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3.2.3 Dng nguynt

3.2 CC KHI NIM C S

K thut thu kh

Bn thn khicht lngchy trongng dng gi l dng nguyn t

L tp hp v s dng nguyn t.

3.2.4 Dng chy

3.2.5 Mt ct t

Din tch mt ct t dng nguyn t: k hiu dL mt ct vung gc vi tt c cc ng dng ca dng nguyn t.

Din tch mt ct t dng chy: L mt ct vung gc vi tt c cc ng dng ca dng chy


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3.2.6 Chu vi t: k hiu (m)

3.2 CC KHI NIM C S

K thut thu kh

L chiu di ontip xc giachtlng v thnh rncamtctt

L t s gia din tch mtct t v chu vi t :

3.2.7 Bn knh thu lc: k hiu R (m)

3.2.8 Vn tc thc: k hiu (m/s)

L vn tc chuyn ng ca phn t cht lng qua mt im c nh

R

u


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3.2.9 Lu lng

3.2 CC KHI NIM C S

K

thut thu

kh

Lulng dng nguynt: th tch chtlngchyqua din tch mtcttd ca dng nguyn ttrong mt n v thi

gian.

Lu lng dng chy:Th tch cht lng chyqua din tch mtcttdng chy trong mtn v thi gian

Q (m3

/s, l/s...)dQ = u.d (m3/s, l/s... )

d.udQQ


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3.2.10 Vn tc trung bnh: k hiu v (m/s)

3.2 CC KHI NIM C S

K thut thu kh

Coi miimthuc c cng vntc trung bnh ca ton mt

ct sao cho

d.u.vQ


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3.3.1 Hm dng v th vn tc

3.3 CHUYN NG C TH

K thut thu kh

Kho st chuynng trong mtphng Oxy

a vo hm :(x,y) v (x,y) sao cho tho mn iu kin:

xyu

yx

v

: Hm dng; : Th vn tc .

T phng trnh ng dngv

dy

u

dxdt

0v

ddy

ydx

xudydx

Phng trnh ng dng c dng: = Const.


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3.3.1 Hm dng v th vn tc

3.3 CHUYN NG C TH

K

thut thu

kh

Tng t ta c = Const biu din h ng ng vn tc

Cc ng dng v ngngthtrc giao vi nhauv tnhnghaca v :

0

yyxx

( iukin Csi- Riman).


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3.3.2 Tnh lu s vn tc v lu lng

3.3 CHUYN NG C TH

K

thut thu

kh

Tnh lu s vn tc trn cung AB

B

Ayx

B

AAB )dyudxu(uds

B

AAB dy

ydx

x)(

)()( ABdB

AAB


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3.3.2 Tnh lu s vn tc v lu lng

3.3 CHUYN NG C TH

K

thut thu

kh

Tnh lu lng q

B

Ayx

A

B

n )dxudyu(dsuq

B

A

)dxx

dyy

(q

)()( ABdqB

A


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3.3.3 ng xoy v ng xoy

3.3 CHUYN NG C TH

K

thut thu

kh

Chuyn ng quay ca miphn t cht lng xung quanh mt

trc quay tcthii qua n cgi l chuynng xoy


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3.3.3 ng xoy v ng xoy

3.3 CHUYN NG C TH

K

thut thu

kh

Vctvntc gc trong chuynng xoy

urot2

1

ng cong tip xc vi vect vn tc gc gi l ng xoy

Cng ca ng xoy duroti n .

Phng trnh ng xoyzyx

dzdydx


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.3.4 Th phc w(z), vn tc phc w(z)

3.3 CHUYN NG C TH

K

thut thu

kh

Giathvntc v hm dng c quan h sau

xy

yx

Hm s phc w(z) xc nh bng cng thc:w(z)= +i

Trong : z= x+iy

Vn tc phc: yx iuux

ix

zw

)(' uuuzw yx

22)('


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3.4.1 Dng tng qut (Dng Euler)

3.4 PHNG TRNH LIN TC

K

thut thu

kh


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3.4.1 Dng tng qut (Dng Euler)


K

thut thu

kh

0.1

z

u

y

u

x

u

dt

d zyx

0dtdm 0)(

dtVd 01.1 dt

VdVdt

d

dxdydzdtz

u

y

u

x

uVd z

yx )(

Mt khc:


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3.4.2 Phng trnh lin tc i vi dng nguyn t


K

thut thu

kh

constdQdudududu 22112211.

Kho st khi cht lng trong

dng nguyn tgia 2 mtct1-1 v 2-2:

Sau thi gian dt: lng chtlng i vo 1-1 v i ra 2-2

bng nhau theophng trnh:


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2

1


3.4.3 Phng trnh lin tc i vi dng chy n nh


K

thu

t thu

kh

21

2211

dudu

2211 vv

21 QQ

Tch phn 2 vphng trnh trn:

constQ

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Chapter 3 KTTK