Setting Up the Smart Sweep Study

To model the air compressor performance, you set up a smart sweep study in Design Manager.

You start the smart sweep study with a mass flow value close to the compressor choke point and reduce the mass flow value progressively towards the surge line of the air compressor. The surge line is detected by the bisect criterion—when the stage total pressure ratio drops below 3%. After bisect starts, the step size is reduced to half. A stopping criterion is set, the smart sweep stops running when one bisect is complete.

You can create more speedlines by investigating different rotational rate. To reduce the solution time for this tutorial, you only consider a fixed rotation rate of 1800 radian/s.

To create a Design Manager Project:
1. Open the reference simulation Stage37_smartsweep_ref.sim, right-click the Stage37_smartsweep_ref node and select Create Design Manager Project.
2. Save the Design Manager project as Stage37_smartsweep_project.dmprj.
To specify the design study type:
1. Right-click the Design Studies node and select New.
2. Select the Design Study node and set the Study Type to Smart Sweep.
  For generic workflow of a smart sweep study, refer to Setting Up a Smart Sweep Study.
  For the reference topic of the smart sweep settings, refer to Smart Sweep Settings Reference.
In the smart sweep study, you vary the mass flow at the stator outlet and plot the stage total pressure ratio with respect to the mass flow:
1. To set the mass flow as input parameter, select the Design Study > Input Parameters node and add massflow to the Parameters.
2. To define a sweep, right-click the Input Parameters node and select Edit.
3. In the Design Table, select Add Row and specify a sweep with a mass flow value 0.448 kg/s.
  This value defines the first run of this sweep.
4. To set the responses, select the Design Study > Responses node and add StageTotalPressureRatio to the Responses.

To start a sweep (speedline), you specify stepping parameter as step size between runs, bisect criteria, and stopping criteria. The design runs with the step size increment until the bisect happens. After bisect the step size is halved progressively at each design run until the stopping criteria of this sweep are fulfilled.

Right-click the Smart Sweep Settings node and make sure that Reuse designs within search is activated.
For non-critical operating conditions (far from choke or surge areas), slight changes in the mass flow do not change the flow pattern significantly. In this case, reusing results from previous design runs in combination with monitor criteria can reduce the simulation time considerably. In the critical areas, the changes in the flow pattern are significant and therefore, reusing results from previous design runs does not have a significant effect on the solution time.
For designs with more sweeps, also activate Reuse designs across search.
Right-click the Smart Sweep Settings > Stepping Parameter node and add massflow to the Study Parameter.
Select the massflow node and set the Step Size to -2.5e-4 kg/s.
The mass flow is continuously reduced within the sweep.
To define a bisect criterion, right-click the Bisect Criteria node and select Create New Criterion.

Select the Response Criterion node and set the properties as follows:


Node	Properties	Values
Response Criterion	Study Response	Stage Total Pressure Ratio
Response Criterion	Criterion Option	Percentage Change
Percentage Change	Percentage Change	-3.0

To create a stopping criterion, right-click the Stopping Criteria node and select New > Step Size Criterion.

Select the Step Size Criterion node and set the properties as follows:


Node	Properties	Values
Step Size Criterion	Criterion Option	Number of Bisects
Number of Bisects	Number of Bisects	1

The smart sweep design study stops after the step size is bisected (halved) once.