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This paper shows the application of the aerodynamics exergy analysis preliminary formulation developed for unsteady flows for adiabatic and fixed bodies under low subsonic flow conditions (no shock-waves). The numerical implementation for URANS CFD cases of the presented formulation is explained. The test case is a circular cylinder in vortex shedding regime at Reynolds number 140, at low subsonic flow, with no movement with respect to the reference frame. The validation of the developed formulation is done by comparing the drag coefficient computed by the presented unsteady exergy formulation versus the near field drag coefficient taken as reference.

In 2020, ISAE-SUPAERO has released the first version of Epsilon: an open source tool for the aerodynamic analysis of CFD data with Paraview [1]. Several methods were available: near-field, far-field, Lamb vector and exergy. In the original release, CFD data could be fully analyzed but the analysis of wind tunnel data was very limited. That is why a development effort was undertaken in order to improve the posttreatment capabilities of wind tunnel data. Several tools were created to properly perform an aerodynamic analysis from PIV and 5HP data. These developments were implemented and verified in a recent wind tunnel campaign and the resulting feedback was used to perform a further upgrade to the software. The resulting new version of Epsilon is released to the public along with this conference paper.

The aerodynamic analysis by the exergy method is a powerful approach which allows establishing the theoretical limits of the aerodynamic performance of a given body, based on an aero-thermodynamic approach. The most used formulation is the Arntz’s method [1], which is well suited for the analysis of CFD data. This formulation was widely applied and validated for plenty of test cases but all of them were high-aspect ratio configurations. Then, the objective of this work is to study a test case with low aspect ratio: a delta wing with 74° of sweep angle, which is characterized by extreme flow features like strong vortices. It was found that the exergy formulation behaves well even under such challenging conditions. However, the related extreme flowfield allows identifying some hard points like the wake-reduced exergy analysis of the vortex breakdown, the impact of the solver setting on the final assessment, the viscous anergy generation, among other topics.

The aerodynamic analysis by the exergy method is reviewed. The existing formulations are analyzed for an external flow test case (NACA 0012 airfoil). This lead to the detection of some discrepancies between the CFD-based formulation and the wind-tunnel-based formulation, as well as other inconsistencies. Hence, a new harmonized formulation (based on the original Arntz’s work [1]) is proposed, providing consistent results for both, CFD and wind-tunnel approaches.

This paper presents the open source code called “Epsilon”. It is a tool suited for the aerodynamic analysis of CFD and wind tunnel data by using the exergy method. Other methods are also provided (near-field, far-field, Lamb vector). The architecture of the code is presented as well as a qualitative description of the analysis capabilities provided by the tool. Some reference test cases are presented and an accuracy assessment of the exergy analysis is performed. The software is released to the public along with this conference paper.

This paper aims to provide a prediction method for the transverse exergy of the wing’s trailing vortices. It relates the transverse exergy at each point of the entire downstream survey plane to the vorticity inside the wake. This allows reducing the survey area to the wake region only, leading to a useful expression for the calculation of the transverse exergy from wind tunnel measurements. The proposed equation offers a significant improvement respect to the Maskell method especially at high-angle of attack condition. CFD analyses of a NACA 0012 rectangular wing at subsonic and transonic conditions were used as test cases to present the concept.