def test_bearing_link_global_index():
b0 = BearingElement(n=0, n_link=3, kxx=1, cxx=1)
idx = b0.dof_global_index()
assert idx.x_0 == 0
assert idx.y_0 == 1
print(idx)
assert idx.x_3 == 12
assert idx.y_3 == 13
def test_bearing_link_matrices():
b0 = BearingElement(n=0, n_link=3, kxx=1, cxx=1)
# fmt: off
M = np.array([[1, 0, -1, 0], [0, 1, 0, -1], [-1, 0, 1, 0], [0, -1, 0, 1]])
# fmt: on
assert_allclose(b0.K(0), M)
assert_allclose(b0.C(0), M)
def test_bearing_error2():
with pytest.raises(ValueError) as excinfo:
BearingElement(4,
kxx=[7e8, 8e8, 9e8],
cxx=[0, 0, 0, 0],
frequency=[10, 100, 1000, 10000])
assert ("Arguments (coefficients and frequency) "
"must have the same dimension" in str(excinfo.value))
with pytest.raises(ValueError) as excinfo:
BearingElement(4, kxx=[6e8, 7e8, 8e8, 9e8], cxx=[0, 0, 0, 0, 0])
assert ("Arguments (coefficients and frequency) "
"must have the same dimension" in str(excinfo.value))
def test_bearing_len_3():
bearing = BearingElement(
n=0,
kxx=[481, 4810, 18810],
cxx=[3.13, 10.81, 22.99],
kyy=[481, 4810, 18810],
kxy=[194, 2078, 8776],
kyx=[-194, -2078, -8776],
cyy=[3.13, 10.81, 22.99],
cxy=[0.276, 0.69, 1.19],
cyx=[-0.276, -0.69, -1.19],
frequency=[115.19, 345.575, 691.15],
)
assert_allclose(bearing.kxx_interpolated(115.19), 481, rtol=1e5)
def test_bearing_len_2():
bearing = BearingElement(
n=0,
kxx=[481, 4810],
cxx=[3.13, 10.81],
kyy=[481, 4810],
kxy=[194, 2078],
kyx=[-194, -2078],
cyy=[3.13, 10.81],
cxy=[0.276, 0.69],
cyx=[-0.276, -0.69],
frequency=[115.19, 345.575],
)
assert_allclose(bearing.kxx_interpolated(115.19), 481, rtol=1e5)
def test_save_load(bearing0, bearing_constant, bearing_6dof):
file = Path(tempdir) / "bearing0.toml"
bearing0.save(file)
bearing0_loaded = BearingElement.load(file)
assert bearing0 == bearing0_loaded
file = Path(tempdir) / "bearing_constant.toml"
bearing_constant.save(file)
bearing_constant_loaded = BearingElement.load(file)
assert bearing_constant == bearing_constant_loaded
file = Path(tempdir) / "bearing_6dof.toml"
bearing_6dof.save(file)
bearing_6dof_loaded = BearingElement6DoF.load(file)
assert bearing_6dof == bearing_6dof_loaded
def test_from_table():
bearing_file = (os.path.dirname(os.path.realpath(__file__)) +
"/data/bearing_seal_si.xls")
bearing = BearingElement.from_table(0, bearing_file)
assert bearing.n == 0
assert_allclose(bearing.frequency[2], 523.5987755985)
assert_allclose(bearing.kxx.coefficient[2], 53565700)
# bearing with us units
bearing_file = (os.path.dirname(os.path.realpath(__file__)) +
"/data/bearing_seal_us.xls")
bearing = BearingElement.from_table(0, bearing_file)
assert bearing.n == 0
assert_allclose(bearing.frequency[2], 523.5987755985)
assert_allclose(bearing.kxx.coefficient[2], 53565700)
def bearing1():
# using lists
Kxx_bearing = [
8.5e07,
1.1e08,
1.3e08,
1.6e08,
1.8e08,
2.0e08,
2.3e08,
2.5e08,
2.6e08,
]
Kyy_bearing = np.array([
9.2e07, 1.1e08, 1.4e08, 1.6e08, 1.9e08, 2.1e08, 2.3e08, 2.5e08, 2.6e08
])
Cxx_bearing = np.array([
226837, 211247, 197996, 185523, 174610, 163697, 153563, 144209, 137973
])
Cyy_bearing = np.array([
235837, 211247, 197996, 185523, 174610, 163697, 153563, 144209, 137973
])
wb = [314.2, 418.9, 523.6, 628.3, 733.0, 837.8, 942.5, 1047.2, 1151.9]
bearing1 = BearingElement(
4,
kxx=Kxx_bearing,
kyy=Kyy_bearing,
cxx=Cxx_bearing,
cyy=Cyy_bearing,
frequency=wb,
)
return bearing1
def test_bearing_error_speed_not_given():
speed = np.linspace(0, 10000, 5)
kx = 1e8 * speed
cx = 1e8 * speed
with pytest.raises(Exception) as excinfo:
BearingElement(-1, kxx=kx, cxx=cx)
assert ("Arguments (coefficients and frequency)"
" must have the same dimension" in str(excinfo.value))
def test_st_point_mass_elements_odd_length():
tim0 = ShaftElement(L=0.25, idl=0, odl=0.05, material=steel)
tim1 = ShaftElement(L=0.25, idl=0, odl=0.05, material=steel)
shaft_elm = [tim0, tim1]
disk0 = DiskElement(n=1, m=20, Id=1, Ip=1)
brg0 = BearingElement(n=0, kxx=1e6, cxx=1e3, n_link=3)
brg1 = BearingElement(n=2, kxx=1e6, cxx=1e3, n_link=4)
sup0 = BearingElement(n=3, kxx=1e6, cxx=1e3)
sup1 = BearingElement(n=4, kxx=1e6, cxx=1e3)
pm0 = ST_PointMass(n=3, m=[1, 2], is_random=["m"])
pm1 = ST_PointMass(n=4, m=[1, 2, 3], is_random=["m"])
with pytest.raises(ValueError) as ex:
ST_Rotor(shaft_elm, [disk0], [brg0, brg1, sup0, sup1], [pm0, pm1])
assert "not all random point mass lists have same length." in str(ex.value)
def test_save_load(bearing0, bearing_constant, bearing_6dof, magnetic_bearing):
file = Path(tempdir) / "bearing0.toml"
bearing0.save(file)
bearing0_loaded = BearingElement.load(file)
assert bearing0 == bearing0_loaded
file = Path(tempdir) / "bearing_constant.toml"
bearing_constant.save(file)
bearing_constant_loaded = BearingElement.load(file)
assert bearing_constant == bearing_constant_loaded
file = Path(tempdir) / "bearing_6dof.toml"
bearing_6dof.save(file)
bearing_6dof_loaded = BearingElement6DoF.load(file)
assert bearing_6dof == bearing_6dof_loaded
file = Path(tempdir) / "magnetic_bearing.toml"
magnetic_bearing.save(file)
magnetic_bearing_loaded = MagneticBearingElement.load(file)
assert magnetic_bearing == magnetic_bearing_loaded
def report2():
# rotor type: single double overhung
i_d = 0.0
o_d = 0.05
n = 50
L = [0.03 for _ in range(n)]
shaft_elem = [
ShaftElement(l,
i_d,
o_d,
material=steel,
shear_effects=True,
rotary_inertia=True,
gyroscopic=True) for l in L
]
disk0 = DiskElement.from_geometry(n=0,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.28)
disk1 = DiskElement.from_geometry(n=50,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.35)
stfx = 1e6
stfy = 0.8e6
bearing0 = BearingElement(15, kxx=stfx, kyy=stfy, cxx=1000)
bearing1 = BearingElement(35, kxx=stfx, kyy=stfy, cxx=1000)
rotor = Rotor(shaft_elem, [disk0, disk1], [bearing0, bearing1])
minspeed = 3820.0
maxspeed = 9550.0
machine_type = "pump"
units = "rpm"
return Report(rotor, minspeed, maxspeed, machine_type, units)
def report0():
# rotor type: between bearings
i_d = 0.0
o_d = 0.05
n = 50
L = [0.03 for _ in range(n)]
shaft_elem = [
ShaftElement(l,
i_d,
o_d,
material=steel,
shear_effects=True,
rotary_inertia=True,
gyroscopic=True) for l in L
]
disk0 = DiskElement.from_geometry(n=15,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.28)
disk1 = DiskElement.from_geometry(n=35,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.35)
stfx = 1e6
stfy = 0.8e6
bearing0 = BearingElement(0, kxx=stfx, kyy=stfy, cxx=1000)
bearing1 = BearingElement(50, kxx=stfx, kyy=stfy, cxx=1000)
rotor = Rotor(shaft_elem, [disk0, disk1], [bearing0, bearing1])
minspeed = 400.0
maxspeed = 1000.0
machine_type = "compressor"
units = "rad/s"
return Report(rotor, minspeed, maxspeed, machine_type, units)
def random_var(self, is_random, *args):
"""Generate a list of objects as random attributes.
This function creates a list of objects with random values for selected
attributes from ross.BearingElement.
Parameters
----------
is_random : list
List of the object attributes to become stochastic.
*args : dict
Dictionary instanciating the ross.BearingElement class.
The attributes that are supposed to be stochastic should be
set as lists of random variables.
Returns
-------
f_list : generator
Generator of random objects.
"""
args_dict = args[0]
new_args = []
try:
for i in range(len(args_dict[is_random[0]][0])):
arg = []
for key, value in args_dict.items():
if key in is_random:
arg.append([value[j][i] for j in range(len(value))])
else:
arg.append(value)
new_args.append(arg)
except TypeError:
for i in range(len(args_dict[is_random[0]])):
arg = []
for key, value in args_dict.items():
if key in is_random:
arg.append(value[i])
else:
arg.append(value)
new_args.append(arg)
f_list = (BearingElement(*arg) for arg in new_args)
return f_list
def bearing0():
Kxx_bearing = np.array([
8.5e07, 1.1e08, 1.3e08, 1.6e08, 1.8e08, 2.0e08, 2.3e08, 2.5e08, 2.6e08
])
Kyy_bearing = np.array([
9.2e07, 1.1e08, 1.4e08, 1.6e08, 1.9e08, 2.1e08, 2.3e08, 2.5e08, 2.6e08
])
Cxx_bearing = np.array([
226837, 211247, 197996, 185523, 174610, 163697, 153563, 144209, 137973
])
Cyy_bearing = np.array([
235837, 211247, 197996, 185523, 174610, 163697, 153563, 144209, 137973
])
wb = np.array(
[314.2, 418.9, 523.6, 628.3, 733.0, 837.8, 942.5, 1047.2, 1151.9])
bearing0 = BearingElement(4,
kxx=Kxx_bearing,
kyy=Kyy_bearing,
cxx=Cxx_bearing,
cyy=Cyy_bearing,
w=wb)
return bearing0
def stability_level_1(self, D, H, HP, oper_speed, RHO_ratio, RHOs, RHOd, unit="m"):
"""Stability analysis level 1.
This analysis consider a anticipated cross coupling QA based on
conditions at the normal operating point and the cross-coupling
required to produce a zero log decrement, Q0.
Components such as seals and impellers are not considered in this
analysis.
Parameters
----------
D: list
Impeller diameter, m (in.),
Blade pitch diameter, m (in.),
H: list
Minimum diffuser width per impeller, m (in.),
Effective blade height, m (in.),
HP: list
Rated power per stage/impeller, W (HP),
oper_speed: float
Operating speed, rpm,
RHO_ratio: list
Density ratio between the discharge gas density and the suction
gas density per impeller (RHO_discharge / RHO_suction),
kg/m3 (lbm/in.3),
RHOs: float
Suction gas density in the first stage, kg/m3 (lbm/in.3).
RHOd: float
Discharge gas density in the last stage, kg/m3 (lbm/in.3),
unit: str, optional
Adopted unit system. Options are "m" (meter) and "in" (inch)
Default is "m"
Attributes
----------
condition: str
not required: Stability Level 1 satisfies the analysis;
required: Stability Level 2 is required.
Return
------
fig1: bokeh.figure
Applied Cross-Coupled Stiffness vs. Log Decrement plot;
fig2: bokeh.figure
CSR vs. Mean Gas Density plot.
Example
-------
>>> rotor = rotor_example()
>>> report = Report(rotor=rotor,
... minspeed=400,
... maxspeed=1000,
... speed_units="rad/s")
>>> stability = report.stability_level_1(D=[0.35, 0.35],
... H=[0.08, 0.08],
... HP=[10000, 10000],
... RHO_ratio=[1.11, 1.14],
... RHOd=30.45,
... RHOs=37.65,
... oper_speed=1000.0)
>>> report.Qa
23022.32142857143
"""
steps = 11
if unit == "m":
C = 9.55
elif unit == "in":
C = 63.0
else:
raise TypeError("choose between meters (m) or inches (in)")
if len(D) != len(H):
raise Exception("length of D must be the same of H")
Qa = 0.0
cross_coupled_array = np.array([])
# Qa - Anticipated cross-coupling for compressors - API 684 - SP6.8.5.6
if self.machine_type == "compressor":
Bc = 3.0
Dc, Hc = D, H
for i, disk in enumerate(self.rotor.disk_elements):
if disk.n in self.disk_nodes:
qi = HP[i] * Bc * C * RHO_ratio[i] / (Dc[i] * Hc[i] * oper_speed)
Qi = np.linspace(0, 10 * qi, steps)
cross_coupled_array = np.append(cross_coupled_array, Qi)
Qa += qi
# Qa - Anticipated cross-coupling for turbines - API 684 - SP6.8.5.6
if self.machine_type == "turbine" or self.machine_type == "axial_flow":
Bt = 1.5
Dt, Ht = D, H
for i, disk in enumerate(self.rotor.disk_elements):
if disk.n in self.disk_nodes:
qi = (HP[i] * Bt * C) / (Dt[i] * Ht[i] * oper_speed)
Qi = np.linspace(0, 10 * qi, steps)
cross_coupled_array = np.append(cross_coupled_array, Qi)
Qa += qi
# Defining cross-coupling range to 10*Qa - API 684 - SP6.8.5.8
Qi = np.linspace(0, 10 * Qa, steps)
cross_coupled_array = np.append(cross_coupled_array, Qi)
cross_coupled_array = cross_coupled_array.reshape(
[len(self.disk_nodes) + 1, steps]
).T
log_dec = np.zeros(len(cross_coupled_array))
# remove disks and seals from the rotor model
bearing_list = [
copy(b)
for b in self.rotor.bearing_seal_elements
if b.__class__.__name__ != "SealElement"
]
# Applying cross-coupling on rotor mid-span
if self.rotor_type == "between_bearings":
for i, Q in enumerate(cross_coupled_array[:, -1]):
bearings = [copy(b) for b in bearing_list]
# cross-coupling introduced at the rotor mid-span
n = np.round(np.mean(self.rotor.nodes))
cross_coupling = BearingElement(n=int(n), kxx=0, cxx=0, kxy=Q, kyx=-Q)
bearings.append(cross_coupling)
aux_rotor = Rotor(
shaft_elements=self.rotor.shaft_elements,
disk_elements=[],
bearing_seal_elements=bearings,
rated_w=self.rotor.rated_w,
)
modal = aux_rotor.run_modal(speed=oper_speed * np.pi / 30)
non_backward = modal.whirl_direction() != "Backward"
log_dec[i] = modal.log_dec[non_backward][0]
# Applying cross-coupling for each disk - API 684 - SP6.8.5.9
else:
for i, Q in enumerate(cross_coupled_array[:, :-1]):
bearings = [copy(b) for b in bearing_list]
# cross-coupling introduced at overhung disks
for n, q in zip(self.disk_nodes, Q):
cross_coupling = BearingElement(
n=n, kxx=0, cxx=0, kxy=q, kyx=-q
)
bearings.append(cross_coupling)
aux_rotor = Rotor(
shaft_elements=self.rotor.shaft_elements,
disk_elements=[],
bearing_seal_elements=bearings,
rated_w=self.rotor.rated_w,
)
modal = aux_rotor.run_modal(speed=oper_speed * np.pi / 30)
non_backward = modal.whirl_direction() != "Backward"
log_dec[i] = modal.log_dec[non_backward][0]
# verifies if log dec is greater than zero to begin extrapolation
cross_coupled_Qa = cross_coupled_array[:, -1]
if log_dec[-1] >= 0:
g = interp1d(
cross_coupled_Qa, log_dec, fill_value="extrapolate", kind="linear"
)
stiff = cross_coupled_Qa[-1] * (1 + 1 / (len(cross_coupled_Qa)))
while g(stiff) > 0:
log_dec = np.append(log_dec, g(stiff))
cross_coupled_Qa = np.append(cross_coupled_Qa, stiff)
stiff += cross_coupled_Qa[-1] / (len(cross_coupled_Qa))
Q0 = cross_coupled_Qa[-1]
else:
idx = min(range(len(log_dec)), key=lambda i: abs(log_dec[i]))
Q0 = cross_coupled_Qa[idx]
# Find value for log_dec corresponding to Qa
log_dec_a = log_dec[np.where(cross_coupled_Qa == Qa)][0]
# CSR - Critical Speed Ratio
crit_speed = self.rotor.run_modal(speed=self.maxspeed).wn[0]
CSR = self.maxspeed / crit_speed
# RHO_mean - Average gas density
RHO_mean = (RHOd + RHOs) / 2
RHO = np.linspace(0, RHO_mean * 5, 501)
# CSR_boundary - function to define the CSR boundaries
CSR_boundary = np.piecewise(
RHO,
[RHO <= 16.53, RHO > 16.53, RHO == 60, RHO > 60],
[2.5, lambda RHO: (-0.0115 * RHO + 2.69), 2.0, 0.0],
)
# Plotting area
fig1 = figure(
tools="pan, box_zoom, wheel_zoom, reset, save",
title="Applied Cross-Coupled Stiffness vs. Log Decrement - (API 684 - SP 6.8.5.10)",
width=640,
height=480,
x_axis_label="Applied Cross-Coupled Stiffness, Q (N/m)",
y_axis_label="Log Dec",
x_range=(0, max(cross_coupled_Qa)),
y_range=DataRange1d(start=0),
)
fig1.title.text_font_size = "14pt"
fig1.xaxis.axis_label_text_font_size = "20pt"
fig1.yaxis.axis_label_text_font_size = "20pt"
fig1.axis.major_label_text_font_size = "16pt"
fig1.line(
cross_coupled_Qa, log_dec, line_width=3, line_color=bokeh_colors[0]
)
fig1.circle(Qa, log_dec_a, size=8, fill_color=bokeh_colors[0])
fig1.add_layout(
Label(
x=Qa,
y=log_dec_a,
text="Qa",
text_font_style="bold",
text_font_size="12pt",
text_baseline="middle",
text_align="left",
y_offset=10
)
)
if unit == "m":
f = 0.062428
x_label1 = "kg/m³"
x_label2 = "lb/ft³"
if unit == "in":
f = 16.0185
x_label1 = "lb/ft³"
x_label2 = "kg/m³"
fig2 = figure(
tools="pan, box_zoom, wheel_zoom, reset, save",
title="CSR vs. Mean Gas Density - (API 684 - SP 6.8.5.10)",
width=640,
height=480,
x_axis_label=x_label1,
y_axis_label="MCSR",
y_range=DataRange1d(start=0),
x_range=DataRange1d(start=0),
)
fig2.title.text_font_size = "14pt"
fig2.xaxis.axis_label_text_font_size = "20pt"
fig2.yaxis.axis_label_text_font_size = "20pt"
fig2.axis.major_label_text_font_size = "16pt"
fig2.extra_x_ranges = {"x_range2": Range1d(f * min(RHO), f * max(RHO))}
fig2.add_layout(
LinearAxis(
x_range_name="x_range2",
axis_label=x_label2,
axis_label_text_font_size="11pt",
),
place="below",
)
fig2.add_layout(
Label(
x=RHO_mean,
y=CSR,
text=self.tag,
text_font_style="bold",
text_font_size="12pt",
text_baseline="middle",
text_align="left",
x_offset=10,
)
)
for txt, x, y in zip(["Region A", "Region B"], [30, 60], [1.20, 2.75]):
fig2.add_layout(
Label(
x=x,
y=y,
text=txt,
text_alpha=0.4,
text_font_style="bold",
text_font_size="12pt",
text_baseline="middle",
text_align="center",
)
)
fig2.line(x=RHO, y=CSR_boundary, line_width=3, line_color=bokeh_colors[0])
fig2.circle(x=RHO_mean, y=CSR, size=8, color=bokeh_colors[0])
# Level 1 screening criteria - API 684 - SP6.8.5.10
idx = min(range(len(RHO)), key=lambda i: abs(RHO[i] - RHO_mean))
if self.machine_type == "compressor":
if Q0 / Qa < 2.0:
condition = "required"
if log_dec_a < 0.1:
condition = "required"
if 2.0 < Q0 / Qa < 10.0 and CSR > CSR_boundary[idx]:
condition = "required"
else:
condition = "not required"
if self.machine_type == "turbine" or self.machine_type == "axial flow":
if log_dec_a < 0.1:
condition = "required"
else:
condition = "not required"
# updating attributes
self.Q0 = Q0
self.Qa = Qa
self.log_dec_a = log_dec_a
self.CSR = CSR
self.Qratio = Q0 / Qa
self.crit_speed = crit_speed
self.MCS = self.maxspeed
self.RHO_gas = RHO_mean
self.condition = condition
return fig1, fig2
def report2():
# rotor type: double overhung
i_d = 0
o_d = 0.05
n = 6
L = [0.25 for _ in range(n)]
shaft_elem = [
ShaftElement(
l,
i_d,
o_d,
material=steel,
shear_effects=True,
rotary_inertia=True,
gyroscopic=True,
) for l in L
]
disk0 = DiskElement.from_geometry(n=0,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.28)
disk1 = DiskElement.from_geometry(n=6,
material=steel,
width=0.07,
i_d=0.05,
o_d=0.28)
stfx = [0.4e7, 0.5e7, 0.6e7, 0.7e7]
stfy = [0.8e7, 0.9e7, 1.0e7, 1.1e7]
freq = [400, 800, 1200, 1600]
bearing0 = BearingElement(2, kxx=stfx, kyy=stfy, cxx=2e3, frequency=freq)
bearing1 = BearingElement(4, kxx=stfx, kyy=stfy, cxx=2e3, frequency=freq)
oper_clerance_brg = [bearing0, bearing1]
rotor = Rotor(shaft_elem, [disk0, disk1], [bearing0, bearing1])
# coefficients for minimum clearance
stfx = [0.7e7, 0.8e7, 0.9e7, 1.0e7]
dampx = [2.0e3, 1.9e3, 1.8e3, 1.7e3]
freq = [400, 800, 1200, 1600]
bearing0 = BearingElement(2, kxx=stfx, cxx=dampx, frequency=freq)
bearing1 = BearingElement(4, kxx=stfx, cxx=dampx, frequency=freq)
min_clearance_brg = [bearing0, bearing1]
# coefficients for maximum clearance
stfx = [0.4e7, 0.5e7, 0.6e7, 0.7e7]
dampx = [2.8e3, 2.7e3, 2.6e3, 2.5e3]
freq = [400, 800, 1200, 1600]
bearing0 = BearingElement(2, kxx=stfx, cxx=dampx, frequency=freq)
bearing1 = BearingElement(4, kxx=stfx, cxx=dampx, frequency=freq)
max_clearance_brg = [bearing0, bearing1]
config = Config()
config.update_config(
rotor_properties={
"rotor_speeds": {
"min_speed": 3820.0,
"max_speed": 9550.0,
"oper_speed": 8000.0,
"trip_speed": 10500.0,
"unit": "rpm",
},
"rotor_id": {
"type": "axial_flow"
},
},
bearings={
"oper_clearance": oper_clerance_brg,
"min_clearance": min_clearance_brg,
"max_clearance": max_clearance_brg,
},
run_campbell={"speed_range": np.linspace(0, 1500, 51)},
run_unbalance_response={
"probes": {
"node": [1, 4],
"orientation": [np.pi / 2, np.pi / 2],
"unit": "rad",
},
"frequency_range": np.linspace(0, 1500, 101),
"plot_deflected_shape": {
"speed": [615]
},
},
plot_ucs={"stiffness_range": (5, 8)},
stability_level1={
"D": [0.35, 0.35],
"H": [0.08, 0.08],
"rated_power": [6000, 8000],
"rho_ratio": [1.11, 1.14],
"rho_suction": 30.45,
"rho_discharge": 37.65,
"length_unit": "m",
"power_unit": "hp",
"density_unit": "kg/m**3",
},
)
return Report(rotor, config)
def test_from_table():
bearing_file = (os.path.dirname(os.path.realpath(__file__)) +
"/data/bearing_seal.xls")
bearing = BearingElement.from_table(0, bearing_file)
assert bearing.n == 0
assert math.isclose(bearing.w[2], 523.6, abs_tol=0.1)
def test_from_table():
bearing_file = os.path.dirname(
os.path.realpath(__file__)) + "/data/bearing_seal.xls"
bearing = BearingElement.from_table(0, bearing_file)
assert bearing.n == 0
assert bearing.w[2] == 5000
def report1():
# rotor type: single overhung
i_d = 0.0
o_d = 0.05
n = 50
L = [0.03 for _ in range(n)]
shaft_elem = [
ShaftElement(
l,
i_d,
o_d,
material=steel,
shear_effects=True,
rotary_inertia=True,
gyroscopic=True,
)
for l in L
]
disk0 = DiskElement.from_geometry(
n=0, material=steel, width=0.07, i_d=0.05, o_d=0.28
)
stfx = 1e6
stfy = 0.8e6
bearing0 = BearingElement(15, kxx=stfx, kyy=stfy, cxx=1000)
bearing1 = BearingElement(50, kxx=stfx, kyy=stfy, cxx=1000)
rotor = Rotor(shaft_elem, [disk0], [bearing0, bearing1])
# coefficients for minimum clearance
stfx = [0.7e7, 0.8e7, 0.9e7, 1.0e7]
dampx = [2.0e3, 1.9e3, 1.8e3, 1.7e3]
freq = [400, 800, 1200, 1600]
bearing0 = BearingElement(0, kxx=stfx, cxx=dampx, frequency=freq)
bearing1 = BearingElement(6, kxx=stfx, cxx=dampx, frequency=freq)
min_clearance_brg = [bearing0, bearing1]
# coefficients for maximum clearance
stfx = [0.4e7, 0.5e7, 0.6e7, 0.7e7]
dampx = [2.8e3, 2.7e3, 2.6e3, 2.5e3]
freq = [400, 800, 1200, 1600]
bearing0 = BearingElement(0, kxx=stfx, cxx=dampx, frequency=freq)
bearing1 = BearingElement(6, kxx=stfx, cxx=dampx, frequency=freq)
max_clearance_brg = [bearing0, bearing1]
bearing_clearance_lists = [min_clearance_brg, max_clearance_brg]
bearing_stiffness_range = (5, 8)
speed_range = (400, 1000)
tripspeed = 1200
machine_type = "turbine"
units = "rad/s"
return Report(
rotor,
speed_range,
tripspeed,
bearing_stiffness_range,
bearing_clearance_lists,
machine_type,
units,
)
def bearing_constant():
bearing = BearingElement(n=4, kxx=8e7, cxx=0)
return bearing
def stability_level_1(self, D, H, HP, N, RHOd, RHOs, steps=21, unit="m"):
"""Stability analysis level 1.
This analysis consider a anticipated cross coupling QA based on
conditions at the normal operating point and the cross-coupling
required to produce a zero log decrement, Q0.
Components such as seals and impellers are not considered in this
analysis.
Parameters
----------
D : list
Impeller diameter, m (in.),
Blade pitch diameter, m (in.),
H : list
Minimum diffuser width per impeller, m (in.),
Effective blade height, m (in.),
HP : list
Rated power per stage/impeller, W (HP),
N : float
Operating speed, rpm,
RHOd : float
Discharge gas density per impeller, kg/m3 (lbm/in.3),
RHOs : float
Suction gas density per impeller, kg/m3 (lbm/in.3).
steps : int
Number of steps in the cross coupled stiffness range.
Default is 21.
unit : str
Adopted unit system.
Default is "m"
Return
------
Example
-------
"""
if unit == "m":
C = 9.55
elif unit == "in":
C = 63.0
else:
raise TypeError("choose between meters (m) or inches (in)")
if len(D) != len(H):
raise Exception("length of D must be the same of H")
# Qa - Anticipated cross-coupling - API 684 - SP6.8.5.6
if self.machine_type == "compressor":
Bc = 3.0
Dc, Hc = D, H
Qa = 0.0
Qa_list = []
for i in range(len(self.rotor.disk_elements)):
qi = (HP[i] * Bc * C * RHOd) / (Dc[i] * Hc[i] * N * RHOs)
Qa_list.append(qi)
Qa += qi
# Qa - Anticipated cross-coupling - API 684 - SP6.8.5.6
if self.machine_type == "turbine" or self.machine_type == "axial_flow":
Bt = 1.5
Dt, Ht = D, H
Qa = 0.0
Qa_list = []
for i in range(len(self.rotor.disk_elements)):
qi = (HP[i] * Bt * C) / (Dt[i] * Ht[i] * N)
Qa_list.append(qi)
Qa += qi
cross_coupled_stiff = np.linspace(0, 10 * Qa, steps)
log_dec = np.zeros(len(cross_coupled_stiff))
for i, Q in enumerate(cross_coupled_stiff):
bearings = [copy(b) for b in self.rotor.bearing_seal_elements]
if self.rotor_type == "between_bearings":
# cross-coupling introduced at the rotor mid-span
n = np.round(np.mean(self.rotor.nodes))
cross_coupling = BearingElement(n=int(n),
kxx=0,
cxx=0,
kxy=Q,
kyx=-Q)
bearings.append(cross_coupling)
else:
# cross-coupling introduced at overhung disks
for n in self.disk_nodes:
cross_coupling = BearingElement(n=int(n),
kxx=0,
cxx=0,
kxy=Q,
kyx=-Q)
bearings.append(cross_coupling)
aux_rotor = Rotor(
self.rotor.shaft_elements,
self.rotor.disk_elements,
bearings,
self.rotor.rated_w,
)
non_backward = aux_rotor.whirl_direction() != "Backward"
log_dec[i] = aux_rotor.log_dec[non_backward][0]
g = interp1d(cross_coupled_stiff,
log_dec,
fill_value="extrapolate",
kind="quadratic")
stiff = cross_coupled_stiff[-1] * (1 + 1 / (len(cross_coupled_stiff)))
while g(stiff) > 0:
log_dec = np.append(log_dec, g(stiff))
cross_coupled_stiff = np.append(cross_coupled_stiff, stiff)
stiff += cross_coupled_stiff[-1] / (len(cross_coupled_stiff))
Q0 = cross_coupled_stiff[-1]
# CSR - Critical Speed Ratio
CSR = self.maxspeed / self.rotor.run_modal(speed=self.maxspeed).wn[0]
# RHO_mean - Average gas density
RHO_mean = (RHOd + RHOs) / 2
RHO = np.linspace(0, RHO_mean * 5, 201)
Qc = np.piecewise(
RHO,
[RHO <= 16.53, RHO > 16.53, RHO == 60, RHO > 60],
[2.5, lambda RHO: (-0.0115 * RHO + 2.69), 2.0, 0.0],
)
# Plot area
fig1 = figure(
tools="pan, box_zoom, wheel_zoom, reset, save",
title=
"Applied Cross-Coupled Stiffness vs. Log Decrement - (API 684 - SP 6.8.5.10)",
x_axis_label="Applied Cross-Coupled Stiffness, Q (N/m)",
y_axis_label="Log Dec",
x_range=(0, max(cross_coupled_stiff)),
y_range=DataRange1d(start=0),
)
fig1.title.text_font_size = "11pt"
fig1.xaxis.axis_label_text_font_size = "11pt"
fig1.yaxis.axis_label_text_font_size = "11pt"
fig1.line(cross_coupled_stiff,
log_dec,
line_width=3,
line_color=bokeh_colors[0])
fig1.add_layout(
Span(
location=Qa,
dimension="height",
line_color="black",
line_dash="dashed",
line_width=3,
))
if unit == "m":
f = 0.062428
x_label1 = "kg/m³"
x_label2 = "lb/ft³"
if unit == "in":
f = 16.0185
x_label1 = "lb/ft³"
x_label2 = "kg/m³"
fig2 = figure(
tools="pan, box_zoom, wheel_zoom, reset, save",
title="CSR vs. Mean Gas Density - (API 684 - SP 6.8.5.10)",
x_axis_label=x_label1,
y_axis_label="MCSR",
y_range=DataRange1d(start=0),
x_range=DataRange1d(start=0))
fig2.title.text_font_size = "11pt"
fig2.xaxis.axis_label_text_font_size = "11pt"
fig2.yaxis.axis_label_text_font_size = "11pt"
fig2.extra_x_ranges = {"x_range2": Range1d(f * min(RHO), f * max(RHO))}
fig2.add_layout(LinearAxis(x_range_name="x_range2",
axis_label=x_label2,
axis_label_text_font_size="11pt"),
place="below")
fig2.add_layout(
Label(
x=RHO_mean,
y=CSR,
text=self.tag,
text_font_style="bold",
text_font_size="12pt",
text_baseline="middle",
text_align="left",
x_offset=10,
))
for txt, x, y in zip(["Region A", "Region B"], [30, 60], [1.20, 2.75]):
fig2.add_layout(
Label(
x=x,
y=y,
text=txt,
text_font_style="bold",
text_font_size="12pt",
text_baseline="middle",
text_align="center",
))
fig2.line(x=RHO, y=Qc, line_width=3, line_color=bokeh_colors[0])
fig2.circle(x=RHO_mean, y=CSR, size=8, color=bokeh_colors[0])
plot = gridplot([[fig1, fig2]])
return plot
