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# Nacelle CASD Tutorial

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### Transcript

• 1. This example shows a step-by-step creation of a Cylindrical Arbitrary Shape Deformation (CASD) Volume for the deformation of a CFD mesh model of an aircraft engine nacelle. Several different deformations of the Nacelle&#x2019;s leading edge are performed to show how to define shape change variables (i.e. Sculptor Groups) for different types of desired deformations. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 2. The CFD mesh model of an aircraft engine nacelle is imported into Sculptor. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 3. The initial CASD volume is created with 4 control points in the r-direction (radial), 12 around the &#x3B8; direction, and 10 along the u-direction (axial). &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 4. The r-&#x3B8; planes are positioned (translated) along the u-direction. Judicious placement of control points helps define and constrain the desired deformations locally. Note: the 4th and 5th planes from the front (left) are placed so that any control points in the 3rd plan will not deform any geometry to the aft (right) of the 5th plane. This is so that we do not want to deform the internal engine geometry while we deform/optimize the nacelle inlet shape. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 5. The r-positions are modified by translating the 2nd and 3rd r-u &#x2018;cross-section planes&#x2019; along the r-direction. Again, judicious placement of control points helps define and constrain the desired deformations locally. Note: each cross-section plane is modified so that the 3rd r-u plane (denoted t,u#3 in the dialog) just follows the exterior contour of the nacelle. The 2nd r-u plane is moved to just inside the 3rd plane close enough to use these two internal planes to control the shape of the inlet. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 6. Now that the control points are in their desire positions, we freeze the CASD volume. This can take time since the freezing algorithm is more complex for CASD volumes than regular ASD volumes. One can speed this up by selecting more threads in the Preference Dialog under the File Menu. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 7. For clarity, the Inactive Control Points&#x2019; visibility was removed from this view. In this case, all of the outer r control points (i.e. &#x3B8;-u plane # 4), as well as the control points in the first two and last two r-&#x3B8; planes were defined as Inactive (picked with the mouse with the &#x2018;blue&#x2019; highlight). &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 8. The Create Group dialog was used to create several Groups to be used as shape change design variables. First a Group is created to rotate the nacelle inlet about a horizontal vector across the inlet face. Another Group is created to change the length of the inlet. And a third Group is created to change the radius of the inlet. The effect of these Groups are shown in following slides. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 9. a) Undeformed b) Inlet expanded c) Inlet contracted The highlighted control points (in yellow) were defined as a Group to control the size of the nacelle inlet. A single design variable is changed to expand and contract the inlet diameter while maintaining its circular shape. Images showing the nacelle with and without surface cells for the a) initial shape (undeformed), b) expanded shape, and c) contracted shape. Due to the smooth volumetric deformation, the cell quality remains very high. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 10. a) Undeformed b) Inlet expanded c) Inlet contracted The highlighted control points (in yellow) were defined as a Group to control the size of the nacelle inlet. A single design variable is changed to expand and contract the inlet diameter while maintaining its circular shape. Images showing the nacelle with and without surface cells for the a) initial shape (undeformed), b) expanded shape, and c) contracted shape. Due to the smooth volumetric deformation, the cell quality remains very high. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 11. a) Undeformed b) Inlet expanded c) Inlet contracted The highlighted control points (in yellow) were defined as a Group to control the size of the nacelle inlet. A single design variable is changed to expand and contract the inlet diameter while maintaining its circular shape. Images showing the nacelle with and without surface cells for the a) initial shape (undeformed), b) expanded shape, and c) contracted shape. Due to the smooth volumetric deformation, the cell quality remains very high. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.
• 12. These shapes shown here are more examples of smooth arbitrary shape deformations on the nacelle inlet. Most solutions to shape optimization (using ASDs and CASDs) are small subtle shape changes. However, large deformations can also be made and still keep the cell quality within limits. &#xA9; Copyright 2009 Optimal Solutions All rights reserved.