Dirk Schönweitz

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.

Novel Performance Prediction of a Transonic 4.5 Stage Compressor

Computing capacities have grown exponentially in recent years and 3D-Navier-Stokes methods were developed widely. However it is still not feasible to design a multi-stage compressor directly in three dimensions. Instead, compressor design starts with 1D-design. In accordance with this approach, basic parameters such as the number of stages and stage pressure ratios are determined. In the following 2D-design, the geometry of the flow channel and the main parameters of the blade geometries can be determined. Afterwards in the 3D-design, unsteady and 3D-flow-effects are considered and the design optimized accordingly. Therefore, it is virtually impossible to correct conceptual faults in the 3D-design phase. Thus a robust and reliable 2D-Throughflow-solver including a performance prediction for modern airfoil geometries is necessary. So far there is no efficient methodology known which predicts the performance for all kinds of airfoil geometries, as it would be necessary in a 2D-Throughflow optimization process. In [1, 2] a novel methodology was presented, which is able to predict the performance for a large number of airfoil geometries accurately. This method is based on a large airfoil database which is used to train a surrogate model for airfoil performance prediction. The scope of this work is to validate and to document the progress of this new approach. In Schmitz et al. [1] it was validated on rotor 1 of the 4.5 stage transonic test compressor DLR-RIG250 of the Institute of Propulsion Technology. In this work all 4.5 stages were calculated at different speedlines and different vane positions. The results of the S2-solver are compared to experimental data and 3D-CFD calculations, obtained using the DLR in-house solver TRACE.Copyright

Integration- and Intake-Induced Flow Distortions and Their Impact on Aerodynamic Fan Performance

This paper provides a general overview of the most recent activities at DLR’s Institute of Propulsion Technology dedicated to the appraisal of fan performance under the influence of installation and intake induced flow distortions. Most of the results are to be considered work in progress and the intention of this paper is to merely provide a general overview of the current research demands for current and future propulsors powering medium and largely sized engines. The first part of the paper summarizes a ground induced inlet distortion study carried out with the V2500 transonic fan stage. One of the objectives was to provide reference results for a realistic and engine representative fan stage with a relatively high fan total pressure ratio. Full scale measurements were taken at DLR’s research aircraft ATRA, allowing for a visualization of the flow structures ingested by the fan and a direct comparison with computational data from full annulus, fully coupled and unsteady CFD simulations of the entire ground, nacelle, intake, and fan system. The second part summarizes the comparison of the sensitivity of the operational behavior of two fans with different total pressure ratios towards a generic yet realistic inlet distortion. Results from unsteady CFD computations of the V2500 fan will be compared with those of a research fan with a substantially lower fan pressure ratio (Fan135). The focus of the third part of this paper is to introduce a design methodology for closely coupled intake and fan systems and to present results from a preliminary design study, aiming at short and ultra-short inlets in combination with a fan pressure ratio FPR=1.35 fan being representative for future UHBR engines.

Sensitivity of a Low Pressure Ratio Jet Engine Fan to Inlet Distortion

As part of future civil aircraft concepts the integration of jet engines is considered as an additional possibility to increase the efficiency of the whole aircraft. While the ingestion of the fuselage boundary layer reduces the drag of the aircraft it also causes the fan stage of the engine to operate with a distorted inflow. In this study, a fan with a low total pressure ratio, representing future fan designs, and the fan of the International Aero Engines (IAE) V2500 engine, representing a common fan design in today’s jet engines, are imprinted with a parameterized generic but also realistic inlet distortion. The numerical investigation of both fans that employed transient full-annulus simulations showed that regarding different criteria the low pressure ratio fan is more sensitive to the imprinted inlet distortion.