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ShockSim Version 1.3e

Glenn
Research
Center

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.

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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:

Button to Download a Copy of the Program

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:

  1. At the left of the screen is a graphic of the wedge or cone and shock waves that you are studying.
  2. On the upper right 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

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:

  1. 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.

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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