aerosandbox.library.aerodynamics.transonic
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Module Contents#
Functions#
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Yields the idealized drag area (denoted CDA, or equivalently, D/q) of a Sears-Haack body. |
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See documentation for sears_haack_drag() in this same file. |
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Wave drag_force coefficient prediction using the low-fidelity Korn Equation method; |
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Wave drag_force coefficient prediction using the low-fidelity Korn Equation method; |
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An approximate relation for computing transonic wave drag, based on an object's Mach number. |
Attributes#
- aerosandbox.library.aerodynamics.transonic.sears_haack_drag(radius_max, length)[source]#
Yields the idealized drag area (denoted CDA, or equivalently, D/q) of a Sears-Haack body.
Assumes linearized supersonic (Prandtl-Glauert) flow.
https://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body
Note that drag coefficient and drag area are independent of Mach number for this case (assuming linearized supersonic aero).
- Parameters:
radius_max (float) – The maximum radius of the Sears-Haack body.
length (float) – The length of the Sears-Haack body.
- Return type:
float
Returns: The drag area (CDA, or D/q) of the body. To get the drag force, multiply by the dynamic pressure.
- aerosandbox.library.aerodynamics.transonic.sears_haack_drag_from_volume(volume, length)[source]#
See documentation for sears_haack_drag() in this same file.
Identical, except takes volume as an input rather than max radius.
Also returns a drag area (denoted CDA, or equivalently, D/q).
- Parameters:
volume (float) –
length (float) –
- Return type:
float
- aerosandbox.library.aerodynamics.transonic.mach_crit_Korn(CL, t_over_c, sweep=0, kappa_A=0.95)[source]#
Wave drag_force coefficient prediction using the low-fidelity Korn Equation method;
derived in “Configuration Aerodynamics” by W.H. Mason, Sect. 7.5.2, pg. 7-18
- Parameters:
CL – Sectional lift coefficient
t_over_c – thickness-to-chord ratio
sweep – sweep angle, in degrees
kappa_A – Airfoil technology factor (0.95 for supercritical section, 0.87 for NACA 6-series)
Returns:
- aerosandbox.library.aerodynamics.transonic.Cd_wave_Korn(Cl, t_over_c, mach, sweep=0, kappa_A=0.95)[source]#
Wave drag_force coefficient prediction using the low-fidelity Korn Equation method; derived in “Configuration Aerodynamics” by W.H. Mason, Sect. 7.5.2, pg. 7-18
- Parameters:
Cl – Sectional lift coefficient
t_over_c – thickness-to-chord ratio
sweep – sweep angle, in degrees
kappa_A – Airfoil technology factor (0.95 for supercritical section, 0.87 for NACA 6-series)
- Returns:
Wave drag coefficient
- aerosandbox.library.aerodynamics.transonic.approximate_CD_wave(mach, mach_crit, CD_wave_at_fully_supersonic)[source]#
An approximate relation for computing transonic wave drag, based on an object’s Mach number.
Considered reasonably valid from Mach 0 up to around Mach 2 or 3-ish.
Methodology is a combination of:
The methodology described in Raymer, “Aircraft Design: A Conceptual Approach”, Section 12.5.10 Transonic Parasite Drag (pg. 449 in Ed. 2)
and
The methodology described in W.H. Mason’s Configuration Aerodynamics, Chapter 7. Transonic Aerodynamics of Airfoils and Wings.
- Parameters:
mach – Mach number at the operating point to be evaluated
mach_crit – Critical mach number, a function of the body geometry
CD_wave_at_fully_supersonic – The wave drag coefficient of the body at the speed that it first goes (
supersonic. (effectively) fully) –
Here, that is taken to mean at the Mach 1.2 case.
This value should probably be derived using something similar to a Sears-Haack relation for the body in question, with a markup depending on geometry smoothness.
The CD_wave predicted by this function will match this value exactly at M=1.2 and M=1.05.
The peak CD_wave that is predicted is ~1.23 * this value, which occurs at M=1.10.
In the high-Mach limit, this function asymptotes at 0.80 * this value, as empirically stated by Raymer. However, this model is only approximate and is likely not valid for high-supersonic flows.
Returns: The approximate wave drag coefficient at the specified Mach number.
The reference area is whatever the reference area used in the CD_wave_at_fully_supersonic parameter is.