Paul-Benjamin Ebel

Aerodynamic Performance Characteristics of the Installe V2527 Fan at Ground Operation

This paper describes the aerodynamic assessment of the V2500 fan stage during ground operation at maximum fan rotational speed. In order to analyze the ground effect and resulting vortex ingestion into the fan, full annulus uRANS computations of the fan including the nacelle and the ground were performed. The numerical results were used prior to the tests at DLRs research aircraft ATRA to support planning the experimental setup in terms of measurement plane location and seeding introduction. In return, the obtained PIV measurement results were used to verify the numerical data. In particular, the formation of the ground vortex, although its location being highly unstable in the experiments, was observed in both, numerical and experimental results in a very similar fashion and its characteristics could be studied in detail. The numerical results furthermore allowed for a detailed assessment of the interaction between this incoming vortical distortion and the fan blades. Apart from high-fidelity uRANS computations, the fan performance over the entire speed range or fight regime respectively was evaluated by single passage and steady state RANS simulations. Appropriate boundary conditions were derived from a thermodynamic cycle model of the entire engine which was validated with available data from engine acceptance tests. The CFD results in terms of performance characteristics were then introduced again into the cycle model to update and further improve the cycle model.

Modelling and Validation of a V2500 Honeycomb-Core Fan Blade

Structural mechanics and also aerodynamics and aero elastics have a need for detailed and exact models of the regarded structures to create reliable results. The Institute of Structures and Design of the German Aerospace Center (DLR) located in Stuttgart has considerable experience in the field of mechanical analysis, design and assessment of aero engine structures as well as in the processing of these structures for further applications in aerodynamics and aero elastics. It is important to ensure that the hereby used methods in modelling and simulation are producing authentic results and the created data is feasible for usage in the linked disciplines. Therefore, the simulated behavior of a fan blade model of the engine of DLR research aircraft A320-ATRA (Advanced Technology Research Aircraft) was validated with measurements of real fan blades during the SAMURAI project. The paper describes a modelling technique for a fan blade with titanium honeycomb core in its context of an IAE V2500 aero engine based on provided CAD-data, x-ray and CT scans and measurements on existing structures. The fan blade model and particularly the influence of the honeycomb core were validated against Eigen frequencies and masses of real blades. With this baseline, simulations for several loading cases respectively several operating points were performed. The gained results were used on the one hand for aerodynamics and engine performance calculations in the context of the project and on the other hand for comparison with fan blade deformations which were determined by IPCT-measurements (Image Pattern Correlation Technique) on the real engine in operation.

Image Based Fan Blade Deformation Measurements on an Airbus A320 V2500 Engine in Ground Operation

The Image Pattern Correlation Technique (IPCT) was applied to measure the fan blade deformation of the IAE V2527 engine operating at Maximum Continous Thrust (MCT). The ground test on the DLR research aircraft A320-ATRA was a main part of the DLR project SAMURAI which wanted to use the ‘Synergy of Advanced Measurement Techniques for Unsteady and High Reynolds Number Aerodynamic Investigations’. The stereo camera system was fixed in front of the left engine. For certification reasons the correlation pattern had to be projected to the fan by a laser. The IPCT evaluation were improved to cope with the special challenges of the measurement and to enable a comparison with Computational Structural Mechanics (CSM) results finally.

Forced Response Analysis of a transonic fan

The forced response of turbomachinery blades is a primary source of high cycle fatigue (HCF) failure. This paper deals with the computational prediction of blade forced response of a transonic fan stage that consists of a highly loaded rotor along with a tandem stator. In the case of a transonic fan, the forced response of the rotor due to the downstream stator assumes significance because of the transonic flow field. The objective of the present work is to determine the forced response of the rotor induced as a result of the unsteady flow field due to the downstream stator vanes. Three dimensional, Navier-Stokes flow solver TRACE is used to numerically analyse the forced response of the fan. A total of 11 resonant crossings as identified in the Campbell diagram are examined and the corresponding modeshapes are obtained from finite element modal analysis. The interaction between fluid and structure is dealt with in a loosely coupled manner based on the assumption of linear aerodynamic damping. The aerodynamic forcing is obtained by a nonlinear unsteady Navier-Stokes computation and the aerodynamic damping is obtained by a time-linearized Navier-Stokes computation. The forced response solution is obtained by the energy method allowing calculations to be performed directly in physical space. Using the modal forcing and damping, the forced response amplitude can be directly computed at the resonance crossings. For forced response solution, the equilibrium amplitude is reached when the work done on the blade by the external forcing function is equal to the work done by the system damping (aerodynamic and structural) force. A comprehensive analysis of unsteady aerodynamic forces on the rotor blade surface as a result of forced response of a highly loaded transonic fan is carried out. In addition, the correspondence between the location of high stress zones identified from the finite element analysis and the regions of high modal force identified from the CFD analysis is also discussed.

Fan Blade Deformation Measurements on the DLR Airbus A320-ATRA by Means of IPCT as Part of the Ground Test Campaign in the Frame of the DLR-project SAMURAI

The Image Pattern Correlation Technique (IPCT) was applied to measure the fan blade deformation of the IAE V2527 engine operating at Maximum Continous Thrust (MCT). The ground test on the DLR research aircraft A320-ATRA was a main part of the DLR project SAMURAI which wanted to use the ‘Synergy of Advanced Measurement Techniques for Unsteady and High Reynolds Number Aerodynamic Investigations’. The stereo camera system was fixed in front of the left engine. For certification reasons the correlation pattern had to be projected to the fan by a laser. The IPCT evaluation were improved to cope with the special challenges of the measurement and to enable a comparison with Computational Structural Mechanics (CSM) results finally.