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section Element

Section

Namespace: Empty

Schema: Empty

Type
Parents
Children
NameOccurrencesDescription
All All
      Element description[0, 1]

Description

      Element name

Name

      Element profileUID

UID of the profile

      Element transformation

Transformation

Attributes
NameTypeRequiredDescription
Attribute externalDataDirectorySimple Type string
Attribute externalDataNodePathSimple Type string
Attribute externalFileNameSimple Type string
Attribute uIDSimple Type IDYes
Remarks

An engine nacelle is defined by sections, where at least one and up to an infinite number of sections can be specified. Lofting of the nacelle surface along the sections is done in cylindrical coordinates. The coordinate origin refers to the center of the fan, i.e. the sections and their profiles are typically shifted in negative x-direction.

Note: In the current CPACS release, transformations are still labeled as Cartesian coordinates. It is current work in progress to explicitly introduce cylindrical coordinates. Until this is implemented in a future CPACS release, the implicit conventions listed below apply:

Translation componentCylindrical coordinate equivalentDescription
xϑ Rotation angle around x
yhHorizontal translation
zrRadial translation

The following example illustrates the setup of a nacelle with 4 sections. These are rotated by 0, 120, 180 and 240 degrees around the x-axis (given by translation/x). To illustrate the possible transformations, the profile of the upper section is shifted slightly further in the negative x-direction (translation/y), while the lower section has a smaller radial distance from the rotation axis (translation/z). In addition, the sections are scaled differently (transformation/scaling; not shown in the example figures) in order to create a straight trailing edge and to realize a flattened profile near the ground.

The following example also shows the profile cut-outs due to the radially symmetric inner region of the nacelle defined by therotationCurve. For detailed information, please refer to the documentation of the rotationCurve element.

Nacelle sections

The first section is not rotated (x=ϑ=0), but shifted vertically in negative direction (y=h=-0.257). The radial distance is given by z=r=0.365:

Upper section at 0°
<section uID="fanCowl_upperSection">
    <name>Upper section</name>
    <transformation>
        <scaling>
            <x>1.055</x>
            <y>1</y>
            <z>1</z>
        </scaling>
        <translation>
            <x>0.0</x>
            <y>-0.257</y>
            <z>0.365</z>
        </translation>
    </transformation>
    <profileUID>fanCowlUpperSectionProfile</profileUID>
</section>

The second section is rotated around the x-axis (x=ϑ=120) as well as scaled by a factor of 1.1 in its profile height:

Inboard section at 120° (identical to outboard section at 240°)
<section uID="fanCowl_inboardSection">
    <name>Inboard section</name>
    <transformation>
        <scaling>
            <x>1</x>
            <y>1</y>
            <z>1.1</z>
        </scaling>
        <translation>
            <x>120.0</x>
            <y>-0.2</y>
            <z>0.365</z>
        </translation>
    </transformation>
    <profileUID>fanCowlUpperSectionProfile</profileUID>
</section>

The third section is rotated around the x-axis by 180° and scaled by a factor of 0.8 in its profile height:

Lower section at 180°
<section uID="fanCowl_lowerSection">
    <name>Lower section</name>
    <transformation>
        <scaling>
            <x>1</x>
            <y>1</y>
            <z>0.8</z>
        </scaling>
        <translation>
            <x>180.0</x>
            <y>-0.2</y>
            <z>0.33</z>
        </translation>
    </transformation>
    <profileUID>fanCowlUpperSectionProfile</profileUID>
</section>
See Also