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2026-07-22 13:48:46 +08:00
commit c87751c3dc
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+// Axial-Flow Turbine Blisk
+// A parametric model of a jet engine compressor stage
+
+/* [Blisk Dimensions] */
+// Number of blades around the hub
+num_blades = 28;           // [10:1:60]
+// Outer radius of the central hub
+hub_radius = 45;           // [20:1:100]
+// Radius of the central shaft hole
+bore_radius = 12;          // [5:1:30]
+// Radial height of each blade
+blade_height = 45;         // [20:1:100]
+
+/* [Hub Profile] */
+// Thickness of the hub at the center
+hub_center_thickness = 30; // [10:1:60]
+// Thickness of the hub at the rim
+hub_rim_thickness = 22;    // [10:1:50]
+// Width of the collar around the bore
+flange_width = 8;          // [0:1:20]
+// Height of the collar around the bore
+flange_height = 5;         // [0:1:20]
+
+/* [Blade Aerodynamics] */
+// Length of the blade profile (chord)
+blade_chord = 22;          // [10:1:50]
+// Angle of the blade at the root
+root_stagger = 30;         // [0:1:90]
+// Total twist from root to tip
+blade_twist = 35;          // [-60:1:60]
+// Aerodynamic camber (curvature)
+camber_pct = 10;           // [0:1:20]
+// Maximum thickness of the blade profile
+thickness_pct = 6;         // [2:1:15]
+
+/* [Settings] */
+blisk_color = "#A8AEB3";
+$fn = 72;
+
+// --- Main Model ---
+
+color(blisk_color)
+difference() {
+    union() {
+        hub();
+        blade_array();
+    }
+    // Central bore keyway to lock the blisk to a shaft
+    translate([bore_radius + 1.5, 0, 0])
+    cube([4, 6, hub_center_thickness * 3], center=true);
+}
+
+// --- Modules ---
+
+module hub() {
+    // Generates the profiled central disk
+    rotate_extrude(convexity = 4)
+    polygon([
+        [bore_radius, hub_center_thickness/2 + flange_height],
+        [bore_radius + flange_width, hub_center_thickness/2 + flange_height],
+        [bore_radius + flange_width, hub_center_thickness/2],
+        [hub_radius, hub_rim_thickness/2],
+        [hub_radius, -hub_rim_thickness/2],
+        [bore_radius + flange_width, -hub_center_thickness/2],
+        [bore_radius + flange_width, -hub_center_thickness/2 - flange_height],
+        [bore_radius, -hub_center_thickness/2 - flange_height]
+    ]);
+}
+
+module blade_array() {
+    // Radial array of aerofoil blades
+    for (i = [0 : num_blades - 1]) {
+        rotate([0, 0, i * 360 / num_blades])
+        // Embed the blade root slightly into the hub rim
+        translate([hub_radius - 2, 0, 0])
+        // Lay the blade down so it points outward radially
+        rotate([0, 90, 0]) 
+        // Extrude with aerodynamic twist
+        linear_extrude(height = blade_height + 2, twist = blade_twist, slices = 45, convexity = 2)
+        // Set the root angle (stagger)
+        rotate([0, 0, root_stagger])
+        // Center the aerofoil on the extrusion axis
+        translate([-blade_chord/2, 0])
+        naca_airfoil(blade_chord, thickness_pct, camber_pct, 40);
+    }
+}
+
+module naca_airfoil(c, t_pct, m_pct, p_pct) {
+    // Generates a robust NACA-style highly cambered profile
+    t_val = t_pct / 100;
+    m = m_pct / 100;
+    p = p_pct / 100;
+
+    // Thickness distribution function
+    function y_t(x) = 5 * t_val * c * (0.2969*sqrt(abs(x/c)) - 0.1260*(x/c) - 0.3516*pow(x/c,2) + 0.2843*pow(x/c,3) - 0.1015*pow(x/c,4));
+
+    // Camber line function
+    function y_c(x) = (m == 0) ? 0 :
+        ( (x/c) <= p ) ? m * c / pow(p,2) * (2*p*(x/c) - pow(x/c,2))
+                       : m * c / pow(1-p,2) * ((1-2*p) + 2*p*(x/c) - pow(x/c,2));
+
+    // Camber gradient for normal vector
+    function dy_c(x) = (m == 0) ? 0 :
+        ( (x/c) <= p ) ? 2 * m / pow(p,2) * (p - (x/c))
+                       : 2 * m / pow(1-p,2) * (p - (x/c));
+
+    function theta(x) = atan(dy_c(x));
+
+    steps = 30; // Resolution per side
+    
+    // Generate upper surface points
+    pts_upper = [ for (i=[0:steps])
+        let (
+            x = c * (1 - cos(i * 180 / steps))/2,
+            yt = y_t(x),
+            yc = y_c(x),
+            th = theta(x)
+        )
+        [ x - yt * sin(th), yc + yt * cos(th) ]
+    ];
+
+    // Generate lower surface points
+    pts_lower = [ for (i=[steps:-1:0])
+        let (
+            x = c * (1 - cos(i * 180 / steps))/2,
+            yt = y_t(x),
+            yc = y_c(x),
+            th = theta(x)
+        )
+        [ x + yt * sin(th), yc - yt * cos(th) ]
+    ];
+
+    // Combine and apply offset to guarantee manifold trailing edges and robust printability
+    offset(r=0.6)
+    polygon(concat(pts_upper, pts_lower));
+}