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.
Recently (2013), there have been several security patches added to the Java Runtime Environment (JRE). As a result of the security patches, EngineSim does not always perform as it did in the past. Since you have downloaded this version of the program, you may experience some of these problems. One patch does not allow the display of .gif images from a local directory. So you will not be able to see the engine animations in Tunnel Test Mode or any of the component pictures on the output panel at the lower right which were available on earlier versions. We have maintained all the functionality of previous versions, but just do not display any photos.
This program is designed to be interactive, so you have to work with the program.
There are several different types of widgets that you use to work with the program.
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 four main parts:
ENGINE DESIGN PROCESS:
You can choose from four different types of engines: a simple turbojet, a jet with afterburner, a turbofan engine, or a ramjet. Selections are made on the graphics window by clicking on the engine name. The chosen engine is shown in yellow. Depending on the engine type, different input panels appear at the lower left.
The design process begins by selecting the design Flight Conditions. The Flight input panel lets you change the Mach number, airspeed, altitude, pressure, temperature, and throttle and afterburner settings. There are several different combinations of these variables available for input using the choice button on the input panel. The pressure and temperature are computed as functions of the altitude by using a Standard Day atmospheric model.
Design variables for each engine component can also be varied. The variables include the Inlet (pressure recovery), Fan (pressure ratio, efficiency, and bypass ratio), Compressor (CPR, compressor efficiency), Burner (fuel,maximum temperature, efficiency, pressure ratio), Turbine (turbine efficiency) and Nozzle (maximum temperature, efficiency, A8/A2). As you choose a different component the part of the engine being affected is highlighted in the graphic by changing from its default color to yellow. And a new input panel will appear at the lower left. If you change the Output Display to Photos you can view an actual photograph and description of each engine part.
Engine Size can be specified by either the frontal area or the diameter. As the engine size changes, the grid background changes in proportion to the size. The distance between any two grid lines is 1 foot.
MATERIALS INPUT
The program will calculate an average weight of the engine that you design. The thrust to weight ratio of the engine is displayed in the numerical output and is a measure of the efficiency of the engine. The weight depends on the number of stages in the compressor and turbine, the diameter (frontal area) of the engine, and the component materials. The program begins with standard materials for the components, but you can change the materials and see the effects on weight of the engine. Just push the blue Materials choice button on any component input panel. You can also select to define your own material by choosing My Material from the menu. Just type in your own values for material density and temperature limit.
The program will check the temperature throughout the engine design against the material limits. If you exceed a limit, a flashing warning will occur in the schematic. You can see the temperature limits by choosing Graphs in the Output display of the control panel. Then select Temperature as the type of graphics display. (For the afterburner and the ramjet, the graphical temperature limits are based on the flow temperature, not on the material temperature, and are slightly higher than the material limits. Cooling airflow is often used along the walls of these components to keep the material temperature within limits.)
CONTROL PANEL CHOICES: Mode, Units, Output Display
The program works in two modes: Design or Tunnel Test Mode. In the Design Mode, you can change design variables including the flight conditions, the engine size, the inlet performance, the turbo machinery compressor and turbine performance, the combustors or burner performance, or the nozzle performance. For a turbofan engine design you can also vary the fan performance and the bypass ratio. In Design Mode, any change in an input parameter produces a new engine design. You have to be very careful when drawing conclusions about the effects of input variables on performance because you are not comparing the effects on the same engine.
In Tunnel Test Mode you can vary only the flight conditions and you can not change any of the component design parameters except the throttle setting. The values of some of the parameters like inlet recovery and nozzle area may change according to choices that you made during design. In Tunnel Test Mode you are evaluating the off-design performance of the engine model which you specified in Design Mode. In Tunnel Test mode, you can load models of existing turbine engines for comparison with your design. You can always reload your design to continue testing. In Design Mode, you can use the existing engine models as good starting points for your design.
The calculations can be performed in either Metric or Imperial (English) units. You can always return to the default conditions by pushing the red Reset button on the control panel.
GRAPHICAL OUTPUT
The red Output display menu on the upper right control panel allows you to change the contents of the output window on the lower right side of the screen. You can choose to display output boxes with numerical values of the engine performance, as described below. Or you can display photographs and descriptions of each engine part. Or you can plot the variation of the value of pressure and temperature at various stations through the engine. Or you can also display a T-s Plot or a P-v Plot, which are used by engineers to determine engine performance.
To generate your own performance plots, select "Generate" from the graphics window. The input panel will now display some additional buttons and sliders to generate a plot. Choose the variables to be plotted using the pulldown menus and then push the "Begin" data button. Set the value of the independent variable by using the slider or the type-in box. Push the blue "Take Data" button and a data point will appear on the graph. Set a new value for the variable and take another data point (up to 25 points in any order). When you are finished, push the "End" button and a line will be drawn through your data points. To start a new graph, push "Begin" and your old graph will vanish. When you are finished, push the red "Exit" button and you will return to free stream conditions.
NUMERICAL OUTPUT
Numerical Output from the program is displayed on two panels. The total engine performance is always displayed on the control panel panel at the upper right and includes the engine net thrust, the fuel flow rate, the engine air flow rate, the engine weight, the thrust to weight ratio, and the specific fuel consumption.
There are two additional performance panels that are displayed atthe lower right. The Engine Performance output panel shows the fuel-to-air ratio, the engine pressure ratio (EPR)and engine temperature ratio (ETR), gross thrust, and ram drag. Additional component performance parameters, such as the nozzle pressure ratio (NPR), compressor pressure ratio (CPR), engine thermal efficiency, nozzle exit velocity (V exit), free stream dynamic pressure (q0), and specific impulse (ISP) are displayed. Nozzle exit pressure (Pexit) and fan nozzle exit pressure (P fan exit) and the compressor face Mach number (M2) are also displayed. The Component Performance output panel shows the variation of total pressure and temperature at various stages through the engine.
NEW FEATURES
The NASA Glenn Educational Programs Office will continue to improve and update EngineSim based on user input. Changes from previous versions of the program include:
INTRODUCTORY EXERCISE
Set the following conditions in EngineSim:
Design Mode
English Units
Turbojet
Flight Conditions
The Airspeed
should be 0, the Altitude 0, and the Throttle 100. Record the thrust
(F net) ___________and the Fuel Flow __________.
Now go ahead and change the altitude to 10,000 ft. and the Airspeed to 350.
Did the thrust increase or decrease? Did the fuel flow increase or decrease?
Thrust ________ Fuel Flow__.
What happens when you choose a different engine? Choose a jet with afterburner
and record the thrust ___________ and the fuel flow ____________.
Choose a turbofan engine and record the thrust _____________ and the fuel
flow________.
What can you conclude about the effect of an increase in altitude and airspeed
on thrust? __________________________________ On fuel flow?__________________________
Which engine is most fuel efficient? _______________________________
Last Updated
by Tom Benson