1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293 | # Applied Python PRISM
# (PRISM) PaRametrIc System Model
#
# Written by Charlie Taylor <cet@appliedpython.com>
# Feb 15, 2007
#
# Adding Jim Ponzo scaling equations 3/26/2008
from math import *
from prism.MassItem import MassItem
from prism.props import Materials
from prism.Summary import Summary
from math import *
from prism.pov import POV_Items, POV_Basics
# Model of Piston tank. very thin metal shell overwrapped with composite
# positive expulsion with a piston
#C INPUT
#C vfree-total volume Usabel Volume (ullage plus propellant)
# (does NOT include Residual Propellant)
#C ptank-pressure in tank
#C SF-safety factor
#C CXW-tank weight multiplier (welds, bosses, etc.)
#C INPEX-input expulsion efficiency flag(0=calculate eff,1=input)
#C EXPEFI-input expulsion efficiency
exp_dict = {0:'calculate expulsion eff',1:'input expulsion eff'}
class Tank_Piston( MassItem ):
def __init__(self, name="tank", mass_lbm=0.0,
inputLoverD=1, metalName="Ti", overwrapName="grEpox",
vfree=4.0,ptank=1400.0,
sf=1.5,cxw=1.0,Number=1,
inpex=0,expefi=0.99, dPpiston=10.0, LoDpiston=0.45,
LoverD=5.0,Dinside=1.0, thkMetal_minG=0.010, thkMetal=None,
thkOvInput=None, thkMetalInp=None):
MassItem.__init__(self, name, type="inert", mass_lbm=mass_lbm)
self.inputLoverD = inputLoverD
self.metalName = metalName
self.thkMetal_minG = thkMetal_minG
# maintain backward compatibility with thkMetal input
if thkMetal:
self.thkMetal_minG = thkMetal
self.overwrapName = overwrapName
self.rhoMetal, self.syMetal, self.eMetal, self.tmingMetal = Materials.getMatlProps(metalName)
self.tmingMetal = thkMetal_minG
self.thkOvInput = thkOvInput
self.thkMetalInp = thkMetalInp
self.rhoOv, self.syOv, self.eOv, self.tmingOv = Materials.getMatlProps(overwrapName)
self.Number = Number # each tank has vfree
self.vfree = vfree
self.LoverD = LoverD
self.LoDpiston = LoDpiston
self.ptank = ptank
self.sf = sf
self.cxw = cxw
self.Dinside = Dinside
self.inpex = inpex
self.expefi = expefi
self.dPpiston = dPpiston
self.reCalc()
def getPOV_Item(self):
if hasattr( self, 'texture'):
texture = self.texture
else:
texture = POV_Basics.Texture( colorName="Gray50" )
s = POV_Items.Cylinder( texture=texture, bottom=[0,0,0], top=[0,self.Ltotal,0], radius=self.radius )
return s
def reCalc(self):
default_cxw = 1.0
# reference values for piston tank
P1 = 1400.0 # MEOP
r1 = 1.625 / 2.0 # inside radius
a1 = 0.010 # metal thickness
b1 = 0.007 # overwrap thickness
Em = self.eMetal
En = self.eOv
SF1 = 1.5 # 2100/1400 = design burst / design MEOP
t1 = r1 / 4.0 # end cap thickness
# get diameter and wet length figured out
if not self.inputLoverD: # Dinside is input
self.Across = pi*self.Dinside**2/4.0
self.Lwet = self.vfree / self.Across
self.LoverD = self.Lwet / self.Dinside
else: # LoverD is input
self.Dinside = (4. * self.vfree / pi / self.LoverD)**(1./3.)
self.Across = pi*self.Dinside**2/4.0
self.Lwet = self.vfree / self.Across
# get inside radius
self.radius = self.Dinside / 2.0
R = self.radius
r2 = R
# assume dPpiston = const
self.pullag = self.ptank + self.dPpiston
P2 = self.pullag
# figure out lengths of piston and heads
self.Lpiston = self.LoDpiston * self.Dinside
t2_deflect= t1 * (r2/r1)**(3./2.) * sqrt(P2/P1)
t2_stress = t1 * (r2/r1) * sqrt(P2/P1)
self.Lhead = max( t2_stress, t2_deflect )
if self.Lhead < self.tmingMetal:
self.Lhead = self.tmingMetal
self.Ltotal = self.Lwet + self.Lpiston + self.Lhead*2.0
# calc metal thickness
a2 = sqrt((P2/P1)*(r2/r1)**2 * ((r1+a1)**2 - r1**2) + r2**2) - r2
b2 = (r2+a2)**2 / En * ((P2/P1)*(Em*a1/r1**2 + En*b1/(r1+a1)**2) - Em*a2/r2**2)
self.thkMetal = self.sf * a2 / SF1
if self.thkMetal < self.tmingMetal:
self.thkMetal = self.tmingMetal
if self.thkMetalInp:
self.thkMetal = self.thkMetalInp
# calc overwrap thickness
self.thkOv = self.sf * b2 / SF1
if self.thkOv < self.tmingOv:
self.thkOv = self.tmingOv
if self.thkOvInput:
self.thkOv = self.thkOvInput
if self.thkOv <= self.tmingOv:
self.Pburst = self.tmingOv * self.syOv / (R+self.thkMetal)
else:
self.Pburst = self.sf * self.pullag
# weigh metal shell, overwrap, piston, and heads
Vshell = pi * ((R+self.thkMetal)**2-R**2) * self.Ltotal
self.WmetalShell = Vshell * self.rhoMetal
Vovr = pi * ( (R+self.thkMetal+self.thkOv)**2 - (R+self.thkMetal)**2 ) * self.Ltotal
self.Woverwrap = Vovr * self.rhoOv
self.thkPiston = R/20.
if self.thkPiston < self.tmingMetal:
self.thkPiston = self.tmingMetal
# base shell seal inner shell seal cross pieces
SApiston = pi*R**2 + 2.*pi*R*self.Lpiston + 2.*pi*(0.7*R)*(0.35*R) + pi*(R**2 - (.7*R)**2)*2.
self.Wpiston = SApiston * self.rhoMetal * self.thkPiston
self.Whead = self.Lhead * pi * R**2 * 0.8 * self.rhoMetal
# get total mass
self.Wtotal = self.WmetalShell + self.Woverwrap + self.Wpiston + self.Whead*2.0
self.vresid=(1.-self.expefi)*self.vfree
self.vtank = self.vresid + self.vfree
self.mass_lbm = self.Wtotal * self.cxw
# if more than one tank, increase mass to reflect that
self.mass_lbm *= self.Number
try:
self.PVoverW = self.ptank *self.vtank*self.Number/self.mass_lbm
self.PburstVoverW = self.Pburst*self.vtank*self.Number/self.mass_lbm
except:
self.PVoverW = 0.0
self.PburstVoverW = 0.0
self.pov_h = self.Ltotal
self.pov_w = self.Dinside
self.pov_d = self.Dinside
self.OD = self.Dinside + 2.0 *( self.thkOv + self.thkMetal )
self.OR = self.OD / 2.0
self.OH = self.Ltotal
def buildSummary(self):
summ = Summary( summName='Positive Expulsion Piston Tank',
componentName=self.name, mass_lbm=self.mass_lbm, type=self.type)
summ.addAssumption('Piston Tank')
summ.addAssumption('Metallic Material : ' + self.metalName )
summ.addAssumption('Overwrap Material : ' + self.overwrapName )
summ.addAssumption('inputLoverD = ' + str( self.inputLoverD ) )
if self.Number>1:
summ.addAssumption( 'Mass is for %i Tanks total'%self.Number )
# add inputs
summ.addInput('vfree', self.vfree, 'cuin', '%g')
if self.Number>1:
summ.addInput('vfreeTotal', self.vfree*self.Number, 'cuin', '%g')
if self.inputLoverD:
summ.addInput('LoverD', self.LoverD, '', '%g')
else:
summ.addInput( 'Dinside', self.Dinside, 'in', '%.3f' )
summ.addInput('ptank', self.ptank, 'psia', '%g')
summ.addInput('dPpiston', self.dPpiston, 'psig', '%g' )
summ.addInput('sf', self.sf, '', '%g')
summ.addInput('thkMetal_minG', self.thkMetal_minG, 'in', '%.3f')
summ.addInput('cxw', self.cxw, '', '%g')
summ.addInput('inpex', self.inpex, '', '%g')
summ.addInput('expefi', self.expefi, '', '%g')
# add outputs
summ.addOutput( 'radius', self.radius, 'in', '%.3f' )
if self.inputLoverD:
summ.addOutput( 'Dinside', self.Dinside, 'in', '%.3f' )
else:
summ.addOutput('LoverD', self.LoverD, '', '%g')
summ.addOutput( 'OD', self.OD, 'in', '%.3f' )
summ.addOutput( 'thkPiston', self.thkPiston, 'in', '%.3f' )
summ.addOutput( 'thkOv', self.thkOv, 'in', '%.3f' )
summ.addOutput( 'thkMetal', self.thkMetal, 'in', '%.3f' )
summ.addOutput( 'rhoMetal', self.rhoMetal, 'lbm/cuin', '%g' )
summ.addOutput( 'rhoOv', self.rhoOv, 'lbm/cuin', '%g' )
summ.addOutput( 'designStress', self.syOv, 'psi', '%.0f' )
summ.addOutput( 'Lpiston', self.Lpiston, 'in', '%.3f' )
summ.addOutput( 'Lhead', self.Lhead, 'in', '%.3f' )
summ.addOutput( 'Lwet', self.Lwet, 'in', '%.3f' )
summ.addOutput( 'Ltotal', self.Ltotal, 'in', '%.3f' )
summ.addOutput( 'vresid', self.vresid, 'cuin', '%g' )
summ.addOutput( 'vtank', self.vtank, 'cuin', '%g' )
summ.addOutput( 'WmetalShell', self.WmetalShell, 'lbm', '%.3f' )
summ.addOutput( 'Woverwrap', self.Woverwrap, 'lbm', '%.3f' )
summ.addOutput( 'Whead', self.Whead, 'lbm', '%.3f' )
summ.addOutput( 'Wpiston', self.Wpiston, 'lbm', '%.3f' )
summ.addOutput( 'Wtotal', self.Wtotal, 'lbm', '%.3f' )
summ.addOutput( 'pullag', self.pullag, 'psia', '%.0f' )
summ.addOutput( 'Pburst', self.Pburst, 'psia', '%.0f' )
summ.addOutput( 'PVoverW', self.PVoverW, 'lbf-in/lbm', '%.0f' )
summ.addOutput( 'SF*PVoverW', self.sf*self.PVoverW, 'lbf-in/lbm', '%.0f' )
summ.addOutput( 'PburstVoverW', self.PburstVoverW, 'lbf-in/lbm', '%.0f' )
return summ
if __name__ == "__main__": #self test
print "Calculated = ",
testTnk = Tank_Piston(name="Piston tank", mass_lbm=0.0,
inputLoverD=0, metalName="Ti", overwrapName="grEpox",
vfree=4.0*2.25,LoverD=5.0,ptank=1400.0,
sf=1.5,cxw=1.02,
inpex=0,expefi=0.99,
Dinside=2.0*0.85)
print testTnk.getMassStr()
print
print testTnk.getSummary()
if 0:
print "Calculated = ",
testTnk = Tank_Piston(name="Large Piston tank", mass_lbm=0.0,
inputLoverD=1, metalName="Ti", overwrapName="grEpox",
vfree=40.0,LoverD=5.0,ptank=1400.0,
sf=1.5,cxw=1.02, Number=1,
inpex=0,expefi=0.99,
Dinside=1.0 )
print testTnk.getMassStr()
print
print testTnk.getSummary()
|