Madrid y el Plan Técnico Nacional de Televisión Digital Local

This model is similar to the Full Model type except the fact that the detailed input of the performance maps is done in the BOOST Turbocharger Tool (refer to the

BOOST_TurbochargerTool.pdf for information). Remaining input is Mechanical

Efficiency, Moment of Inertia and Initial Speed on the main page, the Performance Map File (exported from the Turbocharger Tool) and the possibility to scale the individual positions of the imported maps by means of a Mass Flow Scaling Factor and an Efficiency Offset/Scaling Factor on the subpage.

For both Turbine and Compressor part the Variable Geometry option is given, which means an interpolation between input maps of different position is performed. If no Initial Position is given the first position is assumed to be the initial one.

The input of the Turbine is completed with the Initial Turbine to Total Mass Flow and an Interference Coefficient for Twin or Multiple Entry Turbines.

4.14.2. Turbine

4.14.2.1. Simplified Model

The Simplified Model allows the user to specify an operating point, defined by the turbine massflow, volume flow, or Equivalent Discharge Coefficient, and the isentropic efficiency, irrespective of the actual conditions at the turbine. As an alternative an iso-speed line may be defined by the user. This model should be used for steady state simulations only.

For the simulation of a mechanically linked turbine, AVL BOOST requires the specification of the performance characteristics of the turbine along a line of constant turbine speed, the specification of the Mechanical Efficiency, which pipes are attached to the inlet and to the outlet of the turbine, and to which component the turbine is

mechanically linked.

The Corrected Mass Flow, Corrected Volume Flow or Equivalent Turbine Discharge Coefficient and the Isentropic Efficiency may be specified versus Turbine Pressure Ratio for a line of constant turbine speed. For a simplified approach, also constant values for these values may be specified.

For the Flow Type Equivalent Turbine Discharge Coefficient a related Reference Area is required, while for Corrected Mass Flow and Corrected Volume Flow Reference Conditions have to be specified.

The Mechanical Efficiency covers mechanical friction losses of the turbine wheel.

In the case of a twin-entry turbine, an Inlet Interference Flow Coefficient has to be specified in order to describe the interference between the attached pipes. The inlet interference flow coefficient is related to the cross section of the actual pipe modeling the turbine inlet. For radial type turbines an inlet interference flow coefficient of 0.2 and for axial type turbines a value of 0.05 is recommended.

A simplified Waste Gate Calculation can be performed by specifying a Turbine Massflow to Total ratio less than 1.

4.14.2.2. Full Model

The Full Model allows the user to specify a full map of the turbine. The instantaneous operating point will be calculated from the turbine speed (determined from the mechanically linked component) and the conditions at the turbine in- and outlet.

The following turbine types are available for defining the turbine performance map:

Twin entry – VTG - simplified model: For a twin entry VTG only the simplified model is available.

Multiple entry - simplified model: Only one map is specified. The map is measured with the same pressure ratio across all flows of the turbine. The interaction between the flows can be modeled by the definition of a suitable inlet interference coefficient.

Multiple entry – VTG - simplified model The vane position must be set for VTG’s.

In a turbine map the swallowing capacity is plotted versus the pressure ratio across the turbine with the wheel speed as parameter. The isentropic efficiency can be plotted in the same way or it can be plotted versus the blade speed ratio. BOOST supports the input of both map types. The suitable units for the definition of the swallowing capacity and the reference conditions can be selected from predefined lists. Similar to the compressor map, the data for the definition of each point in the map must be input by the user. For each map a mass flow scaling factor allows the user to scale the swallowing capacities specified and an efficiency offset to modify the efficiencies additively.

Map Visualization

For details please refer to the corresponding section of the Turbocharger Turbine (section 4.14.1.2.2).

4.14.2.3. Full Model with Turbocharger Tool Performance Maps

This model is similar to the Full Model type except the fact that the detailed input of the performance maps is done in the BOOST Turbocharger Tool (refer to the

BOOST_TurbochargerTool.pdf for information). Remaining input is Mechanical

Efficiency, Moment of Inertia and Initial Speed on the main page, the Performance Map File (exported from the Turbocharger Tool) and the possibility to scale the individual positions of the imported maps by means of a Mass Flow Scaling Factor and an Efficiency Offset/Scaling Factor on the subpage.

For the Turbine the Variable Geometry option is given, which means an interpolation between input maps of different position is performed. If no Initial Position is given the first position is assumed to be the initial one.

The input is completed with the Initial Turbine to Total Mass Flow and an Interference Coefficient for Twin or Multiple Entry Turbines.