chapter 4 kttk

7/30/2019 Chapter 4 KTTK

1/23

Presented By

Harry Mills /PRESENTATIONPRO

Chng Thu ng lc hc

Thit lp phng trnh vi phn chuyn ng

Ni dung chnh

Vit cho dng nguyn t cht lng thc

Vit cho dng nguyn t cht lng l tng

Phng trnh Bernoulli

ng dng phng trnh Bernoulli

Vit cho dng chy cht lng thc

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


2/23

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Chng Thu ng lc hc

4.1 PHNG TRNH VI PHN CHUYN NG CACHT LNG L TNG

4.1.1 Dng LE

K thut thu kh

Phng trnh le ng

gradpFdt

ud

1


3/23

Presented By


Chng Thu ng lc hc


4.1.2 Dng Lmb- Gromeca

K thut thu kh

xww

xvv

zuw

yuv

xuu

tu

xp

1 X -

)()()(1

x

w

z

uw

x

v

y

uv

x

ww

x

vv

x

uu

t

u

x

p

X -

wvuxt

uxp

yz

2.2)2

(12

X -

)2.(2)2

(1 2

vwu

xt

u

x

pzy

X -

Ta xt phng trnh hnh chiu ln trc Ox


4/23

Presented By


Chng Thu ng lc hc


4.1.2 Dng Lmb- Gromeca

K thut thu kh

ut

uuPgradF

2)

2(

2

- Tngtchiu ln cc trc Y,Z ta c:

- Vit dui dng vect:

)2.(2)2

(1

2

wuu

yt

v

y

pxz

Y -

)2.(2)2

(1

2

uvu

zt

v

z

pyx

Z -


5/23

Presented By


Chng Thu ng lc hc

4.2 CC DNG PHNG TRNH BERNOULLI CHOCHT LNG L TNG

K thut thu kh

const 0

t

g

upz

g

upz

22

2

222

2

111

Vichtlng l tng (khng c tnh nht).

Dng tch phn caphng trnh NavierStoc viiukin :

;

(Lc khi ch l trng lc, chn trc z hng ln trn)

Phng trnh Bernoulli c dng :

; X =Y=0 ; Z =-g


6/23

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Kho st mt phn t hnhhp cht lng chuyn ngvi vn tcLc tc dng ln khichtlng :

Chng Thu ng lc hc

4.3 PHNG TRNH VI PHN CA CHT LNGTHC

K thut thu kh

4.3.1 Dng ng sut

u

Thnhlpphngtrnh vi phnchuynng.

+ Lc qun tnh :dt

udmFqt .

+ Lckhi : Fm.P+ Lc mt : (6 lc mt)


7/23

Presented By


Theo nguyn l Dalambe

Chiu cc lc ln trc ox:

Chng Thu ng lc hc


K

thu

t thu

kh

4.3.1 Dng ng sut

Thnhlpphngtrnh vi phnchuynng.

Fqtx+ Fx + Px - Px = 0

dt

du

xyz

pX xxz

xyxx

)(

1

0.....)(...

dt

dudzdydxdzdydxzyx

pXdzdydx xxz

xyxx

0'. xxqt PPFmF


8/23

Presented By


Tng t theophng y v phng zta c: phngtrnh vi phn chuynng ca cht lng

thcdngngsut

Chng Thu ng lc hc


K

thu

t thu

kh

4.3.1 Dng ng sut

dt

du

xyz

pX xxz

xyxx

)(1

dt

du)

xzy

p(

1Y

yy xy zy y

dt

du

xyz

pZ zzxzyzz

)(1


9/23

Presented By


Chng Thu ng lc hc


K

thu

t thu

kh

4.3.2 Dng Navie Stock

udivx

uxpX

dtdu

xx

311

udivy

uy

pY

dt

duy

y

3

11

udivz

uz

pZ

dt

duz

z

3

11


10/23

Presented By


Chng Thu ng lc hc

4.4 CC DNG PHNG TRNH BERNOULLICHO CHT LNG THC

K thut thu kh

4.4.1 Vit cho dng nguyn t

)(3

1udivgradugradpF

dt

ud

Phng trnh Navie Stock vit di dng tng qut nh sau:

i vi cht lng khng nn c =const, l cht lng l tng ( =0)

gradpFdt

ud

1 Phng trnh le


11/23

Presented By


Chng Thu ng lc hc


K thut thu kh


Bin iphng trnh trn ta cphng trnh Bernoullivitcho dng nguyn tcachtlngl tngnhsau:

g

upz

g

upz

22

2

222

2

111

Phng trnh Bernoulli vit cho dng nguyn t cht lng thc:

21

2

222

2

111 '

22 wh

g

upz

g

upz


12/23


13/23

Presented By


Chng Thu ng lc hc


K thut thu kh


nghaphngtrnh Bernoulli.

nghannglng

: V nng n vz

p: p nng n v

pz : Th nng n v

: ngnngnvg

u

2

2


14/23

Presented By


Chng Thu ng lc hc


K thut thu kh

4.4.2 Vit cho ton dng

Vitphng trnh Bernoulli cho dG trng lng sau

tch phn trn tonmtct: dG =dQiukinthitlpphngtrnh:

+ Dng chy l dng nnh (Q =Const)

+ Chtlng khng nn c (=Const)+ Lckhi tc dng ln chtlngchl trnglc (Z =-g)


15/23

Presented By


Chng Thu ng lc hc


K thut thu kh


dQhdQg

udQpzdQg

udQpz w 212

222

1 1

211

1 '2

)(2

)(22

Qp

zdQp

z

)()(

Qg

vdQ

g

uTtt

22

22Trong :

QhdQh ww

2121'


16/23

Presented By


Chng Thu ng lc hc


K thut thu kh


21w

2

2

2

2

2

2

1

1

1

1 hg2

vpz

g2

vpz

Phng trnh Bernoulli vit cho on dng chy c dng nh sau:

:phthuc vo chchy.+ Chytng=2+ Chyri = 1,05 1,1 ( Thng thnglybng 1)


17/23

Presented By


Chng Thu ng lc hc


K thut thu kh

4.4.3 ng dng phng trnh Bernoulli

Phngtrnh Bernoulli lphngtrnh csdngrtnhiugiiquytcc bi ton thulc.sdngphngtrnh Bernoullihiuqu ta cnlu :

Chnmtctsao cho ph hpviiukinlpphngtrnh

Chnmtchun sao cho ph hp.

Vitvip sutg (p suttuytihay p sutd)


18/23

Presented ByHarry Mills /PRESENTATIONPRO

Chng Thu ng lc hc


K thut thu kh


Xc nh cao t bm

Bi ton : Xc nh hs = ?Bit : Q , pck, d(Gi thit h

w1-2 bit)

Bm ly tm

CKK

21

2

2 w

cks h

g

vph


19/23

Presented ByHarry Mills /PRESENTATIONPROK thut thu kh

Nhit (oC) p sut hibo ho (at) Nhit (oC) p sut hibo ho (at) Nhit (oC) p sut hibo ho (at)

-10 0.003 20 0.023 97 0.8970 0.006 25 0.031 98 0.9305 0.009 30 0.042 99 0.964

10 0.012 37 0.062 100 1.00011 0.013 40 0.073 101 1.03712 0.014 60 0.197 110 1.41413 0.015 80 0.467 120 1.95914 0.016 95 0.834 200 15.34115 0.017 96 0.866

Bng lin h p sut v nhit hi bo ho


20/23


Chng Thu ng lc hc


K thut thu kh


122v hhg

ng Pitt


21/23


Chng Thu ng lc hc


K thut thu kh


ng Pitt


22/23


Chng Thu ng lc hc


K thut thu kh


ng Venturi


23/23

Presented ByHarry Mills /PRESENTATIONPROK thut thu kh

chapter 4 kttk

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