FRICTION Analysis Interface Module (AIM)
FRICTION Analysis Interface Module (AIM)
|
This is a walkthrough for using FRICTION AIM to analyze a wing, tail, fuselage configuration.
It is presumed that ESP and CAPS have been already installed, as well as FRICTION. Furthermore, a user should have knowledge on the generation of parametric geometry in Engineering Sketch Pad (ESP) before attempting to integrate with any AIM. Specifically this example makes use of Design Parameters, Set Parameters, User Defined Primitive (UDP) and attributes in ESP.
Two scripts are used for this illustration:
The CSM script generates Bodies which are designed to be used by specific AIMs. The AIMs that the Body is designed for is communicated to the CAPS framework via the “capsAIM” string attribute. This is a semicolon-separated string with the list of AIM names. Thus, the CSM author can give a clear indication to which AIMs should use the Body. In this example, the list contains only the frictionAIM:
FRICTION input is always in feet, to enable automatic conversion, the geometric attribute capsLength may be used to define the units the geometry (*.csm) file is in.
Next we will define the design parameters to define the wing cross section and planform.
The design parameters will then be used to set parameters for use internally to create geometry.
Next the Wing, Vertical and Horizontal tails are created using the naca User Defined Primitive (UDP). The inputs used for this example to the UDP are Thickness and Camber. The naca sections generated are in the X-Y plane and are rotated to the X-Z plane. They are then translated to the appropriate position based on the design and set parameters defined above. Finally reference area can be given to the FRICTION AIM by using the capsReferenceArea attribute. If this attribute exists on any body that value is used otherwise the default is 1.0.
In addition, each section has a capsType attribute. This is used to logically group sections together. More information on this can be found in the AIM Attributes section.
Vertical Tail definition
Horizontal Tail definition
Fuselage definition. Notice the use of the ellipse UDP. In this case, only translation is required to move the cross section into the desired location.
An example pyCAPS script that uses the above *.csm file to run FRICTION is as follows.
First the pyCAPS and os module needs to be imported.
Once the modules have been loaded the problem needs to be initiated.
Next the *.csm file is loaded and design parameter is changed - area in the geometry. Any despmtr from the frictionWingTailFuselage.csm file is available inside the pyCAPS script. They are: thick, camber, area, aspect, taper, sweep, washout, dihedral...
Next local variables used throughout the script are defined.
The FRICTION AIM is then loaded with:
After the AIM is loaded, the Mach number and Altitude are set (see AIM Inputs for additional inputs). The FRICTION AIM supports variable length inputs. For example 1 or 10 or more, Mach and Altitude pairs can be entered. The example below shows two inputs. Note that the length of the Mach and Altitude inputs must be the same.
Once all the inputs have been set, preAnalysis needs to be executed. During this operation, all the necessary files to run FRICTION are generated and placed in the analysis working directory (analysisDir).
At this point the required files necessary run FRICTION should have been created and placed in the specified analysis working directory. Next FRICTION needs to executed such as through an OS system call (see FRICTION AIM Overview for additional details) like,
A call to postAnalysis is then made to check to see if FRICTION executed successfully and the expected files were generated.
Similar to the AIM inputs, after the execution of FRICTION and postAnalysis, any of the AIM's output variables (AIM Outputs) are readily available; for example,
Printing the above variables results in,