Use the duct component to model components just passing flow to the next component at the expense of an amount of pressure loss or when a user specified heat flux must be added to or taken from the gas. Note that the duct only provides a simple means to model heat transfer using a design and/or an off-design heat flux.
Often, secondary air flows from other components such as compressors 'leak' into the duct. To model this effect, bleed flows can be specified to enter the duct, using the table in the Bleed in-flow tab sheet. Use the bleed flow numbers to identify the appropriate compressor bleed flows, and specify the fractions of bleed flows actually entering the duct. In case the corrected entry mass flow is used for the pressure loss calculation, this flow does not include the bleed flows! By definition bleed flows bleed into the entry of the duct. If bleed in-flow functionality e.g. halfway the duct component is to be modeled, the modeler should use two ducts in series using the inflow of the second duct.
An unlimited number of duct bleed flows can be specified in the Bleeds tab sheet. Duct bleed flows are secondary air flows extracted from the duct air flow for various purposes: bleed flows can be used to model customer bleeds or turbine cooling bleeds used in the turbine component, etc. The bleed flow numbers used must be unique for the model.
Duct
