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ShockModeler Version 1.3a

Glenn
Research
Center

This is a beta 1.3a version of the ShockModeler 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 security settings that you can adjust that may correct this problem.

ShockModeler

With this software you can investigate how shock waves are formed and interact with other shock waves in a supersonic or hypersonic flow by interactively changing the values of different parameters.

There are several different versions of ShockModeler which require different levels of experience with the package, knowledge of compressible flows, and computer technology. This web page contains the on-line version of the 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 NASA's Guide to Hypersonics and Beginner's Guide to Compressible Flow 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. You can download these versions of the program to your computer by clicking on this yellow button:

Button to Download a Copy of the Program

With the downloaded version, you can run the program off-line and do not have to be connected to the Internet.

There is a special version of ShockModeler that deals only with the single oblique or normal shock formed by a wedge or cone.

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 buttons on the blue bar at the top of the program. 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. At any time, to return to the original default conditions, click the white and red Reset button on the blue bar.

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.

SCREEN

The program screen is divided into three main parts:

  1. At the top of the screen is a graphic of the wedges and shock waves that you are studying.
  2. On the lower left side of the screen is the input panel.
  3. On the lower right side of the screen are the results of the calculations.

GRAPHICS WINDOW

You can choose from three different flow problems using the buttons on the blue bar at the top of the graphics window: a single wedge, a double wedge in series, or opposed wedges. For the single shock, you may generate an attached oblique shock, a detached normal shock, or an expansion fan, depending on the choice of wedge angle and free stream Mach number. For the double and opposed wedges you generate shock-on-shock interactions. For the opposed wedges, you generate reflected shock waves.

On the graphics display, supersonic flow is from left to right. The wedges are numbered with black numerals that correspond to the wedge angle numbers on the input panel. The red wedge is wedge #1 and the green wedge is wedge #2. Oblique shock waves are drawn as blue lines with a numeral near the middle of the line. (For some highly inclined lines, it may be difficult to read the shock number.) Normal shocks are colored magenta, and the beginning and end of an expansion fan are drawn as black lines. For shock-on-shock interactions, slip lines (or shear layers) are often generated. The static pressure is constant across a slip line although the Mach number changes. Slip lines are drawn in black on the graphic. You can Zoom in for a closer look at the graphic by using the slider bar at the left. You can also move the graphic by clicking in the window, holding down on the left mouse button and dragging the graphic to a desired location. If you lose the graphic, you can bring it back to its default position and size by clicking on the "Find" button on the blue bar. The "Reset" button will also set the input conditions to their default values.

NUMERICAL INPUT

Numerical input to the program is entered at the lower left. 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 wedges. Again, angle #1 sets the size of the red wedge, angle #2 sets the green wedge for the double wedge and opposed wedge problems. For the multiple wedge problems you must also specify the distance between the wedges. This input is given by the Spacing variable. 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 is displayed by Zones, with each zone being the flow domain downstream of a shock wave or expansion fan. The shocks are numbered on the graphic with a blue numeral; the zone number corresponds to the shock number. You select which zone to display by using the white and red zone choice button. The output variables on the left are referenced to flow upstream of the shock, while the variables on the right are referenced to free stream conditions. Mach below the Zone button is the Mach number of the flow in the specified zone, Mach-up to the right of the zone button is the Mach number upstream of the shock wave. Angle is the wedge angle that is generating the shock in the selected zone, while Turning is the total amount that the flow has been turned relative to free stream. Shock is the shock angle. The static and total pressure ratio are listed, followed by the temperature and density ratios. These values are calculated using 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:

  1. On 18 Feb 11 version 1.3a was released. This version of the program has imposed some limits on the downtream Mach number for a centered expansion fan. Any Mach number greater than 50 is reset to M=50. This avoids the appearance of pressure ratios equal to zero. Textbooks and NACA 1135 put similar artificial limits on the downstream Mach number and Prandtl-Meyer angle. Prandtl-Meyer maximum value is [ pi/2 * (sqrt((gamma+1)/(gamma-1))-1) ] which gives an infinite Mach number.
  2. On 14 Apr 06 version 1.2a was released. The name and layout of the program was changed and the input manual was developed for ShockModeler. This version supports NASA's Guide to Hypersonics and will be used in the high speed inlet simulator.
  3. On 20 Dec 05 version 1.1b was released. This version was developed for the NASA portal and was called Multiple Shock Simulation.
  4. On 22 June 05 version 1.1a was released. This version was developed for the Beginner's Guide to Rockets and moved onto the ESMD server.
  5. In September 03 version 1.0a was developed. This version was created to support the Beginner's Guide to Compressible Flow and solved the expansion fan, crossed shock, and reflected shock problems.

Activities:
Guided Tours

Navigation..


Button to Display Hypersonic Aero Index Button to Display Hi Speed Aero Index Button to Display Aerodynamics Index Button to Display Propulsion Index
NASA's Guide to Hypersonics
Beginner's Guide to Compressible Flow
Beginner's Guide to Aeronautics

 

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Editor: Nancy Hall
NASA Official: Nancy Hall
Last Updated: May 05 2015

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