- boundaryThe list of boundary IDs from the mesh where this boundary condition applies
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:The list of boundary IDs from the mesh where this boundary condition applies
- fpSingle-phase fluid properties
C++ Type:UserObjectName
Controllable:No
Description:Single-phase fluid properties
- p_exitOutlet pressure at nozzle exit
C++ Type:double
Controllable:No
Description:Outlet pressure at nozzle exit
SpecificImpulse1Phase
Estimates specific impulse from fluid state at a boundary
Discussion
Specific impulse is a measure of how much thrust is produced by an exhaust gas per mass flow rate. Specific impulse is denoted by and defined as:
where , is thrust, and is the mass flow rate. Specific impulse has units of seconds. This equation can be generalized to an averaged over a transient burn where the quantities on the right hand side may depend on time.
The postprocessor allows to switch between instantaneous and averaged using the accumulative parameter.
The postprocessor computes by assuming an isentropic change of state from the conditions on the boundary to outlet conditions. The outlet pressure must be provided to parameter p_exit. It is assumed that the expansion is perfect:
The outlet area expands the gas exactly to
p_exit. If the ambient pressure is not equal to the resulting pressure from the expansion characteristics of the nozzle, a real nozzle would experience a shock that reduces its efficiency. The possible occurrence of a shock is neglected.Losses and heat transfer are neglected.
Input Parameters
- bisection_max_it100Maximum number of iterations for bisection to find h(entropy_in, p_out)
Default:100
C++ Type:unsigned int
Controllable:No
Description:Maximum number of iterations for bisection to find h(entropy_in, p_out)
- bisection_tolerance0.0001Tolerance for bisection to find h(entropy_in, p_out)
Default:0.0001
C++ Type:double
Controllable:No
Description:Tolerance for bisection to find h(entropy_in, p_out)
- cumulativeTrueIf specific impulse is accumulated over timesteps. If false, then instantaneous value is computed
Default:True
C++ Type:bool
Controllable:No
Description:If specific impulse is accumulated over timesteps. If false, then instantaneous value is computed
- execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM, ALWAYS.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Controllable:No
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM, ALWAYS.
- prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
- variablesrhoA rhouA rhoEA A Single-phase flow variables
Default:rhoA rhouA rhoEA A
C++ Type:std::vector<VariableName>
Controllable:No
Description:Single-phase flow variables
Optional Parameters
- allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Controllable:No
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
- control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
- enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:Yes
Description:Set the enabled status of the MooseObject.
- force_postauxFalseForces the UserObject to be executed in POSTAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in POSTAUX
- force_preauxFalseForces the UserObject to be executed in PREAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREAUX
- force_preicFalseForces the UserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup
- outputsVector of output names were you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector<OutputName>
Controllable:No
Description:Vector of output names were you would like to restrict the output of variables(s) associated with this object
- use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Controllable:No
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.