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Public Domain Aeronautical Software (PDAS)  

VuCalc is based on a program of the same name written by Tom Benson of NASA Glenn as an aid to making calculations in compressible fluid dynamics. There are six screens, each of which performs a different class of calculations.

Isentropic Flow
Normal Shock
Oblique Shock
Standard Atmosphere
Rayleigh Flow
Fanno Flow

Isentropic Flow

The isentropic flow page enables the user to calculate the total temperature ratio, total pressure ratio, total density ratio, area ratio, Mach angle and Prandtl-Meyer function for any Mach number. In addition, the values of any one of these quantities may be specified and VuCalc will solve for the corresponding Mach number and the remaining quantities.
Screen Shot

Normal Shock

The ratios of downstream to upstream values of various quantities may be computed for any Mach number. As with the isentropic flow page, the value of any flow parameter may be specified and VuCalc will calculate the corresponding Mach number and all other quantities.
Screen Shot

Oblique Shock

The oblique shock problem has an additional degree of freedom in specifying the problem. In this case, the user supplies the upstream Mach number and one of the following variables: ramp angle, wave angle, total pressure ratio, static pressure ratio, temperature ratio, density ratio or downstream Mach number. The other variables will then be computed and displayed. Of course, there are many cases for which there is no solution with an attached shock.
Screen Shot

Standard Atmosphere

A flight condition in the standard atmosphere is specified by the altitude and Mach number. For these conditions, the values of velocity, temperature, density, pressure, speed of sound, unit Reynolds number, viscosity, dynamic pressure are computed and displayed. SI or US units may be used for input. When switching between SI and US units, the previous case is remembered and the appropriate values are shown for the other set of units.
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Rayleigh Flow

The flow condition known as Rayleigh Flow assumes that the flow is in a constant-area duct without friction but with heat transfer. This type of flow turns out to be a good approximation of heat exchangers and of constant-area combustion chambers such as is typical of gas turbines. Typical tables of Rayleigh Flow show ratios of various thermodynamic flow quantities at a given Mach number to the value of this same quantity at a Mach number of 1.0 with the flow modified by heat transfer without friction. Typical quantities are static temperature, total temperature, static pressure, total pressure, density, and velocity. As on the other pages, one may select a given value of any flow parameter and command VuCalc to compute the coressponding Mach number as well as the remaining flow parameters.
Screen Shot

Fanno Flow

Fanno flow assumes flow in a constant-area duct with friction but without heat transfer. As on the other pages, one may select a given value of any flow parameter and command VuCalc to compute the coressponding Mach number as well as the remaining flow parameters.
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Usage

The program may be used as supplied, but because the source code is included, the functions that compute the flow quantities are available for inclusion in your own computing projects. The flow ratios in terms of Mach number are straightforward codings of the equations in NACA Report 1135 or any gas dynamics textbook. The inverse relations can sometimes be solved by algebraic manipulation, but must be computed by numerical root finding in others.

A Web-based Java Approach

There is a similar calculator developed by William Devenport of Virginia Tech. Instead of being a Windows application (like VuCalc), it is a Java applet that runs in your web browser, provided you have a Java-enabled browser.
There is an interesting supersonic airfoil page written by Evgeni Kudriavitski that uses the oblique shock and Prandtl-Meyer expansion functions to compute the inviscid aerodynamic force on a wedge airfoil with attached shocks. It is very instructive to reshape the wing or change the angle of attack and watch the pressures and forces recompute. This is implemented as a java applet and runs on your browser. He has made the applet available for download, so you can run the applet even if you are not connected to the web. Note: As of February 2013, this seems to have disappeared. If anyone knows its new address, I will be happy to update this page.

This program was not released by NASA through COSMIC. The source code for the C version of Vu-Calc with graphical interface for a Silicon Graphics workstation was obtained from NASA Lewis (now Glenn). The code was converted to Pascal and the Delphi interface for Microsoft Windows by Public Domain Aeronautical Software. All value added by PDAS is placed in the public domain.

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Public Domain Aeronautical Software (PDAS)