Dong luc hoc bay cua khinh khi cau dang dTa Eh'psoid
N g u y e n Minh Xuan*", Ngo Minh Tuin'^', Hoang Anh Tii*^' (I) Hoe viin Ky thudt Qudn sir
(2) Hoe vien Phdng khdng - Khdng qudn
Tdm tia.iBdi viet dua ra nghien ciru vi chi tgo khinh khi cdu (KKC) cd diiu khien - nhirng vdn de quan trgng vd phire tgp cua khoa hoc vd ky thudt. Mgt trong nhirng bdi todn dgc tnrng cdn giai quyet dd Id ddng lire hoc bay KKC.
Abstract:Thls paper gtved the research about making control ellpsoid balloon - the Impotant and complicate problems of science and technics. One of specific problems that need to solve is dynamic of flights of balloon.
1. Dat bai toan /. /. Dgt vdn de
Gan day tai nhieu qudc gia ngudi ta lai quan tam nghien ciiu cac phuang tien bay nhe ban khdng khi. Khac vdi nhung giai doan trude day, cac nha thiet ke ngay nay dinh hudng cac quan tam tdi viec che tao cac khinh khi cau van tai cd kha nang mang cac tai Idn tdi cac viing xa hoac cac vi tri khd tiep can cua hanh tinh. Sy phat trien cua cong nghe may tinh tao kha nang cho cac nha thiet ke nghien ciiu cac dac trung khi dgng lyc bgc, thiet ke va thir nghiem cac md hinh vdi do chinh xac cao. Tinh loan cac tham sd dgng lyc bgc bay, dac biet la tinh toan cac bai toan ve quy dao la giai doan quan trgng trong qua trinh thiet ke. Trong dieu kien nhat djnh bai loan xac djnh cdng suat, cac dac tinh can thiet cho chuyen bay cua khinh khi cau dang dTa elipoid tren co so cac nghien cuu thi nghiem ddi vdi cac dac tinh khi dgng ciia md hinh KKC trong dng thdi khi dgng.
1.2. Xay dung bdi todn
a. Tinh todn cdc tdc do thuc cua md hinh KKC trong che do bay bdng dn lap, tai mot chi do lam viic cua ddng ca.
Md hinh KKC dang dTa elipsoid tao hinh da dugc thiet ke (binh I) va dugc dat trong dng thdi.
Chuyen bay thyc te cua KKC dang dTa trong khi quyen kha pbirc tap. Khi cat canh KKC phai chuyen dgng dudi tac dgng cua lyc nang khi tTnh - theo phuong thang dirng do khi Heli tao nen khi nap vao KKC hoac ket hgp vdi cac dgng co. Ngoai ra khi tao ra gdc nghieng cua dgng ca KKC cd the thuyen dgng vdi quy dao nghieng, cong va quy dao phire khac. Cac gia thiet tinh loan:
- Cac dgng co khdng chuyen dgng va chiing tao ra lyc day & song song vdi vecta toe do bay.
- Cac lyc khi tTnh khdng ddi.
- Cac gdc tan khai thac cua KKC thay ddi trong khoang tir 0-25°.
440 Ddng lue hoc bay cua khinh khi cdu dang dia Elipsoid Tinh toan thyc hien cho KKC dudng kinh 16m, chieu cao 4m, khdi lugng 700kg (khi bay vdi 02 phi cong). Bai toan khao sat d 3 che do bay: cat canh, bay bang va ha dg cao.
Doi vdi KKC thiet ke, bay bang la che do khai thac ca ban ciia KKC. Trong che do dd cd lyc nang khi dgng tac ddng len KKC Ya = Cj^ pV\S
Vdi Cya- he sd lyc nang; p - mat do khong khi d do cao cho trude; V tdc do KKC; S- dien tich viing that nhd nhat KKC; Xg- lyc can chinh dien KKC; G=mg-lyc trgng trudng tac dung len KKC. Mirc tang lyc nang khi tTnh la: AK^^„ = mg - T^,^, , trong dd Yasi-liJ'C nang Asimet hay lyc nang khi tTnh. Gia tri thir nghiem thdi md hinh KKC trong dng thdi khi dgng De tao ra lyc nang khi tTnh ngudi ta nap vao KKC 600m khi Heli. Lyc nang khi dgng dugc tao bdi 3 dgng ca pitton cd lyc day mgt dgngca la 58 kW.
c
,3 L.
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N..~
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Hinh 1: Hinh chiiu 3 mat ciia md hinh Khinh khi cdu thiit ke
Kit qua thir nghiem thdi mo hinh KKC dang dTa trong 6ng khi dgng thi hien trong hinh 2, 3.
Hinh 2: Quan he hisd lire ndng vd gdc Hinh 3: Quan hi hi sd lire ndng vd he sd ('^'^ luc cdn
b. Xdc dinh dgc tinh Idy do cao dn lap
Khi bay theo quy dao nghieng tang din, KKC bi tac dgng bdi cac lye sau: luc nang khi dgng Y^, lyc nang khia tTnh Y^,„ lyc can X^ va lyc diy dpng co Pj,. Liy do cao dac trung bang tdc do ddng khi V, gdc nghieng quy dao 6. He phuang trinh chuyin dgng cua KKC khi lay do cao dn lap, [1]:
r
/ ; ; g c o s 6 ' - r , - y „ „ c o s 6 ' = 0;X^, + mg cos e = P,f,
Vy = r s i n 6 ' ; (1)
dt ' V - ^
'~dt-
vdi dH - muc gia tang do cao, dL - muc gia tang tam xa bay.
2. Giai quyet cua bai toan
a. Xdc dinh cdc tdc do thdng qua tinh todn dgc trung cdng sudt
Tir muc tieu khao sat, phuang trinh can bang KKC cd the vilt: I Ci ~ ^a - Oi
Trong dd P^ - lyc day can thiet. Tir phuang trinh can bang cd the xac djnh tdc do bay bing
KKC, [2]: V,, = J ' : r" = J - : : - ^ (2) C..^pS • yu CyapS • ya
Cdng suat can thilt xac djnh la:
442 Ddng lue hoc bay cua khinh khi cdu dang dia Elipsoid
A^ = {'ng-Y^,„)V,, AK,„K,,,
K K (3)
(f> day K - he s6 chit lugng khi dgng KKC.
Cdng suit hicn cd cua dgng co KKC bang tdng cong suat tren true cua cac canh quat yV(. = n. Nad, n = ^Vr/t " ^° ^^"^ ^°^' ^'^'^' ''°"§ ^^^^ ^^^ '^^^^ ^^'
Cdng suit tuang duong cua dgng ca pitton bang cong suat hieu qua cua dgng eg:
A'td = A'e,H-
Khi ddcdng suat hieu qua cua dgng co xac dinh theo do cao, [3]:
A'e.ll= A'cO
^ P^-0.11
(3')Cdng suat mdt ddng co xac dinh thdng qua cdng suat tuong duang: N^f. = ^,,^ .A^td- Trong tinh toan nay cdthe chgn ?7^<y= 0,8. Cdng suat tuang duong cua dgng ca pitton bang cong suat dgng ca:
Md = A'cH • Cdng suat hieu qua ciia dgng ca bien ddi theo (3') Vdi: A'e.n ; A'eo ; ^n. Po', TH; TQ- cdng suat, ap suat va nhiet dg d do cao H va do cao H=0.
Bdi vay, [3]:
Theo [4]:
A'lJ = A'e.H = A^eO
A^dc = ricu -A^td = Ko
Lil
Po VH
Tu do:
He,' (4)
Vdi cac sd lieu: « = 3; ^eo = 580O0W; ?7,,/ = 0,8; To = 288,15K; po = 101325 Pa
Sir dung cdng thuc (4) ta tinh loan cdng suat cac dgng co KKC cho cac do cao khac nhau:
A' ^,^^0= 1,392.10-W, vdi H=0, To - 288,I5K; p,, = 101325 Pa.
^Y.'^c.Aoo" 1,311.10^ W. vdiH-400m, r,oo = 284,90K; pjoo = 95461 Pa.
^Y^^c.mo^ 1,233.10' W, vdi H=1000, r,ooo = 281,65K; p.ooo = 89876 Pa,(xem bang 1).
AYas, (N 1 980 3920 6860
Bdng I • Gid tri che do bay khdo sdt cua khinh khi cdu H=Om
Vm,n(m/S)
0.1 2.5 5.2 7.0
Vn,ax(m/S)
26.4 26.42 26.45 26.5
H=4
V,n,n(m/S)
0.2 3.0 5.8 8.0
00m
Vniax ( m / s )
24.2 24.5 24.6 24.65
H= 1000m
Vn„n ( n i / s )
0.3 4.0 6.3 8.7
V^ax (m/s) 24.1 24.3 24.62 24.62
b. Xdc dinh ddc trung lay do cao dn lap thdng qua tinh tdc do bay len thdng dirng Vy.
Tir phuang trinh chuyen ddng dn lap ciia may bay khi lay dd cao dH tren doan bay dL, [2]:
r
(5)
mg X..
Vy Vy
cosO --y.- + mg sin 6
= ^sin dH
dt ' dL
0;
- y..<rx
= P;
COS 0----0;
V ^v dl
Neu<?< 10", cos6' « 1. Thi
^ ^ 2(mgcose-Y,^,cos9) ^ 12AY^ ^ ^ pCv.s
P - X
v., = VsinG = V-^i^ ^ c : > V.
pCv„s AN ,SD m i l - Y„ tnig)sa - Y, AN,,,
V = ~ ' AY,
(6)
(7)
/ W j p - cdng suit su dung, Theo (7). nlu cho trude K ^_| = 3920A', T,^,, = 6860/V va bing cac dudng cong cong suat can va cdng sual cd da xay dyng la cd the ,\ac djnh A A ^ p . Sau khi xac dinh dugc tdc do bay len thang diing cd the lim thdi gian lay do cao de KKC dat do cao cho truoc:
^/ _ ^" trong dd: A/ - thdi szian liy do cao MI. l] ,^ - tdc dd len tbanu trung binh
3. Ket qua
De xac dinb cdng sual cd va cdng sual can, khi cho truoc cac gia irj lyc nang khi tTnh AY^^^^= IN; AK,,, = 980N; A};„, - 3920N; AK,,, = 8680N ta thu dugc he cac dudng cong trong dd tbi dudi day (binh 4, 5): Tren bang 1 cdn the bicn cac che do bay khao sat cua KKC.
Sau khoang 20 pbiit KKC cd the bay dat trin bay thyc te kbi dong co lam viec o che do Idn nhat,
Trin bay ly thuylt cd the dat 7000m khi Vy = 0,5 m, Muc gia tang luc khi tTnh cang Idn thi Iran bay ly thuyet cung nhu thyc lc cang giam
444 Ddng lire hoe bay ciia khinh khi cdu dang dia Elipsoid Cyc tuycn lay do cao la binh 5 va dd tbi quan he toe do bay len thang dung Idn nhit theo do cao va tdc do bay KKC the hien tren hinh 6.
Theo cac gia irj thu nhan dugc ta cd the xay dyng bieu dd lay do cao (binh 7). Bieu dd lay do cao chi ra rang:
- Tdc do len ihang ciia KKC trong ciing mgt gdc tan giam theo do cao. Va trong ciing mgi do cao va loc do bay: muc gia tang lyc kbi iTnb AY^^^. cang Idn thi tdc do len thang cang giam,
- Sau khoang 20 pbiit KKC cd the bay dat Iran bay thyc le khi dgng ca lam viec d che do Idn nhat.
- Tran bay ly thuyet cd the dat 7000ni kbi Ky = 0,5 m. Muc gia tang lyc khi tTnh cang Idn thi Iran bay ly thuyet cung nhu thyc te cang giam.
15
10
N,i, W 10"
H = 0 m H = 400 m
4
ir= mnn m
AK., =6860 N
A / ^ , = 3 9 2 0 N
\
Ay^, = 9 S 0 N \
Vmax
15 20 25 30
Hinh 4: Quan he cdng sudt cd. cdng sudt cdn theo tdc do bay vd mirc gia tdng luc khi tTnh khdc nhau
20 Vy, m/s
15
10 H - 1
Vx, m/s 5 10 15 20 25
Hinh 5: Cue luyen lay do cao cua KKC
sooo 7000
60CO
5000
4000
30O0
2(300
10O0
• . • -
H<M)
-tlt^ tleiyrt
H ,
\ • i V asi = 3920 N
\
\
•-^''asi = 6860 N "•. \
0
Vy^O.SM V, [m/s]
3 n5 TT
Hinh 6: Dd thi tdc do bay len thdng dirng l&n nhdt theo do cao vd tdc do bay KKC 4. Ket luan:
Cac dudng cong cdng suat cd, cdng suat can cho phep xac djnh cac dSc tinh bay cua KKC. Tir dd thi thu nhan due cd the cd mgt sd ket luan sau:
- Tdc do bay quan he chat che vdi cdng suat can: nd cang Idn - tdc do bay cang Idn.
- Tdc do bay nhd nhit Vm,n=0 dat dugc khi AT^,, =0. Luc nay KKC chi sir dung luc nang khi tTnh va hau nhu treo la lirng trong khdng trung, phii hgp [1].
446 Ddng luc hoc bay cua khinh khi cdu dang dia Elipsoid
- Tdc do bay Idn nhit Vn„n=0 dat dugc la 24,5 m/s khi A'„ = N^ , = I3.I0''W. Tdc do Idn nhat hau nhu khong bien doi dgc lap vdi sy bien doi lyc khi tTnh hoac sy bien ddi do cao H = 0-IOOOin
- Gia tri lyc khi tTnh cang Idn thi cong suat can de giu- KKC trong khdng gian cang nho. Tir dd tdc do tdi thieu cang giam.
Bai loan quy dao bay dugc giai quyet tren co so thyc nghiem thdi mo hinh khinh khi cau cd dieu khien dang dTa elip tao dang (Elipsoid), dugc thiet ke tren ca so md hinh toan hge cua GS H.A. Krasanisa. KKC thyc hien lay do cao va bay bang on lap. Cac kit qua thu nhan dugc phu hgp quy luat cho phep xac dinb cac dac tinh bay d cac chl do bay khac. Va Iren ca dd cd the thiet ke va bay thu KKC.
Cdng trinh dugc sy bd trg cua de tai nghien cuu ca ban, chuang trinh cdng nghe vii tru 2008.
4Yapx= 3920(H) 4Yapr=6860(H)=mg;
t(cex) 500 1000 1500 2000
Hinh 7: Bieu dd lay dd cao eiia KKC Tai lieu tham khao
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