“Online Throughflow”: Automatic Simultaneous Simulation of an Axial Flow Turbine

A new turbine rig analysis method has been developed at the Institute of Aircraft Propulsion Systems (ILA) at Stuttgart University. This technique is known as “Online Throughflow” and involves the optimized adjustment of the input parameters of a Throughflow Method. The calculation is run whilst the turbine is being tested, achieving a match to measured data in about five minutes. The match between predicted and measured data is expressed as a chi-squared value. This provides a target parameter for a linear optimization procedure. Measured parameters such as inter-row static pressures, torque, mass-flow and rotational speed are used in this context. Input parameters such as row deviation and row loss are adjusted to give an optimized turbine simulation in close to real time. Less than five minutes after taking a data scan of the experimental parameters at inlet to exit from and within the turbine, a converged simulation of the turbine is available. This simulation evaluates many other parameters within the turbine that are not directly measured, e.g. circumferential exit flow angles for all rows of aerofoils. Furthermore the single values of chi-squared from every measured variable can be used to decide if there is an error in the individual measurements. The complete optimizer is programmed in LabView^® and is integrated into the data acquisition system of the two-stage “Advanced Turbine Research and Demonstration Rig” (ATRD-Rig), which has been developed in a cooperation of ILA and the MTU Aero Engines (MTU). The testbed, as well as the instrumentation of the specific specimen from which all measurement values for the optimization have been taken, will additionally be described in the paper.