This
is a beta 1.3e version of the ShockSim program, and you are invited
to participate in the beta testing. If you find errors in the program or
would like to suggest improvements, please send an e-mail to nancy.r.hall@nasa.gov.
Due to IT
security concerns, many users are currently experiencing problems running NASA Glenn
educational applets. There are
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this problem.
ShockSim
With this software you can investigate how shock waves
are formed by the
supersonic flow
of a gas past a
wedge
or a
cone.
Depending on the Mach number and the size of object,
attached oblique
shocks, or
detached
normal shocks are formed at the leading edge of the object.
You can study this flow by
interactively changing the values of different input parameters.
There are several different software packages available at the
Beginner's Guide to Compressible Aerodynamics to study the
generation of oblique or normal shock waves.
This web page contains the on-line version of the single shock program.
It includes an on-line user's manual which describes the
various options available in the program and includes hyperlinks to
pages in the
Beginner's Guide to Compressible Flow
and
NASA's Guide to Hypersonics
describing the math and science of shock waves.
More experienced users can select a
version of the program which does not include
these instructions and loads faster on your computer.
There are two separate packages which solve for flow past a supersonic
cone and a supersonic
wedge.
There is also a special program to solve for
multiple shock waves
with shock reflections and intersections. The multiple shock program
also solves for Prandtl-Meyer
expansions which occur when the flow is
turned into an expanding region.
You can download these programs to your computer
by clicking on this yellow button:
With the downloaded version, you can run the programs off-line and do not
have to be connected to the Internet.
If you see only a grey box at the top of this page, be sure that Java is
enabled in your browser. If Java is enabled, and you are using the Windows XP
operating system, you need to get a newer version of Java. Go to this link:
http://www.java.com/en/index.jsp,
try the "Download It Now" button, and then select "Yes" when the download box from Sun
pops up.
If you experience difficulties when using the sliders to change variables,
simply click away from the slider and then back to it.
If
the arrows on the end of the sliders disappear, click in the areas
where the left and right arrow images should appear, and they
should reappear.
GENERAL INSTRUCTIONS
This program is designed to be interactive, so you have to work with the program.
You choose a particular flow problem by clicking on the white
choice button at the upper right of the program. You can choose between flow past a wedge
and flow past a cone.
The current value of flow variables are presented to you in boxes.
By convention, a white box with
black numbers is an input box and you can change the value of the number.
To change the value in an input box, select the box by moving the cursor into the box
and clicking the mouse, then backspace over the old number, enter a new number,
then hit the Enter key on your keyboard. You must hit Enter
to send the new value to the program.
For most input variables you can also use a slider located next to the input box.
Click on the slider bar, hold down and drag the slider bar to change values, or
you can click on the arrows at either end of the slider.
A black box with
yellow numbers is an output box and the value is computed by the program.
There are some choices which you must make regarding the display
of computed results by using a choice box.
A choice box has a descriptive word displayed and an arrow at the right of the
box. To make a choice, click on the arrow, hold down and drag to
make your selection.
SCREEN
The
program screen is divided into three main parts:
At the
left of the screen is a graphic of the wedge or cone and
shock waves that you are studying.
On the
upper right side of the screen is the input panel.
On the
lower right side of the screen are the results of
the calculations.
GRAPHICS
WINDOW
On the graphics display, supersonic flow is from left to right.
The wedge or cone is shown in red.
Oblique shock waves are drawn as blue lines.
Normal shocks are colored magenta. For the conical flow problem, flow
variables are constant along rays of a cone starting at the leading edge.
The rays are shown in blue. You can choose to display the values of the flow variables
for a particular ray on the output panel. The ray that you choose is shown
in red on the graphics panel.
Streamlines from upstream and flowing through the shock waves are shown in black.
NUMERICAL
INPUT
Numerical
input to the program is entered at the upper right.
You can specify the free stream
Mach number by using either the
input box or the slider. You can also specify the angles for the
wedge or cone. The
gamma variable is the ratio of
specific heats
of the gas.
NUMERICAL
OUTPUT
Numerical
output from the program is displayed at the lower right.
The output for the conical flow is displayed by Rays,
with each ray beginning at the tip of the cone.
You select which ray to display by using the white and blue
choice button.
The output variables on the right
are referenced to flow upstream of the shock,
which are the free stream conditions.
Mach
below the Ray button is the
Mach number
on the surface of the cone. Mach to the
right of the zone button is the Mach number along the selcted ray.
Angle is the angle of the selected ray,
while Turning is the total amount that
the flow has been turned relative to free stream direction.
Shock Angle is
the angle of the shock wave. The static and total
pressure ratio
are listed, followed by the
temperature
and
density
ratios. For the cone, these values are calculated using the
oblique or
normal
shock relations, followed by an
isentropic compression to the ray Mach number.
The ray Mach number is determined by the
Taylor-Maccoll analysis,
For the wedge problem, flow variable values are determined by the
oblique or
normal
shock relations.
NEW
FEATURES
The
Educations Program Office will continue to improve and update
ShockModeler based on user input. Changes from previous versions of
the program include:
On 12 Sep
11 version 1.3e was released. This version of the program was the first
release of the computer program. The version number reflects the fact that
the program was derived from Version 1.2 of the single wedge shock program. The
addition of the Taylor-Maccoll analysis for the cone has lead to a re-organization
of the information at the compressible flow web site. Versions 1.3a-1.3d were
developmental versions of the program and not released to the public.
