General Data Variables

Tol1:

Maximum acceptable flow error in any non-boundary chamber for the model to be considered 'converged' where flow error in chamber 'j' is defined by the equation:

This is mass balance as a percentage of the average through flow. By default , TOL1 is the primary flow error tolerance variable.

(Default TOL1 = 1%) But should be reduced as far as possible (0.1% or 0.01% are good).

Tol3:

Maximum acceptable flow error in any non-boundary chamber for the model to be considered 'converged' where flow error in chamber 'j' is defined by the equation

Error1 can be the most severe since the Error can be large if the chamber thru-flow is very low even if the imbalance is low in terms of lbm/sec. TOL3 can be used if you model has convergence problems using Error1.

Tol2:

Maximum acceptable flow error in any non-boundary chamber for the model to be considered 'converged' with flow error in chamber 'j' based on the following equation:

This is mass balance as a percentage of the total flow into and out of all boundary chambers. By default, TOL2 is the secondary flow error tolerance variable.

Since ERROR2 is based on the boundary flows rather than the local chamber, TOL2 should be more easily satisfied than the same value of TOL1.

In those cases where some chambers have small flows, which are possibly unimportant to the user, TOL2 is a useful means of solving a model to within acceptable engineering accuracy.

(Default value = 1000.)

TOL2 may also be used as an alternative to TOL1 when the variable TOL2_CHAM is set. The use of TOL2 in this option is explained in the TOL2_CHAM description.

Tol4:

Maximum acceptable flow error in any non-boundary chamber for the model to be considered 'converged' where flow error in chamber 'j' is defined by the equation

The Reference flow rate for Error4 is set in the Analysis Setup → Reference Conditions → Reference Flow Rate (lbm/sec)

User can use the option they feel gives them accurate results and good run time.

Flag that activates the alternative use of the convergence input variable TOL2.

The purpose of this variable is to allow declaration of convergence of models that, based on TOL1, would converge except for local chambers that are extremely slow (or impossible) to converge but are in areas of the model not critical to the analysis or in low flow areas where large percentage mass discontinuities are not critical.

The approach for its use is to select a chamber that is normally slow to converge, as judged by ERROR1, but is not in the “trouble” zone. The idea being that when the selected chamber meets convergence tolerance, all the important chambers are converged. The selection of an appropriate chamber can be tricky so this option should be used with care.

TOL2 is then input as a value substantially smaller than TOL1 and TOL2_CHAM is set to plus or minus AAAA.BBB where AAAA is the number of the selected reference chamber and BBB is the iteration after which the model will be allowed to declare convergence if ERROR1 in the reference chamber is less than TOL2. This declaration of convergence will be independent of convergence in all other chambers. Convergence would also be declared if all chambers meet TOL1 tolerance with their ERROR1 values.

With positive values of TOL2_CHAM, convergence can only be declared if all cavities (if any) have converged. Negative values serve as a flag that declaration of convergence is independent of cavities.

(Default value = 0000.000 means that the TOL2_CHAM criteria is not used)

Damping factor for the iteration-by-iteration adjustment of the calculated change in static pressure at each internal chamber.

Inversion of the FlowSimulator solution matrix at each iteration step yields the Newton-Raphson step sizes for each chamber static pressure. DAMPS is used as a scale factor, which is often less than one, and thus provides a more conservative step towards the solution than standard Newton-Raphson method. This improves robustness and convergence properties in the face of the non-linear and discontinuous behavior of the flow equations.

The optimum values for DAMPS and DAMPT are model dependent. Values between 0.3 and 1.0 are commonly used. Values greater than one are used when the maximum errors become progressively smaller on successive iteration steps.

(Default value = 0.4)

Damping factor for the iteration-by-iteration adjustment of the calculated change in total pressure at each internal chamber.

Inversion of the FlowSimulator solution matrix at each iteration step yields the Newton-Raphson step sizes for each chamber total pressure. DAMPT is used as a scale factor, which is often less than one, and thus provides a more conservative step towards the solution than standard Newton-Raphson method. This improves robustness and convergence properties in the face of the non-linear and discontinuous behavior of the flow equations.

The optimum values for DAMPS and DAMPT are model dependent. Values between 0.3 and 1.0 are commonly used. Values greater than one are used when the maximum errors become progressively smaller on successive iteration steps.

(Default value = 0.4)

Reference mass flow rate (lbm/s).

Element flow rate results will be presented in the output files both in terms of absolute flow rate in lbm/s and as a percentage of the reference flow rate, WREF.

(Default value = 1.0)

First global reference rotational speed (RPM).

The value for ELERPM1 will be used whenever an element selector variable RPMSEL, RPMSELR, or RPMSELL has a value of 1.0 and whenever a chamber or vortex RTR_IDX variable has a value of 1.

(Default value = 0.)

Second global reference rotational speed (RPM).

The value for ELERPM2 will be used whenever an element selector variable RPMSEL, RPMSELR, or RPMSELL has a value of 2.0 and whenever a chamber or vortex RTR_IDX variable has a value of 2.

(Default value = 0.)

Third global reference rotational speed (RPM).

The value for ELERPM3 will be used whenever an element selector variable RPMSEL, RPMSELR, or RPMSELL has a value of 3.0 and whenever a chamber or vortex RTR_IDX variable has a value of 3.

(Default value = 0.)

Maximum allowable number of flow iterations to reach a converged steady-state solution.

Flow Simulator will iterate up to this number of times in search of the converged solution of the flow network.

(Default value = 100)

Extra output print level

0: no extra output,

1: increase output amount

Convergence tolerance for the maximum percentage change in total pressure at any chamber from one iteration step to the next. PTTOL applies only to momentum and inertial chambers. The model will not converge until this tolerance is satisfied.

(Default value = 0.01%)

Convergence tolerance for the maximum allowable change in the fluid THETA flow Angle at any chamber from one iteration step to the next. THTOL applies only to momentum and inertial chambers. The model will not converge until this tolerance is satisfied.

(Default value = 0.1 deg)

Lower partial pressure limit whereby the fluid composition of a particular species is no longer considered in properties calculations. For example, if gas properties for a mixture of air and steam is needed for a calculation and the partial pressure of steam is less than this limit, the properties will be based on pure air.

(Default value = 0.1 psia)

Convergence tolerance for the maximum change in temperature (deg F) at any chamber. The model will not converge until this tolerance is satisfied.

(Default value = 1.0 deg F)

Flag that activates the FlowSimulator Whitney Damping feature, which seeks the optimal values of static pressure (DAMPS) and total pressure (DAMPT) damping based on the iterative progression of chamber errors.

0: Constant Damping - The input values of DAMPS and DAMPT are used for all iterations.

1: Whitney Adaptive Damping - The input values of DAMPS and DAMPT are used until iteration number ISTRTW. Subsequently, Whitney damping is activated and begins to automatically adjust the damping factors DAMPS and DAMPT at each iteration step. For most models this method gives the fastest solution.

2: Robust Whitney Damping - The input values of DAMPS and DAMPT are used until iteration number ISTRTW. Subsequently, a modified version of Whitney damping is activated. This modified version of Whitney damping may improve stability at the expense of speed.

(Default value = 1.)

FlowSimulator solver iteration when Whitney damping starts, provided Whitney damping is active (WHITNEY value of 1 or 2).

(Default value = 7.)

Controls how strongly the Whitney feedback is applied in modifying DAMPS and DAMPT from iteration to iteration.

Any non-negative number is allowable; however, setting it greater than the default risks unstable numerical behavior. Setting RMOD equal to a (non-negative) value much less than the default effectively disables Whitney damping.

(Default value = 0.05)

Upper bound for the damping factors DAMPS and DAMPT.

(Default value = 2.0)

Lower bound for the damping factors DAMPS and DAMPT.

(Default value = 0.2)

Flag used to specify whether or not supersonic Mach numbers (Mach > 1.0) will be permitted in momentum chambers. Suggested input is either 0 or 2 depending on whether supersonic flow should be allowed.

< 2.0 Mach number to be limited to 1.0. (0-Supersonic Momentum Chambers Disallowed)

≥ 2.0 Supersonic Mach numbers are permitted. (2-Supersonic Momentum Chambers Allowed)

In inertial chambers, supersonic values are always permissible and ISUPER has no effect. (Default value = 0. Supersonic flow in momentum chambers not allowed)

Transition value for Reynolds Number used in all tube elements.

For values of Reynolds Numbers within 5% of REYTRAN, the flow is assumed to be in transition. In the transition region a transition factor (between 0 and 1) is calculated as the ratio of (Reynolds Number minus 95% of REYTRAN) to (10% of REYTRAN). This transition factor is then used to linearly scale the values of friction factor, heat transfer coefficient, and adiabatic wall temperature between the fully laminar and the fully turbulent values.

For values of Reynolds Number above REYTRAN, turbulent flow values are used.

For values of Reynolds Number below REYTRAN, laminar flow values are used.

(Default value = 2300 providing a transition range from 2185 to 2415.)

0: ENG Units (Default)

10: SI Units

Identifies working fluid(s).

0 Fluid 1 is Ideal Air; Fluid 2 is Steam (Default)

1-11 Not supported in standard FlowSimulator

12 Fluid 1 is Ideal Air; Fluid 2 is a Real Gas

13 Fluids 1 and 2 are distinct Real Gases

17 Fluid 1 is CEA air; Fluid 2 is a CEA fuel

18 Fluid 1 is Ideal Air; Fluid 2 is a CEA fuel

(Default value = 0.)

If PROPS is set to 17 or 18, FlowSimulator will look for either a fuel source component or a name list in the model database that identifies the type(s) of CEA fuel used. PROPS = 17 will use CEA definition of air properties for working fluid 1 instead of using the FlowSimulator definition of air (types 0, 12, 18).

Radial tolerance (inches) for checking consistency of radius data for:

1. Elements connected to the same chamber
2. Vortex radii with associated cavity inflow and outflow radii (in).

Warning messages are issued for elements that do not meet the tolerance, but the solution process is not stopped.

(Default value = 0.01; Minimum = 0.001)

Solver Selection

0: Standard Solver (DEFAULT)

1: Robust Multi-Grid Solver

2: Transitional Solver

(Default value = 0.0)

Iteration when solver transitions from Standard Solver to Robust Solver if using the Transitional Solver option (SOLVER_TYPE=2).

(Default value = 0.0)

The maximum absolute difference between up-to-date vortex pressure ratio and damped vortex pressure ratio must be less than VTX_PR_TOL for the model to be declared converged.

Used for Robust Multi Grid & Transitional Solver (Default value = 1E-5)

The maximum absolute difference between up-to-date dynamic pressure ratio (PTS/PS) and damped dynamic pressure ratio must be less than DYN_PR_TOL for the model to be declared converged.

Used for Robust Multi Grid & Transitional Solver (Default value = 1E-5)

Specifies method of the initial internal (non-boundary) chamber and element value seeding for the Flow Simulator solver. Static pressures and total temperatures are seeded to the Flow Simulator solver for all of the methods below.

1: Initial values in the chamber data section of the model database file will be used as the initial guess for starting the Flow Simulator solution.

2: Compressible flow initializer will be called to produce improved initial values. Element flow rates are also seeded to the Flow Simulator solver.

10: If post-data (from a previously Flow Simulator solution) is available at the bottom of the database file, then the post-data will be used for seeding; otherwise the INITMODE = 1 option will be carried out.

20: If post-data is available, then post-data will be used; otherwise the INITMODE = 2 option will be carried out.

Default value is 0, which is interpreted as 1 by Flow Simulator. The Auto-Initialize function sets the INITMODE to 2

Controls printout of “*.dbg” file.

This file contains a record of the convergence path (chamber guesses and calculated chamber errors) for each iteration step during the solution process.

0: Do not write a “*.dbg” file.

10: Write a “*.dbg” file – Iteration History

(Default value = 0)

Controls printout of convmonitor_fi.out

0: Do not write a convmonitor_fi.out file.

1: Write a convmonitor_fi.out file.

(Default value = 0)

Controls printout of “*.res” file.

This is the principal output file, which contains solution results for chamber pressures, temperatures, steam fractions, and velocities as well as element flows and detailed element internal variables.

0: Do not write a “*.res” file.

1: Write a standard “*.res” file.

2: Write a “*.res” file at the end of the run, and after FlowSimulator iterations in which the cavity solver was run.

(Default value = 1)

Controls Transient Results file printout

0=write 1 file for each timestep (Default)

1=write 1 file for the entire transient

Controls printout of “*.rst.flo” file.

This file contains a database version of the model with solution post-data appended.

0: Do not write a “*.rst.flo” file.

1: Write a “*.rst.flo” file.

(Default value = 1)

Controls printout of “*.prop” file.

This file contains information about the resultant working fluid properties at each chamber.

0: Do not write a “*.prop” file.

1: Write a “*.prop” file.

(Default value = 1)

Controls printout of “*.cav.out” file.

This file contains cavity solver results for each cavity in the model.

0: Do not write a “*.cav.out” file.

1: Write a “*.cav.out” file with summary information and detailed information after convergence.

2: Same as #1, with detailed information printed after every cavity run.

3: Same as #1, with summary information printed after every cavity run.

4: Same as #1, with summary and detailed information printed after every cavity run.

(Default value = 1)

The “*.cav.out” file is only written if cavities are present.

Controls the Convergence History output in “convhist_fi.out” file

0: reduced residual items for output (writes Convergence History for every 10 iterations)

1: standard residual items

(Default value = 1)

Controls printout of element CD multiplier information in the for031.dat file for each FlowSimulator iteration. Inactive if W_31 equals 0.

0: Do not write CD multiplier information to the “*.dbg” file.

1: Write CD multiplier information to the “*.dbg” file for each iteration.

(Default value = 1)

Controls printout of the element flow derivatives in the for031.dat file for every element for each FlowSimulator iteration. Inactive if W_31 equals 0.

0: Do not write flow derivatives to the “*.dbg” file for each iteration.

1: Write flow derivatives to the “*.dbg” file for each iteration.

(Default value = 1)

W_31_MERR controls the printout of chamber momentum error at each FlowSimulator iteration step. Inactive if W_31 equals 0.

0: Write chamber momentum error to the “*.dbg” file on the final iteration.

1: Write chamber momentum error to the “*.dbg” file on every iteration.

(Default value = 0)

Controls printout of “*.XML” file.

This data file is in XML format and contains data that might be written to the “*.res” file plus some key input data. Users writing post processing tools are encouraged to get their data from this file rather than the “*.res” file.

0: Do not write a “*.XML” file.

1: Write a standard “*.XML” file.

(Default value = 0)

Controls printing of chamber data results table for every iteration for the screen.

0: Do not print chamber data results table to the screen & Convhist file for every iteration.

1: Print chamber data results table to the screen for every iteration.

2: Print chamber data results table to the Convhist file every iteration.

(Default value = 0)

Controls printout of CEA output data files from Combustion Elements and Chambers using CEA fluids.

(CEA_EL#_IT_#.out, CEA_CH#_IT_#.out).

0: No CEA files written out during run

1: Combustion elements print CEA output data only for the last iteration

2: Combustion elements print CEA output data for all iterations

3: Combustion elements and all Chambers print CEA output data only for the last iteration

4: Combustion elements and all Chambers print CEA output data for all iterations

(Default value = 0)

Controls printout of convergence history file.

0: Do not write convergence history

1: Write convergence history

(Default value = 1)

Tolerance for iteration-to-iteration change in Cp (Static Pressure Recovery Coefficient) for Diffuser elements.

(Default value = 0.001)

Controls how frequently properties are called in the Tube element. This improves run-time performance. If TLIM_FACT=1.0, then properties are called every time. TLIM_FACT=0.0 calls properties as sparingly as possible according to an adaptive scheme. The properties are updated according to how much total temperature has changed from the last properties call. TLIM_FACT of 0.5 has behavior that is between 0.0 and 1.0.

(Default value = 0.0)

Controls how frequently properties are called in the Tube element. This improves run-time performance. If PLIM_FACT=1.0, then properties are called every time. PLIM_FACT=0.0 calls properties as sparingly as possible according to an adaptive scheme. The properties are updated according to how much static pressure has changed from the last properties call. PLIM_FACT of 0.5 has behavior that is between 0.0 and 1.0.

(Default value = 0.0)

Maximum allowable number of iterations to reach a converged solution for the thermal network solver.

FlowSimulator will iterate up to this number of times in search of the converged solution of the thermal network.

(Default value = 100.)

Flag that specifies how FlowSimulator models should handle incompressible / compressible gas mixtures at chambers.

The values for the flag are:

0: All gas chambers - compressible

1: All gas chambers - incompressible

3: Treat chambers as compressible if at least one neighboring element is compressible

4: Treat chambers as incompressible if at least one neighboring element is incompressible

Controls printout of “.dbg” file for thermal networks.

This file contains a record of the convergence path (chamber guesses and calculated chamber errors) for each iteration step during the solution process.

0: Do not write thermal network debug information

1: Write a convergence summary

2: Write a convergence summary with the Jacobian at outer iterations

3: Write a convergence summary with the Jacobian at outer and inner iterations

(Default value = 0)

Chamber Temperature energy balance calculation procedure

0: T_Mixing_Default/ T_Mixing_Traditional→ Use 2nd order only for combustion models

2: T_Mixing_2nd_Order → Use new 2nd order T mixing, which works well when mixing different species

0: Defaults to 1 for transient runs, 2 for steady-state runs

1: Write WREF in files so user can choose any cycle flow as ref. flow

2: Use Fixed WREF as defined WREF input

Transient Results file output control

0: Don't write transient results file

1: Write transient results at each time step (Default)

2: Write transient results at each iterate of each time step

0: Write the history of controller variable values in the ”*.res” file output for Final timestep

1: Write only the current controller variable values in the ”*.res” output

2: Write the history of controller variable values in the ”*.res” output

Controls Shut off branch mass flow rate calculations

0: Shuts off the branches with closed elements with zero flow (Default)

1: Shuts of Closed Valve, & let the branches to calculate flows

2: Allow Closed Valves to leak & let the branches to calculate flows

-1: On → Solve as Incompressible Tube for any un-converged Compressible Tube due to low Mach number (Cut off Mach Number is 0.00012)

0: Off

0-1: Cut off Mach Number → Solve as Incompressible Tube for any Compressible tube with Mach less than cutoff

Global Vortex Flow Flag to overwrite the local vortex element flow flags.

Not Used.

Type of Analysis

STEADY_FLOW = 0

STEADY_FLOW_STEADY_THERMAL = 1

TRANSIENT_FLOW = 2

TRANSIENT_FLOW_TRANSIENT_THERMAL = 3

QUASI_STEADY_FLOW = 4

QUASI_STEADY_FLOW_TRANSIENT_THERMAL = 5

STEADY_THERMAL = 6

TRANSIENT_THERMAL = 7

WATER_HAMMER = 8

Constant Time Stepping: The time step is constant throughout the run.

Time Stepping based on Cycle/Mission Data: Time step is varied according to the min and max time steps assigned, along with the CFL numbers.

When using the “Constant Time Stepping” option, this is equal to the Time Step. For the “Time Stepping based on Cycle/Mission Data” option, also known as the Variable time step, this will be upper bound of the Time Step variable.

Iteration when solver transitions from Standard Solver to Robust Solver if using the Transitional Solver option (SOLVER_TYPE=2).

(Default value = 0.0)

Options for Sink Chamber Output

0: Calculates based on flow Entering the chamber (Default)

1: Retain User inputs

Unit System for Wave Speed estimate

0: ft/sec

1: m/sec

Method Flag to determine Flow Direction calculation method

0: TRADITIONAL__METHOD (Default)

1: MODERN_FLOW_SIMULATOR_METHOD

10: AUTO_BEST_FLOW_DIRECTION_METHOD (COMBINATION OF 0 & 1)

Controls Temperature change due to Gravity & Pumping

0: No Change

1: Isentropic T Change

Controls/Modify Tube Wall T, HT etc

0: Run the Model with heat transfer (Default)

2: All Adiabatic (Disables all Heat transfer calculations)

Chamber fluid pressure lower limit in psia.

Default = .001 psia for gas and -20,000 psia for liquid. A negative pressure for liquids indicates cavitation.

Chamber fluid temperature damping factor.

1: No Damping (Default)

0.01 – 1: Enter Number from (0.01 - 1)

99: Automatic Damping