NGHIEN CUfU-TRAODdl
NGHIEN CLFU ANH HU'6'NG CClA MOT S 6 YEU T 6 THUAT PHONG NGOAI DEN CHUYiN DONG
CUA DAN B A N DU'6'1 N U ' O C
EFFECT OF SOME EXTERNAL BALLISTIC FACTORS TO THE MOVEMENT OF UNDERWATER BULLET
ThS. Nguyen Van Himg Khoa Vu khi, Hpc vien Ky thuat Quan su
Bai bao trinh bay kit qud nghien cuu dnh huang ciia do sau nuac khi ban (do sau phat ban), sa toe dan den chuyen dong cua dan ban dual nuac bdng thuat todn phan tu hihi han va phan mem Ansys fluent. Kit qud nghien ciru co the dung tham khdo khi tinh todn, thiet ki sung vd dan ban duoi nuac.
Tu- khoa: Ban ban dual nuac; Chuyin dong; Do sau, Van toe dau dan.
ABSTRACT
The paper presents research results the effects of the depth shoot, velocity of a projectile to movement of underwater bullet by finite element algorithm and Ansys fluent software. The research results can be used to design underwater guns and bullets.
Key^vords: Underwater bullet, move, depth, the velocity of a projectile.
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NGHIEN CUfU-TRAOD6l
1. DAT VAN DE
Vii khi nhe trang bi cho cac luc luong dac nhiem, biet kich, nguoi nhai de tac chien duoi nuoc dang dupe quan dpi cac nuac quan tam.
Tren the giai, siing ban duoi nuac da dupe che tao va phat trien gan 40 nam voi cac phien ban khac nhau tir siing ngan SPP-1 (1970) cua Nga, Pll cua Due tiep den cac loai siing tieu Hen APS (1975), sung ti6u lien hai tac dung ASM-DT (2001). Trong khi do, quan dpi ta van chua dupe trang bi cac loai vii khi nay. Vi vay, nghien cuu, thiet kS, che tao siing va dan ban duoi nuac dang la muc tieu cap bach. Khi tinh toan, thiet ke dan ban duoi nuoc thi viec nghien cuu cac yen to anh huong toi chuyen dpng ciia dan la van de thiet yeu.
pha long (nuac), pha khi (hoi nuac trong khoang khong) va h6n hop cua chiing. XuSt phat ttr phuong trinh lien tuc ddi voi thuy dpng luc hpc (phuong trinh Navier - Stockes) [2] ta co:
Hinh 1: Khoang khong bao quanh dan Khi dan chuyen dpng trong nuoc 6 toe dp cao (>80m/s) se hinh thanh mot khoang khong bao quanh dan (hinh 1), khoang khong nay tao ra mot he thuy dpng luc phii'c tap [1]. Cac yeu to anh huong den chuyen dpng cua dan gom co: Hinh dang va kich thuoc ciia dan, m6i truong nuac ma dan chuyen dpng (nhiet dp, mat dp nuoc, dieu kien dong chay, dp sau phat ban...). Dua tren thuat toan phan tir hihi ban va phan mem Ansys, bai bao di sau phan tich anh huong cua dp sau phat ban, so toe dan toi he so ma sat, he s6 khoang kh6ng, su thay doi van toe va tam xa dan.
2. MO HINH BAI TOAN VA PHl/ONG PHAP GIAI
2.1. Xay dimg phirong trinh
Doi voi pha long (nuac):
D6i voi hoi nuoc:
f ( a p J + V - ( a A V ) = R
ot
Doi vai hon hpp hoi - nuoc:
^ ( p ) + V ( p V ) = 0
(1)
(2)
dt (3) Trong do:
R: Toe dp chuyen pha: R = R^ - R^;
R^: T6c dp sinh hoi;
R^: Toe dp hoi ngung tu;
a: The tich hoi nuoc trong hdn hpp: a = f—\
p: Matdph6nhpphai-nuac:/3 = ap^+(l-a)p,; Ph
p,: Mat dp nuoc;
p^: Mat dp hoi nuoc;
V: Van toe.
Kat hpp phuong trinh (1), (2), (3) ta dupe:
(4) ( P ) = -(/?,-A)—(«)
dt ot
R^ va R^ duac xac dinh nhu sau:
>Pi,thi:R^ 5 Trong do:
Ninp > p,thl:R^ = C^^p,p,^^^ • / ( 6 )
Khi dan chuyen dpng duoi nuac se hinh thanh mot he th6ng thiiy khi dpng phiic tap voi hai nuac;
V^^: Toe dp dac trung, no dac trung cho anh huong ciia m6i quan he van t6c giiia ch4t long va
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C,, C^: He so thuc nghiem co gia tri tu0,02 + 0,01.
o: He s6 khoang khong duoc xac dinh: c = pV
2.2. Thdng so dau vao va phircmg phap giai Mo hinh dau dan sic dung co chieu dai 115nim, CO dan 5.7mm va miii dan hu3h non cut CO duong kinh 2nim. Sir dung thuat toan phkn tii hiiu han va phan mem Ansys fluent dh giai.
Ban dau dan ra khoi nong daiiL- o toe dp Ion, khoang khong bao quanh dan dupe lVi:ih thanh va dan chi tiep xiic vai nuac 6 phan miii. Khi van t6c dan giam xuong, he so khoang kh6ng tang dan len, khoang khong phia sau dan chuyen dAn tir hinh tru sang hinh non (hinh 4), dan bat dau mat on dinh. Nhu vay, khi he s6 khoang khong cang Ion (do giam van toe hoac tang chieu sau phat ban) kha nang on dinh cua dan se kem.
Hinh 3: Anh huong do sduphdt ban toi he so khoang khong I) Do sau 40m; 2) Do sau 20m;
3) Do sau JOm; 4) Do sau 5m.
:^= 0.005 0 = 0 . 0 0 9 c = 0.015 (7=0.026 o= 0.039 (7=0.050 (7=0.084
Hmh 2: Vien dgn vd kich thuoc hinh hoc mo hinh dau dan
3. KET QUA VA THAO LUAN
3.1. Anh hirdng dp sau phat ban toi he so khoang khong va sir on dinh cua dan
Sir thay doi ciia he so khoang khong o vao chiSu sau phat ban theo thai gian duoc chi ra a hinh 3. Theo do, a cimg mot thoi gian chuyen dpng, khi tang dp sau phat ban thi he s6 khoang khong giam dkn va a cimg mot dp sau a ciing giam dan theo thai gian.
Hinh 4: Hinh dgng khoang khong sau dlt dan theo he so khodng khong
Hinh 5: Khodng khong bao quanh dgn khi a = 0.039 (a)vd a = 0.050(b)
3.2. Anh hirong cua he so khoang khdng toi he so lu-c can
Khi dan chuyen dpng on dinh duai nuoc, dan chiu tac dung ciia luc c a n F 6 phan miii gom hai thanh phan luc can chinh dien Fp va luc nang F^ . Dac trung cho hai luc nay la cac he so luc can chinh dien va he so luc nang [3]:
_\ Fp \ Fy I F
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Trong do: dan) ta co:
Cp: He so luc can chinh dien;
C^ : He s6 luc nang;
C: He so luc can tong hpp;
Fp: Luc can chinh dien;
Ff: Luc nang;
F: Lye can tong hpp;
A: Dien tich thiet dien dau miii dan.
Tich phan ta dupe:
ImV,
(10)
(11)
trinh:
Im + pACtV^
Tam xa S cua dan duac tinh theo phuong
M6i quan he giira he s6 khoang khong va he so luc can nhu hinh 6. Khi he s6 khoang kh6ng tang len thi he so can tang lam tang luc can tac dung vao dan. Tuy nhien, cac he so luc can tang khong deu va he so luc nang luon be hon he s6 luc can chinh dien.
ds_
dt' (12)
Cac dieu kien dau t - 0, s = 0 ta c6:
2m , 2m+nACtV.
S = In pAC 2m Ta dugc:
2m 2m + pACtV„
~pAC 2m (13)
(14) Ket qua vai cac dp sau phat ban khac nhau nhu hinh 7.
Hinh 6: Moi quan he giita he so luc can vd he s6 khodng khong
3.3. Van toe va t^m xa ciia dan
Phuong trinh chuy8n dpng ciia dan co dang:
0.00 0,02 0.04 0.06 0.08
Ket hpp voi (7) ta dupe:
dV 1 pV^AC
Cac dieu kien d4u t ^ 0, V ^ V (so t6c
Hinh 7: Van toe vd tam xa cua dgn theo do sduphdt ban 1) Tam xa khi ban d do sdu 5m; 2) Tdmxakhibdnddo sdu !0m; 3) Tdm xa khi hdn d do sou 20m; 4) Tdm xa khi ban d do sdu 40m;
a) Van toe khi ban d do sdu 5m; b) Van tdc khi bdn d do sdu 1 Om; c) Van toe khi bdn a do sdu 20m; d) Van tdc
khi bdn d dg sdu 40m.
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NGHIEN CUfU-TRAO 061
4. KET LUAN
Tir ket qua tinh toan ta thay r4ng: DO sau phat bin va so t6c dan co anh hucmg true tiep toi he s6 khoang khong (o), thong qua do anh huong toi luc can va hinh dang khoang khong hinh thanh quanh dan, tiic la anh huong toi 6n dinh va thm xa cua dan. Khi he s6 khoang khong cang lan, thm xa cua dan se giam, do do trong tinh toan thik kk dan bdn duoi nuoc phai lua chpn cac thong so hop ly de lam giam o. Ket qua nghien cihi ciia bai toan co th6 dung tham khao trong qua trinh thiSt ke dan ban duoi nuac. •
Ngay nhan bai: 10/5/2014 Ngay phan bien: 19/5/2014
Tai lifu tham Idiao:
[1]. Daijin Li, Yuwen Zhang, Kai Luo, Janjun Dang, Motion Control of Underwater Supercavitating Projectiles in Vertical Plane, Modem Applied Science, Vol.3, No.2, February 2009.
[2], Milada Kozubkova, Jana Rautova, Marian Bojkoc, Mathematical Model of Cavitation and Mod- elling of Fluid Flow in Cone, Xlllth International Scientific and Engineering Conference "HERVI- CON-2011".
[3]. Richard Rand, Rudra Pratap, Deepak Ramani, Jeffery Cipolla, Ivan Kirschner, Impact dynamic of a supercavitating underwater projectile,\991 ASME Design Engineering Technical Conferences.
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