Manual

VENTSIM USER MANUAL Version 2.45

February 1999 Copyright 1999, CMS SOFTWARE

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CONTENTS 1.0

Disclaimer

2.0

Introduction

3.0

Computer Requirements

4.0

Menu Items

5.0

Toolbar Buttons

6.0

Airway Characteristics

7.0

Building a Ventilation Network

8.0

Using TAG Levels

9.0

Viewing the network

10.0 Printing the network 11.0 Network Simulation 12.0 Tips and Techniques 13.0 Importing and Exporting Data 14.0 Ventsim Version 2 - What’s New ?

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1.0 DISCLAIMER The author and the supplier has no liability to the licensee or any other person or entity for any damage or loss, including special, incidental or consequential damages caused by this product directly or indirectly. The software is supplied "as is" without warranty of any kind, either expressed or implied. Warranties of merchantability or of fitness for any purpose are specifically disclaimed.

VENTSIM Version 2.4 Mine Ventilation Simulation Software Copyright 1999 CMS SOFTWARE

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2.0 INTRODUCTION Ventilation has been a primary concern in mines for hundreds of years, but until the introduction of computerised network analysis in the last 20-30 years, the planning and modeling of ventilation was largely a black art, relying on experience, guesswork and extensive calculations. Even when computer ventilation software allowed simulations of large networks of underground airways, the process of entering and interpreting results still remained a job for experts in the field. WHY USE VENTSIM ? Ventsim provides the user with the tools to . . . •

Simulate and provide a record of flows in an existing mine.

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Perform 'what if' simulations for planned new development.

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Help in Short Term and Long Term planning of ventilation requirements.

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Assist in selection of types of fans for mine ventilation.

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Help in choosing development fans and vent bag sizes.

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Assist in financial analysis of ventilation options.

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Simulate paths and concentrations of smoke, dust, or gas for planning or emergency situations

Ventsim has been written to make the process of ventilation network analysis as easy to use as possible, by utilising a fully graphical mouse driven interface, and running on the universally popular IBM PC under Microsoft Windows 3.1 or Windows 95. Ventsim is designed for easy access for both experienced people and novices to the ventilation process, and allows easy creation, interpretation and manipulation of airway networks.

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3.0 COMPUTER REQUIREMENTS VENTSIM is designed to run under MICROSOFT WINDOWS 3.1 or WINDOWS 95 and requires at minimum the following computer setup. • • • • • • • 3.1

IBM Compatible PC with 386 or 486 or Pentium Processor Optional Maths Co-Processor (387 or 486 DX) Hard Drive 2 Button Mouse Colour VGA or SVGA Graphics Card and Monitor Windows 3.1 4 mb or more Ram

TIPS ON SPEEDING UP VENTSIM To get the most out of Ventsim, a fast 386 or 486 powered computer is recommended to provide adequate speed for the program. The 3D rotation in particular requires a lot of processing power that is best suited to a 486 DX computer or Pentium. Performance increases may be gained by ..... • Maths Coproccessor (a 486 DX or better computer already has one). This will speed up simulation 3 to 5 times. • Graphics Accelerator Card. This will speed up display updates 2-3 times. • Extra Ram. This will increase program slightly, particularly if other applications are being used simultaneously.

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4.0 MENU BAR ITEMS The following pull down menus are available in the Ventsim Main Window. 4.1

File Menu

4.2

Edit Menu

4.3

Airway Menu

4.4

View Menu

4.5

Tag Menu

4.6

Database Menu

4.7

Simulate Menu

4.8

Defaults Menu

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4.1

File Menu

New Erases the network currently in memory. An option is given to save any unsaved changes in the previous network. Ventsim then clears the viewing area, ready for further editing. The previously used RL Database and Fan Database is retained for the new network. Open Allows the user to load a pre-saved network.. Once loaded, the level below the surface RL will be displayed on screen. Merge File Similar to the Open command, but will join two networks together instead of the new one overwriting the old network. This may be useful for joining separate networked areas of the same mine. Caution should be taken however, as duplicate branches are not checked when the networks are merged (duplicate branches will be deleted if an attempt is made to simulate the network). Reload Defaults Reloads the original defaults file that is first loaded when Ventsim is initiated. This may be required, if the defaults loaded with a Ventsim simulation file are incorrect or out of date. Reload Fans Reloads the 'default' fan database that is first loaded when Ventsim is initiated. Although a fan database is loaded with Ventsim simulation files, the default fan database may be more up to date. Once loaded, resaving the simulation file will replace the files original fan database. Save Saves changes made to the network. If the Ventsim title bar shows that the network is untitled, the user will have to select a name before the file can be saved. Save As Saves the network, but gives the option of saving under a different name. Save Defaults Saves the program defaults such as colours, simulation parameters - ie everything found under the Defaults Menu. If Defaults are changed during a program session, and are not saved before exiting, the original loaded defaults will be used again next session. Save Fans Savesa default fan database that is loaded by Ventsim at the start of every program session. If fans are added,. modified or deleted during a program session, and the fan database is not saved before exiting, the original loaded fan database will be used again next session. VENTSIM USER MANUAL

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NOTE: that a fan database is saved with every network file. Save Fans only saves a DEFAULT fan database. This is overwritten when a network file is loaded. Use the RELOAD fan database command to recall the default fan database if it is required. Save Screen Copies the graphical window to a BMP format picture file. This file can then be loaded by a paint package for editing or display. Import Data (CSV) Imports network data from CSV format (text format with fields delimited by commas). This format is widely available through most spreadsheets and can be read into word processors. Minimum data required from a CSV file are the branch node coordinates in the format X1, Y1, Z1, X2, Y2, Z2 although other data can also be imported. See Importing/Exporting section for further information on importing and exporting. Import Data (DXF) Allows the creation or addition to a network of DXF formatted data (supported by most CAD and Mine Planning packages). Note that only a skeleton network (with no additional attribute type data) will be created. The DXF file should contain only the network line strings that will form the network, as anything else will be ignored. Export Data (CSV) Exports the network data in CSV format (Text with field comma delimiters). Note that due to the large number of network attributes, not all are exported. See Importing/Exporting menu for further information on importing and exporting. Export Data (DXF) Exports basic network data in DXF format, for reading by a CAD package. Note that only very limited data is output, consisting of the network branches, names and airflow data. File Comment Allows the user to specify a unique file comment which appears in the top title bar. This comment can help identify the date, name and purpose of the network. Print This command prints the network in the View Window to your Windows installed printer. Note that only printers with Windows supported Graphics Capabilities will be able to print the network (most inkjets and bubblejets, laser printers, some dot matrix). Printing to SCALE is also available, however the scale is initially set to maximum page size. Other options in the Print Dialogue box include Landscape printing and Colour. Again these functions are only supported if your printer has the capability. To change to different printers, use the Windows 'Control Box - Printers'. Note that the default printer should always be set to Portrait Printing before running Ventsim. VENTSIM USER MANUAL

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Previous File List Names of file previously loaded or saved, which may be selected for instant loading of files. Exit This command closes Ventsim. Ventsim will prompt if your network file, fan database or defaults have not been saved since last modified.

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4.2

Edit Menu

Undo Removes any previous addition or deletion to the network immediately prior to selecting this command. Once the network is simulated or re-sorted, Undo can no longer reverse any changes made to the network Copy/Paste This command places Ventsim in the copy/paste mode. Pressing the RIGHT mouse button on an airway copies the specified attributes of that airway (ie size, resistance type, wall type, shock factor) and saves the values as defaults for future airways. Attributes may be specified from the Copy/Paste Attributes menu item. Copied attributes are listed when an airway is copied. All new airways will be drawn with these attributes until changed again. To change an existing airway's attributes with those that have been copied, press the LEFT mouse button on the middle of the airway, or drag a 'FENCE' around multiple airways to be changed. Options The item allows the user to choose which airway attributes are copied and pasted. Ventsim defaults to copying ALL attributes, however this may be changed by selecting/deselecting any of the menu options. For example only airway sizes or wall types may be required to copy and paste onto other airways. Insert Node Allows a branch to be split in two, by clicking the centre of the airway. It is used primarily for joining a new airway into an existing branch, where the existing nodes are not suitably placed. Edit Airway This command loads the Edit Airway Dialogue box, and allows manual editing of each airway. This function is described more fully under the Airway Menu.

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4.3 Airway Menu Add Constructs a new airway. Press the mouse button at the start of the airway, and drag the airway across to the endpoint. Either end of the airway will fix itself to a nearby airway if available, or if no other nodes are in the immediate vicinity, a new node will be created. The airway parameters (size, friction factor, shock loss etc) will be set from the defaults table. Selecting the right mouse button will allow text entry of point coordinates. Note that airways cannot be added in 3D mode unless both end connect to existing branches, or the nodes are entered as coordinates. Move Moves an airway, and any other connected airways - resistances are also recalculated if lengths have been changed. Click on the airway end to move, and drag node to a new location. Use the right mouse button to change the coordinates manually. Note that in 2D mode, dragging an airway with the LEFT button will attach it to a nearby node if one is present, otherwise a new position will be created. In 3D mode, dragging an airway will attach it to a nearby node, or if one is not available, the manual select box will appear. Reverse Reverses the direction of airway flow. The most common use for this command is if a node has no 'from' or 'to' destination when a simulation returns an error. By reversing an airway, you can ensure every node has a 'to' and a 'from' airway. Erase Deletes an airway. To delete individual airways, point to the center of an airway and press the left mouse button. To 'fence' delete multiple areas in a network, drag the mouse across the screen to form a 'delete' box. All airways that have ends or centres inside the delete box will be deleted. Add Fan Adds, changes or removes a fan in an airway. Point to the center of an airway and press the left mouse button. A list of available fans from the fan database is presented. Select the type of fan wanted, enter the number and configuration and press OK. Name Places a descriptive name at the nodes of an airway (end points) or at the center of an airway. The name is purely descriptive, and plays no part in the simulation process. Contaminate Places a contaminant source (gas, smoke or dust) in an airway (a yellow- red symbol is shown), at a specified concentration. One of more of these sources can VENTSIM USER MANUAL

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be added. Using the gas simulation option, the path and concentration of the contaminant will be simulated and shown. The function will only work properly if the network has been previously simulated. Contaminants may be cleared by using 'Clear Contaminant' menu option. Edit Adds, changes or deletes any of the following airway characteristics via a dialogue box. Select an airway centre with the LEFT mouse button to edit the airway. 1. 2. 3. 4. 5. 6. 7.

Resistances - fixed or from pick list Wall Types Shock Factors Branch Names Fixed Flows, Lengths Airway types - ie shaft or drive Airway dimensions

Note that by pressing the Right mouse button instead of the Left button on an airway, the top resistance from the pick list will be added or removed. Info Shows basic information about airways (size, quantity, pressure drop, pressure load, length, coordinates). If a fan is present, it shows the fan curve, operating point and working pressure. If a FIX is present, it shows the required pressure, and/or regulator resistance for the Fixed quantity. Fix All Lengths This will fix and protect all airways in the network from changes in length when moving airways. This is useful if airways are required to be moved for clarity, but lengths must stay the same. Unfix All Lengths This will unfix and recalculate all airway lengths in a network. WARNING - This function will change any previously fixed lengths. If there are any doubts, use the EDIT function to individually fix/unfix lengths of only the airways that need to be changed. Clear Contaminant Clears all contaminant sources, and also clears any simulated smoke trails in a network.

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4.4 View Menu Zoom Zoom allows enlarging, reducing or panning of the screen view port. Use the left mouse button to zoom in (ie. reduce the scale), either by drawing a box or by clicking the button once. To ZOOM out (or increase the scale) click the right mouse button on the screen. To PAN about the screen, again use the RIGHT mouse button, but hold the button down, and move the mouse about the screen. The screen will follow the mouse pointer. Note that the ZOOM magnification factor and Printer Scale is shown in the bottom left corner of the Ventsim screen. Grid Displays a coordinate grid to help in viewing and locating airways. The grid is 'passive' and is simply an overlay on the screen, playing no further part in constructing networks. The mouse coordinates are shown in the lower left of the screen. Grid scales can be adjusted by altering the simulation defaults - found in the Defaults Menu. Note that the GRID cannot be displayed when in 3D mode. Fit Rescales the screen so that all airway branches on the current RL are displayed on the screen. Find Allows the user to automatically locate parts of a network. Selecting one of the options will find and zoom into the area desired. The option may be repeated for further branches by pressing the FIND Toolbar button. Options include: •

Branch Error : Finds branches with simulation errors

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Stalled/Negated Fans : Finds fans operating in network outside fan curve

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Branch Number : Finds the specified branch number

•

Branch Name : Finds all branches with all or part of the specified branch name.

•

Branch Node : Finds all branches with all or part of the specified node name.

Plan View The standard horizontal plane viewing mode.

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3D View Displays a three dimensional representation of the network. This view defaults to a plan view, with standard isometric, long sections and horizontal sections also available from the view pull down menu. The view may be rotated in any direction with the rotation button. Levels Single Displays a single level of data Multiple Allows the user to choose up to six non consecutive levels to display. Range Allows the user to display all levels between two selected levels All Levels Displays all levels in the RL database simultaneously on screen. Data Type Display a variety of different kinds of data. See the data type menu for a more detailed description of these. Display Options Allow the user to turn on or off parts of the graphical display. This is usually done to improve the clarity of display, and show only the parts of the network that are required to be viewed. Note that turning off all options (or by using the HIDE function), results in a 'skeleton' display. The display update speed in this case is dramatically improved. This is useful if viewing or searching through large amounts of data.

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4.5 Tag Menu Tag levels allow the user to place groups of airways on different levels, so that they may be displayed independently of all other airways. •

Primary Tag Levels are intended to group TYPES of airways together (eg Shafts, Declines, Stopes, Raises etc).

•

Secondary Tag Levels are intended to group an area a network together (eg Shaft system, orepass system, stope system, workshop area).

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Primary and secondary tag levels can be used independently of one another.

Primary Displays all primary tag levels and names. If the checkbox is highlighted, then all airways on the highlighted level will be displayed (providing the secondary tags are also set). The 'active' tag level will be displayed in either blue or red. To make any level active, simply click on the level once with the mouse. Primary tag levels range from 1 to 16. Secondary Displays all secondary tag levels. The use of the secondary tag checkboxes, is the same as the primary tags as stated above. Secondary tag levels range from 1 to 48 Options Tag display options will give the user the opportunity to change the way Ventsim displays tag levels that are 'turned off' or 'hidden'. The default display will be to hide all off-tag level airways, however these can be displayed as dim grey lines, or full lines. The amount of data (eg names, flows, arrows etc) showed for off-tag level airways can also be modified. Show All Turns on ALL tag levels (both Primary and Secondary) so that every airway in a network will be displayed. Hide All Turns off ALL tag levels (both Primary and Secondary) EXCEPT the active primary and secondary tag levels which will be turned on.

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4.6 Database Menu Fans Displays a dialogue window which allows editing, adding and deleting of all fans in your fan database. Up to 1000 fans and their curves may be entered into the fan database. A display of each fan curve will be presented upon clicking on the fan name in the display list. Further fans can be added by selecting blank spaces, or by overwriting existing fans. Caution should be taken when deleting or modifying a fan, as any network which may have used that fan number, will still attempt to use that particular number fan's data. If the data is not present, or is different, the network will not simulate properly. Levels Displays a dialogue window which allows editing or creating of the RL Database a database which contains up to 250 RL levels on which your network will be created. RL Data can be edited in any order, as well as added at a later date - Ventsim will sort the data from highest to lowest when next displayed. Airways This will display a list of currently entered airways in a spreadsheet form. Data cannot be changed, but searches can be made in network data that can narrow down to airways with FANS, FIXES or ERRORS. This can be useful for finding airways that may be restricting network analysis, or causing other problems (eg stalled fans, airways with errors etc).

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4.7 Simulate Menu Airflows This will perform a network analysis air simulation, and attempt to come up with a solution to your network. If the simulation is successful, the simulation dialogue box will disappear and the screen updated to show new airflows. If the simulation is not successful, a list of errors will be shown. Note that the tool bar button 'AIR' will perform the same function as this. Contaminant (GAS) Performs a contaminant simulation based on the position of contaminant sources previously placed in the network (see AIRWAY menu for placing contaminant sources). Contaminants should be cleared before any further editing is done to the network. The contaminants may be cleared by pressing the CLEAR button on the smoke legend, or by selecting CLEAR CONTAMINANTS from the AIRWAY MENU. Note that the tool bar button 'GAS' will perform the same function as this, but will automatically bypass the input box. Summary Displays a brief summary of your network. Note that some values in this summary are only valid for a fully working, balanced network.

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4.8 Defaults Menu Options from this menu can change the appearance and operation of Ventsim. Display Colour Allows changing of the colour scheme of the network on screen and printer. Upon viewing the Colour Dialogue Box, simply select the colour to change on the left side of the box, and then select a new colour from the list on the right side. Beware when changing some of the colours if a colour printer is being used. The new colours may not show up well on the printer. Graphics Allows changing the various aspects of the way your network is drawn on the screen, including Line Thickness, Text Size, Arrow Size and Node Size. Any general increasing of the size or thickness of any of these, while improving clarity, can greatly decrease the speed of graphic screen updates - particularly increased Line Thickness. Grid Allows the changing of several parameters including: •

Grid Spacing - allows variable grid line intervals (eg 10m, 50m, 100m etc).

•

Node Spacing - restricts placing of nodes to a minimum spacing. For example if you want a node to be placed only on 10m grid interval (ie 4010, 4020 etc) then this can be set to ten. By doing this it is also easier to place exact vertical and horizontal airways.

3D Rotation Allows changing the rotation speed, and tilt limitations of the network models. Rotation jump steps are in degrees. Program Simulation Allows changing of various simulation parameters including maximum allowable errors, number of iterations etc. Changing of these parameters may improve the speed of simulation of your network, but can also decrease the accuracy of results. Airway Allows changing of default airway sizes and attributes, so that new airways drawn also have these same attributes. Note that COPY ATTRIBUTES from the EDIT menu does the same thing. VENTSIM USER MANUAL

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Calculation Allows changing or adding of the parameter definitions of Resistances, Wall Types and Shock Types, as well as their displayed names. WARNING - these values should only be changed if the function of these values is understood, and new values have measured or demonstrated accuracy. Changing of these values will also alter the attributes of every branch in a network that uses these values. New resistances can be added by selecting the 'undefined' values, and typing in new names and values. Mouse Control Mouse Node Sensitivity - reduces or increasing the tendency for the mouse to grab the nearest node when placing or deleting airways. This is handy as accurate mouse placement is not normally required, but can be frustrating if nodes need to be placed close to one another, without having to zoom in. Lower Values increase the tendency for the mouse to grab nearby points.

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5.0 TOOLBAR BUTTONS Toolbar buttons provide almost all the functions needed to create and analyse a airway network Rotate Button The large button at the right of the tool bar is the network rotation button. Clicking on any of the arrows on the button will rotate your network in that direction.. Two speeds of rotation are available by moving the mouse pointer further to the edge of the button. The small button at the centre is the 'rotation centre' button. By clicking on this button, and then selecting the middle of an airway on screen, the model will then be rotated about this branch. To reset the rotation centre to the centroid of the model, simply choose 'rotation centre' and click on a blank part of the screen. Note that the model can be rotated continuously for display purposes by simply using the RIGHT mouse button instead of the left to rotate the model.

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5.1 Bottom Toolbar Functions Blue Buttons - View Manipulation Zoom Button Allows enlarging and reducing of screen view port. Use the left mouse button to zoom in, either by drawing a box or by clicking the button once. To ZOOM out click the right mouse button. Fit Button Fits all graphic airways on the current display level into the view port. Redraw Button Redraws the screen in the event that the screen is partially erased by another screen or program Find Button Finds a selection of different types of airways as specified in the Find menu. Repeated pressing of the button will find the next occurrence of the specified type.

BLACK - Editing Functions Add Button Constructs an airway. Press the mouse button at the start of the airway, and drag the airway across to the endpoint. Either end of the airway will fix itself to a nearby airway if available, or will create a new start/end node for the airway. The airway parameters (size, friction factor, shock loss etc) will be set from the defaults table. Note that by pressing the RIGHT mouse button, a coordinate window will be displayed, allowing the user to manually enter the coordinates. Note that if manual coordinate entry is required for just the end point, then while 'rubber banding' with the LEFT button, select the RIGHT mouse button simultaneously. Copy / Paste Button Allows the user to copy an airway's attributes (dimensions, shock type, wall type) and paste them onto other airways. The RIGHT mouse button will copy the attributes into the defaults. The LEFT mouse button will paste them onto another airway, by pressing the middle of the airway. Multiple airways can be changed by 'fencing' an area with the LEFT mouse button. All airways with ends within the fence will be changed to the copied default values. Note that you should make sure that only the attributes you desire to copy are first selected from the copy/paste attributes menu on the EDIT menu bar, otherwise unwanted attributes may be pasted onto your airways. Move Button VENTSIM USER MANUAL

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Moves one end of an airway, and any other connected airways. It will also recalculate resistances if lengths of airways have been changed. Click on the airway end to move, and drag to the new location. The new location can also be manually entered by coordinates by pressing the RIGHT mouse button. This is particularly useful if the RL of the airway is required to be changed within the level. Large areas of airways can be moved by 'fencing' an area with the LEFT mouse button. The 'manual coordinate' window will display and allow the user to enter the displacement for the move area. WARNING - using ' fence move' will only move displayed airways within the fence. If airways are hidden with the TAG function or are not shown in the current RL range, then airways connecting to them will not be moved. This may cause nodes to have the ends moved away from hidden airways, resulting 'no exit/entry' errors on simulation. Flip Button Reverse direction of an airway flow - This is normally used to ensure all nodes have an entry and exit. Note that airways will automatically correct their direction if the airflow is reversed during the simulation. Erase Button Deletes an airway. To use, point the mouse to the center of an airway and press left mouse button. Make sure no other connecting airways exist before simulation, as a destination error will occur when simulating.

PURPLE - Airway Property Functions Fan Button Adds or changes a fan in an airway. Point to the center of an airway and press the Left Mouse Button. A drop down menu box will allow a selection of fan types, while other options on the form will allow changing of the number and a parallel or series setup. Name Button Places a name at the nodes of an airway (end points) or at the center of an airway. Names are entirely for user reference and do not affect simulation. Note that there are only a limited number of characters available for a name. Contaminant Button Places a Contaminant Source and concentration along an airway (a yellow/red mark is placed on airway). One of more of these sources can be added. Using the toolbar button, the path and concentration of the VENTSIM USER MANUAL

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contaminant is shown. This function can only be used providing the network has been previously simulated. Contaminants may be cleared by using 'Clear Contaminant' menu option. Pressing the RIGHT mouse button will automatically place a 100 strength contaminant if none is present, and will automatically remove a contaminant if one is present.

GREEN - Airway Information Edit Button Brings up an Airway Edit form when mouse is clicked on an airway, which allows fine tuning and changes of airway sizes, type and parameters. Info Button Shows basic information about airways (size, quantity, pressure drop). If a fan is present, it shows the fan curve and operating point. If a FIX is present, it shows required pressure (Pa) and resistance for the FIX.

RED - Simulation Functions AIR Simulation Button Simulates the air flows and pressure drops in a network. If any error exists, it will list the branches with errors. Graphically, the errors are shown as BOLD airways, with the name ERROR.

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5.2 TOP TOOLBAR FUNCTIONS Save Button Saves the network immediately under the current name. Load Button Opens the LOAD dialogue window to load another Ventsim network Print Button Prints the current screen contents on the windows attached printer Grid Button Displays/removes the coordinate grid in 2D mode. Note that no grid is available in 3D mode. Multi Level Button Toggles between single RL Level display and Multiple RL Level display. The multiple RL display will be the previously selected Levels, whether they be Selected, Ranged or All. 3D Button Toggles between 3D mode and 2D mode. Only limited editing is available in 3D mode. The button will remain pressed down while in 3D mode. Saved View Pull Down List Recalls a list of previously saved views. View names are presented in alphabetical order. The first 5 views are permanent orientations and cannot be saved or changed. These views are also special in that they will only orientate existing data on screen, not recalling any position, zoom magnification and tag levels that other saved views will. To save extra views, simply go to the VIEW Save menu item and enter the name of the view. Up to 100 saved views may be stored. View Options Button Shows the view options window, which allows the choice of displaying various levels of data and information. Useful for uncluttering the display for easier viewing. Tag Button Converts existing airways to the active Tag level, whether it be Primary or Secondary. To set the active level, view the Primary or Secondary Level window from the TAG menu, and click on the level (so it turns red). Pressing the LEFT mouse button on the center of an airway, will change it to the active tag level. To change multiple airways, draw a 'fence' with the LEFT mouse button. All airways with ends or centers within the fence will be changed to the active tag level.

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If the active level is turned off, then airways that are tagged will 'disappear' from the view. This is useful to ensure that all airways required to be tagged have been tagged. GAS Sim Button This button activates the contaminant simulation, and immediately moves into the simulation process and displays the result. If simulation input is required (eg a change from fixed to cumulative simulation) then menu item CONTAMINANT SIMULATION from the RUN menu should be chosen instead.

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6.0 AIRWAY CHARACTERISTICS An important part in the modeling and simulation of a ventilation network, is accurately setting the characteristics or parameters of an airway. When airways are initially constructed, the airway characteristics will be set to a series of defaults. Any of the following parameters can be changed by selecting the EDIT button, and clicking on the airway. Square or Circular Airway Square and Circular airways are assumed automatically to be horizontal and vertical airways respectively, when initially constructing airways. If this is not true (for example, a vertical airway is a actually a long hole winze measuring 2.0m by 2.0m), then the type of airway should be changed to square to reflect the shape. Airway Dimensions (m) Airway dimensions are entered as Height & Width (in metres) for a square airway, and Diameter (in metres) for a circular airway. Ventsim calculates the crosssectional area from these values, for use in the simulation. If an airway shape does not match either square of circular shapes (eg heavily shantied back) then values should be entered that give equivalent areas. Fresh or Exhaust Air Types Ventsim allows the user to choose whether an airways will be displayed as Fresh, Exhaust or unspecified air. Note that this function is only to assist the user in recording and showing air types, and plays no part in Ventsim calculations. All new airways will be unspecified until set as fresh or exhaust air. Air types must be set manually for each airway, however the copy/paste function can be used to copy an existing fresh/exhaust air condition, and (fence) pasting the air type over other airways (note all other copy/paste attributes should be deselected when doing this). Fresh/exhaust airways colours will only be shown if the 'Fresh/Exhaust air' display option is selected under the Display Options menu or the Defaults Colours menu. Show Data Ventsim will only show data of airways with this box selected. If not selected, a line will simply represent where the airway is on screen. No arrows, nodes, fans, bulkheads or written data will be shown on the airway. This function can be used to 'unclutter' a display, by just showing the important airways. Surface Entry and Exit Selecting either of these will force the airway node to the surface, without actually require the node to be placed there. This is useful for placing fixed air into or from a network without a vertical branch to the surface, or when the surface is a changing RL (eg the mine located on a mountain side) and airways are required to enter or exit the mine at any RL.

VENTSIM USER MANUAL

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Length (m) Length is calculated automatically when entering airways. If the automatically calculated length is not the true length (for example, a spiralling decline is drawn as a vertical line between levels, but is obviously longer than the vertical line), then the length should be set to FIXED, and the true length entered. Note that a FIXED Length will not change if the airway nodes are moved. Resistance (Ns2/m8) Resistance is calculated automatically when entering airways from its size, type, length and several other factors. If the airway has no obstacles, then this does not have to be calculated. Airway obstacles such as doors, bulkheads, muck piles etc, exhibit a resistance usually much greater than the airway itself. Some obstacle resistance values are included in the defaults. Up to 50 resistances can be added or changed from the DEFAULTS - Airway Parameters menu. If the resistance is known to be a different value (for example, it has been calculated in a ventilation survey), then the resistance can also be fixed, and the true value type in. Note that a Fixed or Obstacle resistance will not change if the airway is moved or lengthened. Friction Factor (k) Atkinsons friction factor describes the roughness or uneveness of wall. Uneven walls create turbulent airflow along their boundary, thereby increasing the resistance of an airway. A range of common values are suggested in the defaults, but other values may be entered with the USER DEFINED option from the menu list. Shock Loss (m) Shock Loss is a term used to describe the turbulence caused by sudden changes in airflow direction or flow shape. Examples are a sharp corner, or sudden change in drive size. Ventsim uses extra metres for a shock loss values - for example an airway with a medium shock loss may suffer an increase in resistance equivalent to an extra 50m long stretch of the airway. Ventsim comes with a series of Shock Loss defaults, describing different sized shock losses. Use the following as a guide, but feel free to change to your own definitions. ( Note that the airway receiving the airflow is the one upon which the shock loss should be applied.) • • •

Airways that join into one another in a straight line have no shock loss Airways that join into others through a corner 90 and