Trao ddi hqc thudt & Thdng tin Khoa hgc Cdng nghe
TINH LlTU BIEN CUA CHAT LUU PHI NEWTON GIA CO SQl
TS. PHAN VAN TIEN Khoa Xay dung Bgi hgc Vinh
Tdm tdt: Bdi bdo ndy trinh bdy nghiin cuu thuc nghiem vi dnh hudng ciia sgi tdi tinh luu bien cua chdt luu phi Newton Hai moi Irudng chdt luu dd dugc sii dung- chdt luu tuy?t dot nhdt vd chdt luu nhdt deo co irng xir chdy long. Ba logi sgi da dugc su dung Kit qud cho thdy tinh luu hiin cua chdt luu thay dot rdt ro ret theo hdm lugng sgi, 1/4, trong khi dnh hudng ciia 2 logi sgi 235/075 vd 243/125 ldi tinh tuu biin la rdt nhd.
Summary: This paper presents an experimental stu<fy on the influence of fibers on the rheological properties of non-Newtonian fluids. Two types of fluids matrices, shear thinning fluid and yield sires shear thinning fluid were considered. Three types of fibers were used The results indicates that the rheological parameters are strongly affected by the contents of fiber 2.1/4, while fibers 235/075 and 243/125 only give small influences on the rheological behavior.
I. D ^ T V A N DE
Sgi t h u d n g d u g c them vdo cdc chdt luu de cai thien cac cdc tinh chdt ciia nd tiiy thudc vdo mye dich sti d u n g c u a nd. Hieu qud s u d u n g sgi phu thudc vdo ti le chieu d d i / d u d n g kinh, hinh ddng ciia sgi cung n h u sy phan bd sap xep ciia sgi trong vat lieu. Sy sap x e p cua sgi, g d m vj tri sap xep v a h u d n g sap xep cua nd trong vdt lieu, can phdi d u g c nghien c u u kT l u d n g khi vat lieu d trang thdi long. Trudc khi qua trinh ddng dac xdy ra, cac ting xir vat ly cita vat I ieu cd t h e d u g c md td bdng cdc yeu td luu bien n h u ngudng chay, dg nhdt,... Do dd, myc dich c u a nghien ciiu nay Id xdc dinh dnh h u d n g ciia hdm lugng s u dung cita cae logi sgi khdc nhau tdi cac yeu td nay.
T r u d c day d a eo nhieu nhd khoa hge trien khai cdc nghien ciru ly thuyet va t h y c nghiem ve anh h u d n g ciia sgi tdi u n g x u luu b i l n eiia c h i t luu, birig each gia dinh c h i t luu Id chat luu Newton [1-3]. T u y nhien, cd r i t t't cdng bd v l dnh h u d n g c u a sgi tdi tinh luu b i l n c u a c h i t luu phi Nevrton [8]. M u c tieu eiia nghien cdu ndy la bdng p h u a n g phap t h u c n g h i e m , k i l m tra u n g x u luu b i l n ciia chat luu phi Newton khi gia cd bang cae logi sgi khac nhau. Ket q u a cita nghien cuu se gdp phan gitip hieu b a n ve iing x u luu bien ciia c h i t tuu phi Newton khi gia cd sgi c u n g n h u vai trd ciia cae logi sgi khdc nhau tdi u n g xu luu b i l n ciia c h i t luu phi N e w t o n .
I I . V A T L I E U V A PHUOTVG P H A P T B I N G H I E M 2 . 1 . V a t lieu t h i n g h i e m
Hai mdi t r u d n g chdt luu phi Newton d a d u g c s u dung: chat luu tuyet ddi nhdt cd u n g x u
260 Tgp chi KHOA HOC GIAO THONG VAN TAI S6 43 - 09/2013
Trao ddi hoc thugt & Thong tin Khoa hoc Cong nghe chay long (chit lira Xanthane) va chat lini nhcrt deo co trng xii chay long (chit liru bentonite).
Tinh litu biSn cua chat lira Xanthan da dugc nghien ciiu va cong b6 boi Song [7], cho thjy img xii litu bien ciia chit liru Xanthan khi ham luong ctia Xanthan <0.4% la tuyet doi nhot phi tuyen lhu6c loai chay long. Cong thiic ciia dung djch Xanthan gum diing trong nghien cihi nay dirijc mieu ta trong bang 1.
Thanh phSn
Ham lirong
% theo khoi Immg
Nuac cat
20
Glycerin
80
Xanthan 0 0,05
0,1 0,2 0,5
Bine I. Conf' thuc chdt lieu Xanthan Sgi (2.1/4; 235/075; 243/125) 0 0,1 0.2, 0,4 0,8 1
-
1,5 2
- -
•
-
Thanh phan Ham lugng %
theo khoi lirgng
Dung djch 20% nuoc cSt 80% glycerin 100% nudc cat
Bentonit 0,2 0,5 1 2
Bdng 2. Conn thiec chat luy bentonit Sgi (2.1/4; 235/075; 243/125) 0 0,1 1 0,2 0,4 0,8 1 1,5 2
Bang 3. Kich thuoc va tl le chiev dai/duang kinh c
Chieu dai (^im) Ducrng kinh (jtm/s) Ti le chieu dai / duong kinh
Sgi 2,1/4 4000
21 190,48
Sgi 235/075 235
75 3,13
HO ba logi sai su dung Sgi 243/125
243 125 1,944 ChSt luu nhdt deo phi tuySn co ling xir thuoc loai chay long dugc sii dung la moi trudng djlng hjt CO chlia bentonit. Cac nghien ciiu da cong bo vj chSt luu bentonit [6, 9] da chi ra rang tag xii luu biSn cua chit luu bentonit la Newton khi ham lugng bentonit thip va phi Newton khi ham lugng bentonit vugt qua mgt gia trj nhit djnh. 0 day ham lugng bentonit dimg tir 0,2- 2%. Ham lugng phin tram theo kh6i lugng cac thanh phin ciia chit luu bentonit ditgc mieu ta trong bang 2. Cac loai sgi co hinh dang, kfch thugc va dugng kinh nhu trong bang 3, 2.2. Thilt bi thi nghiem
Tinh luu biSn dugc xac djnh bang may do luu biSn, sir dung bg thiet bi co kich thuoc va hinh dang nhu hinh 1. Thiet bi nay da dugc dimg dl do tinh luu biSn boi rat nhieu tac gia va Tap chi KHOA HQC GIAO T H 6 N G VAN TAI So 43 - 09/2013
261
Trao ddi hgc thudt & Thdng tin Khoa hgc Cong nghe
dugc chung minh la phii hgp vdi chit luu dang hat vi nd han chl toi da su trugt tudng (wall- slippage) vd hien tugng cat cue bd mau thi nghiem [4].
Hinh I. Mdy do luu biin vd hi thong thiil hi do. a) Vane, b) Tru 2.2. Phirong phap thi nghiem
0.05% Xanihaii; 1.5% •an 2,1/4
•mm giau (i) V5TI i6c bl^B dang (I/s) Hinh 3. Quan hi irng sudi iheo thai gian va kit qua: do thi ung .\udl-vgn ldc biin dang Tinh luu bien dupc do bang phuong phdp kiem soat img suat. Nhu da thay tren hinh 3, ung suit tac dyng len mau Ihi nghiem tang din, khi vupt qud ngudng chay. mdu bdt dau bj pha huy va ddng chdy bat diu xuit hien. van tdc bien dgng tang dan (chat luu chuyln tu trgng thai tmh sang trang thai dpng), Khi van toe bien dang du Idn de xac dmh rang ung suat tdc dung da vugt qua ngudng chay. ung suat dugc giam dan dan ve gia tri 0. chdt luu chuyen tu trang thai dgng sang trang thai tmh.
Bang cdch quan sat dudng cong quan he ung sudt-vdn tde bien dgng thu duge, cdc gia trj dac trung cho tinh luu bien ciia chat luu, nhu ngudng cha\, do nhdi,... se dugc xac djnh bdng mo hinh iing xii luu bien Herschcl-Bulkley, Day la md hinh rat phii hgp de mieu ta ehinh xac ling xu luu biln phi tuyin cua vat lieu nhdt deo [5].
262 Tap chi KHOA H O C GIAO THONG VAN TAI So 43 - 09/2013
Trao ddi hqc thudt & Thdng tin Khoa hqc Cdng nghe
III. KET QUA THI NGHlfM
3.1 Ngirdng chay cua chat Iwu khi gia co soi
Ham liryng sgi {%) Ham lirgng siji (%) Hinh 5. Quan hi ngudng chdy - hdm luang spi cua chdi luu xanthan
2% Bentonite 0.5%
•U-hbtttiSKni -*-fiber 2 « 125
trntCtT- • — • Bentonite
/ \
Ham inmg sol (•/.) Ham limis sfi ("/») Hinh 6. Quan he ngudng chay - ham luong soi cua chat luu Ijentonll Tir kit qua thi nghiem, d6 thi ghi lai quan he ngugng chay va ham lugng sgi cua cac chat luu CO ham lugng Xanthan khac nhau dugc biSu thi tren hinh 5. Chung ta co the thay rang ngirSng chay cua chit luu tang theo sir tang ciia ham lugng sgi. cu the: Vgi sgi 2.1/4, a ham lugng Uiip (<0,4%), ngugng chay tang vira phai theo su tang cua ham lugng sgi. Khi ham lugng sgi vugt qua 0,4%, nguong chay tang vgt ro ret theo ham lugng sgi. Bilu nay chi ra rang doi voi sgi 2,1/4, anh hucmg cua sgi toi nguong chay ciia chat luu chi ro ret khi dugc s j dung vgi ham lirgng cao. Viec ton tji mgt gia tri ham lugng sgi ma khi ham lugng sgi su dung virgt qua do, anh huong cua sgi toi tinh luu biln la ro ret, da duoc phat hien va cong b6 gin day boi Kaci [4].
T?p chi KHOA HOC GIAO THONG V .AN TAI S6 43 - 09/2013 263
Trao ddi hoc thudt & Thdng tin Khoa hqc Con^ ngrtK
Vdi sgi 235/075 vd 243/125, chi khi ham lugng sgi vugt qud 1%, ngudng chdy mdi tdng khi ham lugng sgi tang, Tuy nhien sir tang nay la rat khdng rd rang.
Ddi vdi chit luu bentonit, quan h$ nguong chay - ham lucmg sgi dugc bieu thj tren hinh 6.
Tucmg tu nhu trudng hgp chdt luu Xanthan, ngudng chay ctia chdt luu khi ditng sgi 2,1/4 cao han rat nhilu so vdi ngudng chay cua chdt luu khi diing 2 laai sgi cdn Iai, va sir khac biet nay cdng rd ret khi hdm lugng sgi tang Ien.
3.2. Do nhdt cua chat luu khi gia co spi
0 . 1 % X w t h a n 0.5% Xctfithan
^ 30
«-flb*rZ36«TS -«-tlber 213/125
eo
• ^
eu
•E ^0 o
20 - ^ f l B a r 2 , i r 4
«~ftbar235«TS -•-fiber 243'126
-•"•iS-.^'T-^"--*—' ^
as 25 05
Hdm lirgng sqi (%) HSm lirgng soi (%) Hinh 7. Quan hi dp nhai - hdm luang sgi cua chdt luu Xanthan
a5% Bentonite 2% Bentontte
. • - riBer Z3B/QTG - * - f i b e r 20/1Z9
5 40
Ham Itfffug sgi (%) Him lirgng sgi (%) Hlnh 8. Quan h? dp nhdt - hdm lugng sai cua chdi luu bentonit
Quan he dp nhdt ciia chat luu Xanthan vd bentonit theo ham lugng sgi dugc bi^u thj tren hinh 7 vd 8. Do thj ndy sgi tuang tu nhu dd thj dnh hudng cua ngudng chdy d hinh 5 vd 6, Cu Xhi: sgi 2,1/4 cd anh hudng rdt ldn tdi do nhdt so vdi 2 loai sgi cdn lai. Ddng thdi tdn tai mgt gia trj ham lugng sgi (0,4%) md khi v u 0 qua nd, sir phu thugc cua do nhdt tdi bam lugng sgi ldn hem hdn. Dieu nay cung da dugc cong bd bdi Kaci [4]. Hai loai sgi cdn lai cd rat it tdc dung tdi
264
Tap chi KHOA HOC GIAO T H O N G VAN TAI So 43 - 09/2013Trao ddi hqc thudt & Thdng tm Khoa hoc
dp nhdt, cd nghia Id siic khdng cdt ciia chdt luu dung sgi 2,1/4 Idn han rdt nhilu so vdi chdt luu diing sgi 235/07 vd243/125.
IV. KET LUAN
- Ngudng chdy va do nhdt ciia chat luu tang theo hdm luong sgi, tuy nhien muc dnh hudng cua cdc loai sgi tdi tinh luu biSn Id rat khdc nhau: Vdi soi 2,1/4, ti le chilu ddi/dudng kinh 190,48, ngudng chdy va dp nhdt nay tang tu td tdi khi ham lugng sgi vugt qua mpt gia trj nao do (tiiy thuoc vao chat luu), Khi vugt qua gid trj nay, ham lugng soi cd dnh hirdng ldn, rd ret tdi tinh luu bi^n ciia chdt luu. Con sgi 235/075 vd 243/125 co ti Ie chilu dai/dudng kinh nhd (3,13 va 1,944), anh hudng ciia ham lugng sgi tdi tinh luu biln chi rd rerihi ham lugng sgi vugt qua 1%.
- Sgi 2,1/4 cd dnh hudng ldn tdi tinh luu biln, trong khi su cd mat ciia 2 loai sai cdn lai trong chat luu chi cd anh hudng rdt nhd. Dieu ndy chi ra tdm quan trong cita ti \i chilu dai/ducmg kinh ciia sgi tdi tinh luu bien ctia chdt luu phi Newton.
T^ilifu Iham khao
[I], Balchelar. G - The stress generated in a non dilule suspension of elongated particles by pure straining moUon.
Journal ofFIuid Mechanics. 46. 1970. 813-829
[2|. Dinh SM and Amslrong RC • A rheological equation of slaie for semi-concentrated fiber suspensions, .loumal of Rheology. 28, 1984.207-227
|3] Jelfery. G. -The motion of ellipsoidal immersed particles in a viscous fluid. Proceding Royal Society of London, AI02, 1922,161-179,
14). A Kaci el al. - Adhesive and rheological properties of fresh fiber reinforced mortars. Cement and Concrete Composites. 33. 20t 1.218-224,
|5|. Cao Xudn Phong el at.- U'ng xir luu bien va mo hinh (hi nghiem chay xoe cua be long tir diim Ifin - NCKH Tnrcmg DH Ki6n true TP HCM. 2009,
|61. Laribi. S. el al - Comparative yield stress dciermination for pure and interstratified smeclUe ciays. Rheologica Acta. 44. 2005. 262-269
171. Song. A H' el al. - Rheology of concentrated xanthan gum solutions- steady shear flow behaviour. Rheologica Acta, 7(2). 2006. 129-138
IS), 1/) • Tsebrenlio el al. • Fracture of ullraline fibers in the flow of mixtures of non-newlonian polymer mells.
Joumal of Non-Newtonian Fluid Mechanics. 31. 1989. 1-26.
|9|. Yah. H and Baclmam, L - UllraKtructurc and flow behaviour of colloidal smectite dispersions. Joumal of Colloid and Interface Science. I26( 1). 1988, 278-291 •
Ph^n bien: GS, TS. Pham Duy Huu
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