ONX User Guide

8/6/2019 ONX User Guide

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ONX Program

User Guide

Version 5.111

April 8, 2004

Copyright 2002 - 2004 - Jack D Mattingly, Ph.D.


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Table of Contents

1.Main Window 32.View Data Window 43.Results Window Multiple Calculations 54.Results Window Single Point Calculation 65.Plot Window Multiple Calculations 86.Carpet Plot 117.Mollier Plot Window Single Point Calculation 148.Optimum 14

Copyright 2002 - 2004 by Jack D Mattingly, Ph.D. No part of this publication may be

reproduced, distributed, or transmitted, in any form or by any means, or stored in a

database or retrieval system, without the prior written permission of the copyright

owner.

Hint for Data Editing: This program uses edit fields foruser editing of each piece of data. The program waits until

you enter the tab or enter key to accept your data entry in

that field. Use the tab key to move between data edit fields.


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1. MAIN WindowWhen the ONX program is run, the default input data file (onx.onx) is read and the Main window is displayed

as shown below.

The parametric (on-design) cycle analysis program ONX is based on the equations developed inAircraft Engine

Design, Second Edition, and can analyze the following seven different engine cycles:1. Turbojet without afterburner single spool.

2. Turbojet without afterburner dual spool.

3. Turbojet with afterburner dual spool.

4. Turbofan with separate exhausts (convergent-only exhaust nozzles) dual spool.

5. Turbofan with mixed exhaust and no afterburning dual spool.6. Turbofan with mixed exhaust and afterburning dual spool.

7. Turboprop (convergent-only exhaust nozzle) dual spool.

Each of these cycles can be analyzed using the user-selected unit system (English or SI) and ideal (perfect) gasmodel (three choices: CSH, MSH, or VSH).

This program is designed to be user-friendly and multiple windows are used for program control and data input.

Parametric (on-design) input data files may be saved on disk for later use (the file extension onx is used for these

files). Also, saved parametric (on-design) input data files may be read from disk for current use. Multiple

calculations for different values of one design variable are possible by selecting the iteration variable from theIteration Variable menu and then specifying its minimum, maximum, and incremental values. When single point

calculation is selected, the Mass Flow Rate window (see below) opens for user input of this design value. Program

output is directed to an output window and may be sent to a printer. The carpet plot feature allows rapid generation

of carpet plot figures similar to Figs. 4.E2 and 4.E3 inAircraft Engine Design, Second Edition.


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2. VIEW DATA Windows

Pressing the View Data button on the Main window opens an input data window for the selected engine cycle

and gas model similar to that shown below.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

NOTE When the user presses the Perform Calculationsbutton, they will be asked if they want to save the input

data before the calculations are performed using the following window. The user can check the box and turn off this

reminder.


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3. RESULTS Window Multiple Calculations

Pressing the Perform Calculations button on the Main window causes the Results window to be opened and

the input data and results displayed as shown below. The results for each value of the iteration variable are saved for

later plotting.

After one set of multiple calculations has been performed, the Plot Results button on the Main window

becomes active and the number of plot lines listed as shown below. The results of the multiple calculations can beplotted using the included Olectra Chart software (press Plot Results button on Main window) or can be saved to anexternal file by pressing the Save button (see above) on the Results window. The results saved in the external file

are separated by commas and can be easily copied and pasted into a program like Microsoft Excel (To separate the

data, use the Text to Columns item in the Data pull-down menu and indicate that the data is comma delimited).


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4. RESULTS Window Single Point Calculation

Pressing the Perform Calculations button on the Main window causes the Results window to be opened and

the input data and results displayed as shown below. The results for this single point calculation are saved for later

plotting.

When the Done button is pressed, the user is asked if they want to save the reference data that has been

calculated for this engine for input into the AEDsys program as shown below. Replying Yes opens the Save As filedialog box shown on the next page.


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Note: The reference data file required for input to the performance (off-design) cycle analysis program portion

(Engine Test) of the AEDsys program can only be generated by performing a single design point calculation

and then saving the required output data to a user-named reference data file (the file extension ref is used for

these files) as shown above.

After the single point calculation has been performed, the Plot Single Point on Mollier Chart button on theMain window becomes active as shown below.

Press the Engine Station #s button on the Main window to display a sketch of the engine showing engine

station numbers as shown below.


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5. PLOT Window Multiple Calculations

Pressing the Plot Results button on the Main window opens the Plot window as shown below for user selection.

This particular result was from calculations of the turbofan engine with mixed exhaust, modified specific heat

(MSH) model, and fan pressure ratio (Pif = -1, selected by program to match total pressures entering the mixer).Calculations were performed over the range of bypass ratios from 0.3 to 0.5 for four different compressor pressure

ratios (Pic = 24, 20, 16, and 12).

Pressing the Plot button gives.


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Lets mark the maximum allowable thrust specific fuel consumption (S) on this plot at 1.1 (Y Marker) and a

maximum value of the bypass ratio at 0.4 (X Marker). This is done on the Plot Variable window by check the box

for X Marker, enter the X Marker value 0.4, check the box for the Y Marker, and enter the Y Marker value of 1.1.First, right mouse click on the plot. In addition, the labels and legend of the plot can be changed using the edit

features on the Plot Variables window. First uncheck the Automatically Label Lines box. Above the Remove Lineof Data and Replace Line Label buttons is an edit window. Selecting a line label from the list will place that linelabel in the edit window. The user can edit the label and press the Replace Line Label button to replace the old

label for that line. This was done for the four lines of data from the previous page to get the result shown below. In

addition, the legend label was replaced by entering a new legend name into the edit box and pressing the ReplaceLegend button giving these results.

Pressing the Plot button gives the plot with new labels, legend, and markers.


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The Olectra Chart plotting package allows the user to customize each plot using the chart control propertieswindow. Clicking the right mouse button over the plot will open the 2D Chart Control Properties window as

shown below. For example the minimum and maximum of the X axis can be changed by selecting Axes, then selectScale, enter the value for the X axis, and then press Apply followed by OK.


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6. Carpet Plot

Carpet plots similar to Figs. 4.E2 and 4.E3 in Aircraft Engine Design, Second Edition can be generated by

selecting the Carpet Plot radio button on the ONX main window as shown below.

Pressing the Carpet Plot radio button opens the Carpet Plot Data window, shown below. Compressor pressure

ratio and bypass ratio are selected as the two variables with the corresponding data values entered. Press the

Calculate button to performs all the necessary calculations and when complete the Plot button becomes active.


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At the completion of the calculations, the Carpet Plot Data window will appear as shown below with the Plot

button active and the number of plot lines shown.

Pressing the Plot button opens the Plot Variable windows as shown below. After unchecking the AutomaticLabel Lines check box and editing line labels, the following is displayed. The user can add X and Y Markers to the

plot using this window. Pressing the Plot button generates the carpet shown on the next page.


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7. MOLLIER PLOT Window Single Point Calculation

After the single point calculation has been performed, press the Plot Single Point on Mollier Chart button on

the Main window to generate a plot similar to that shown below.

8. OPTIMUM

The user can specify that the program determine optimum values of specific design variables by entering a 1into that variables data field. The following engine cycles and corresponding optimum are available:

Engine Cycle Variable Description

High Bypass Turbofan Bypass Ratio Minimum thrust specific fuel consumption

Bypass RatioMixed Flow Turbofan

With/Without AB Fan Pressure Ratio

Matched total pressures entering mixer

Turboprop Turbine Enthalpy Ratio Minimum thrust specific fuel consumption

Documents

ONX User Guide