Jerry
153 lines
5.1 KiB
Python
153 lines
5.1 KiB
Python
from math import asin, cos, hypot, radians, sin, tau
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from build123d import (
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Align,
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BuildPart,
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BuildSketch,
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Cylinder,
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Location,
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Locations,
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Mode,
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Plane,
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Polygon,
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add,
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extrude,
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)
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from benchmark_common import circular_edges, polar_point, safe_fillet
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BACKPLATE_DIAMETER = 90.0
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BACKPLATE_THICKNESS = 6.0
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BACKPLATE_FILLET = 1.5
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HUB_DIAMETER = 26.0
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HUB_HEIGHT = 22.0
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BORE_DIAMETER = 8.0
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BLADE_COUNT = 12
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BLADE_ROOT_RADIUS = 18.0
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BLADE_TIP_RADIUS = 43.0
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BLADE_THICKNESS = 3.0
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BLADE_HEIGHT = 16.0
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BLADE_BACKWARD_SWEEP = radians(45.0)
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BLADE_SEGMENTS = 5
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BLADE_ROOT_FILLET = 1.0
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def _clamp_radius(point: tuple[float, float]) -> tuple[float, float]:
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radius = hypot(point[0], point[1])
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if radius < BLADE_ROOT_RADIUS:
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scale = BLADE_ROOT_RADIUS / radius
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return (point[0] * scale, point[1] * scale)
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if radius > BLADE_TIP_RADIUS:
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scale = BLADE_TIP_RADIUS / radius
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return (point[0] * scale, point[1] * scale)
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return point
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def _blade_center(base_angle: float, t: float) -> tuple[float, float]:
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radius = BLADE_ROOT_RADIUS + (BLADE_TIP_RADIUS - BLADE_ROOT_RADIUS) * t
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angle = base_angle - BLADE_BACKWARD_SWEEP * t
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return polar_point(radius, angle)
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def _blade_normal(base_angle: float, t: float) -> tuple[float, float]:
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radius = BLADE_ROOT_RADIUS + (BLADE_TIP_RADIUS - BLADE_ROOT_RADIUS) * t
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dr_dt = BLADE_TIP_RADIUS - BLADE_ROOT_RADIUS
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dtheta_dt = -BLADE_BACKWARD_SWEEP
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angle = base_angle + dtheta_dt * t
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dx_dt = dr_dt * cos(angle) - radius * sin(angle) * dtheta_dt
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dy_dt = dr_dt * sin(angle) + radius * cos(angle) * dtheta_dt
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length = hypot(dx_dt, dy_dt)
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return (-dy_dt / length, dx_dt / length)
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def _blade_end_points(base_angle: float, t: float) -> tuple[tuple[float, float], tuple[float, float]]:
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radius = BLADE_ROOT_RADIUS if t == 0.0 else BLADE_TIP_RADIUS
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angle = base_angle - BLADE_BACKWARD_SWEEP * t
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half_angle = asin((BLADE_THICKNESS / 2.0) / radius)
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return (polar_point(radius, angle + half_angle), polar_point(radius, angle - half_angle))
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def _blade_outline(base_angle: float) -> list[tuple[float, float]]:
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left_side = []
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right_side = []
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half_thickness = BLADE_THICKNESS / 2.0
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for index in range(BLADE_SEGMENTS + 1):
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t = index / BLADE_SEGMENTS
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if index == 0 or index == BLADE_SEGMENTS:
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left, right = _blade_end_points(base_angle, t)
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else:
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center = _blade_center(base_angle, t)
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normal = _blade_normal(base_angle, t)
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left = _clamp_radius((center[0] + normal[0] * half_thickness, center[1] + normal[1] * half_thickness))
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right = _clamp_radius((center[0] - normal[0] * half_thickness, center[1] - normal[1] * half_thickness))
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left_side.append(left)
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right_side.append(right)
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return left_side + list(reversed(right_side))
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def _make_blade(index: int):
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base_angle = tau * index / BLADE_COUNT
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with BuildPart() as blade:
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with BuildSketch(Plane.XY):
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Polygon(_blade_outline(base_angle), align=None)
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extrude(amount=BLADE_HEIGHT)
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part = blade.part.moved(Location((0.0, 0.0, BACKPLATE_THICKNESS)))
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part.label = f"backward_curved_blade_{index + 1:02d}"
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return part
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def _blade_root_edges(part):
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edges = []
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for edge in part.edges():
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bbox = edge.bounding_box()
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center = bbox.center()
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if abs(center.Z - BACKPLATE_THICKNESS) > 0.05:
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continue
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radial_distance = hypot(center.X, center.Y)
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if BLADE_ROOT_RADIUS - 3.0 <= radial_distance <= 30.0:
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if str(edge.geom_type).endswith("LINE"):
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edges.append(edge)
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return edges
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def gen_step():
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"""Return the centrifugal impeller benchmark model in millimeters."""
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total_height = BACKPLATE_THICKNESS + HUB_HEIGHT
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with BuildPart() as impeller:
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Cylinder(
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radius=BACKPLATE_DIAMETER / 2.0,
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height=BACKPLATE_THICKNESS,
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align=(Align.CENTER, Align.CENTER, Align.MIN),
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)
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for blade_index in range(BLADE_COUNT):
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add(_make_blade(blade_index), mode=Mode.ADD)
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with Locations(Location((0.0, 0.0, BACKPLATE_THICKNESS))):
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Cylinder(
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radius=HUB_DIAMETER / 2.0,
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height=HUB_HEIGHT,
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align=(Align.CENTER, Align.CENTER, Align.MIN),
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mode=Mode.ADD,
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)
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with Locations(Location((0.0, 0.0, -1.0))):
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Cylinder(
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radius=BORE_DIAMETER / 2.0,
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height=total_height + 2.0,
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align=(Align.CENTER, Align.CENTER, Align.MIN),
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mode=Mode.SUBTRACT,
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)
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part = impeller.part
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backplate_edges = []
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backplate_edges.extend(circular_edges(part, radius=BACKPLATE_DIAMETER / 2.0, axis="z", coordinate=0.0))
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backplate_edges.extend(circular_edges(part, radius=BACKPLATE_DIAMETER / 2.0, axis="z", coordinate=BACKPLATE_THICKNESS))
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part = safe_fillet(part, backplate_edges, radius=BACKPLATE_FILLET)
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part = safe_fillet(part, _blade_root_edges(part), radius=BLADE_ROOT_FILLET)
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part.label = "benchmark_08_centrifugal_impeller_backward_curved_blades"
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return part
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