Strategies for Model Building (or don't try this at home) In a training course we: Cook up problems that are somewhat idealized Build fairly large models all at once Provide detailed instructions, parameter values and l.C.S This optimizes chances for success efficiently uses class time This may not work for you outside of a classroom setting Start small ( 1-4 components). Get that working first Build incrementally: add 1-4 components at a time At each step, carefully consider parameter values and ICS, obtain a valid operating point Crawl Walk Run EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 26
EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 26 In a training course we: Cook up problems that are somewhat idealized Build fairly large models all at once Provide detailed instructions, parameter values and I.C.s This optimizes chances for success, efficiently uses class time This may not work for you outside of a classroom setting Start small (1-4 components). Get that working first. Build incrementally: add 1-4 components at a time. At each step, carefully consider parameter values and I.C.s, obtain a valid operating point. Crawl Walk Run Strategies for Model Building (or don’t try this at home)
Project 1 Build the Schematic for an Air Flow System Model objective: Model a system which takes air from two sources, mixes them together to supply a specified flow of air at a specified temperature Desired Temperature =190F, desired flowrate =30 /b/min =0.5/b/sec Component usage(schematic on next page): Hot airsupply: GD/H- Boundaryconditions for hot airsupply GP/AFP produces pressure disturbance SJHA will be used later to add the pressure disturbance to baseline pressure of 50 psia Valve in VIh regulates flow of hot air GP/HHV GP/SJHV model valve dynamics Connect s_Out SJHA to P1 VH Boundary pressure Connect s out Hhv to oPE vlH Initialize both ops vih and s out IHHv Cold air supply GD/oC- Boundary conditions for cold airsupply GP/AF T produces temperature disturbance SJCA will be used later to add the temperature disturbance to baseline cold temperature Connect s_Out SJCA to TF1 OC Boundary temperature) Flowadder GD/No combines the flows Combinedair flow GD/DP+ GD/PC - Valve in vDP allows regulation of total air flow GP/HOV GP/SJoV model valve dynamics Connect s out IHov to oPE VDP Initialize both ops vdp and s out IHoV Downstream pressure B.C: PP Exit PC Sensordynamics: GD/S and GD/TS measure flowrate and temperature EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 27
EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 27 • Model Objective: Model a system which takes air from two sources, mixes them together to supply a specified flow of air at a specified temperature Desired Temperature = 190 oF , desired Flowrate = 30 lb/min = 0.5 lb/sec • Component usage (schematic on next page): Hot air supply: GD/VIH – Boundary conditions for hot air supply – GP/AFP produces pressure disturbance – SJHA will be used later to add the pressure disturbance to baseline pressure of 50 psia – Valve in VIH regulates flow of hot air – GP/IHHV + GP/SJHV model valve dynamics – Connect S_Out_SJHA to P1_VIH (Boundary pressure). – Connect S_Out_IHHV to OPE_VIH – Initialize both OPS_VIH and S_Out_IHHV Cold air supply: GD/IOC – Boundary conditions for cold air supply Flow adder GD/NO combines the flows Combined air flow: GD/VDP + GD/PC -Valve in VDP allows regulation of total air flow - GP/IHOV + GP/SJOV model valve dynamics - Connect S_Out_IHOV to OPE_VDP - Initialize both OPS_VDP and S_Out_IHOV - Downstream pressure B.C: PP_Exit_PC Sensor dynamics: GD/WS and GD/TS measure flow rate and temperature Project 1 Build the Schematic for an Air Flow System – GP/AFT produces temperature disturbance – SJCA will be used later to add the temperature disturbance to baseline cold temperature – Connect S_Out_SJCA to TF1_IOC (Boundary temperature)
Project 1 Schematic For Air Flow System VIH Valve DynamIcs vary Inpu boundary conditions INab8Poe outlet boundary condition: constant P ADd PresEure Distrognoe HOrse Aod Temperture Dianae c 2 Bache Temperaure CTEC L VDP Valve Dynamics EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 28
EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 28 Project 1 Schematic For Air Flow System vary input boundary conditions lag with limited output outlet boundary condition: constant P set table in IOC component to a size=6
Project 1 Notes on Building the Air Flow Model Add your own qualifiers and edit the component titles so the schematic will agree with the handout You can control the qualifier used from the add menu To move or edit connection labels holdR on connection line, then select Properties or Line Attributes from pop-up menu Set the table size as noted Open the loC Component Data Table-center click on icon Open the table size adjuster- select"Table of 1 var Move slider until“6" appears or type“6 into field Select oK Remember: no data yet Generate the executable Question: Why are we using the IH and SJ combination instead of just a lag component to represent valve actuators? EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 29
EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 29 • Question: Why are we using the IH and SJ combination instead of just a lag component to represent valve actuators? • Add your own qualifiers and edit the component titles so the schematic will agree with the handout You can control the qualifier used from the add menu • Set the table size as noted Open the IOC Component Data Table - center click on icon Open the table size adjuster - Select “Table of 1 var” Move slider until “6” appears or type “6” into field Select OK • Remember: no data yet • Generate the executable Project 1 Notes on Building the Air Flow Model • To move or edit connection labels, Hold-R on connection line, then select Properties or Line Attributes from pop-up menu
Specifying Model Data Numerical data is not part of com piled model Change values without rebuilding model Many analysis options change parameter values during an analysis Vector/matrix and table sizes are part of topology, contents are not Any input may be data user supplied value)or it may be 'connected (computed elsewhere in your model EAS102. December 2005 pyright@ 2005 MSC Software Corporation Chart 30
EAS102, December 2005 Copyright© 2005 MSC.Software Corporation Chart 30 • Numericaldata is not part of compiled model • Change values without rebuilding model • Many analysis options change parameter values during an analysis • Vector/matrix and table sizes are part of topology, contents are not • Any input may be data (user supplied value) or it may be ‘connected’ (computed elsewhere in your model) Specifying Model Data