Detached Eddy Simulation for Aerospace Applications
Doctoral thesis, 2021

With the continuous growth in air traffic that we see nowadays, comes an increase in the requirements needed to be satisfied in order to certify an aircraft for operation. These stricter regulations affect aspects such as CO2 emissions, sound pollution and so on, pushing manufacturers to aim for lighter, more efficient, more robust designs. These improvements might be achieved in two different ways; by improving/optimizing existing technology, or by developing new technological concepts. In either of the two scenarios, numerical tools, such as optimization methods or reliable fluid flow simulations play a paramount role.

In this thesis, new functionalities implemented into the in-house compressible Computational Fluid Dynamics (CFD) solver, G3D::Flow, are described. These new additions have been put in place with the objective of performing turbomachinery simulations using hybrid RANS/LES methods as well as nozzle flow simulations. Some of the additions to G3D::Flow include: phase-lagged pitch-wise and rotor-stator interfaces based on the chorochronic method as well as a method based on Proper Orthogonal Decomposition (POD), sliding grid interface and synthetic turbulence injection. The added capabilities, enable G3D::Flow to perform high-fidelity turbomachinery CFD simulations, which were not affordable before due to their high computational cost, since truncated domains can be used.

A hybrid RANS/LES simulation of the VOLVO S6 nozzle contour operating under overexpanded conditions is performed. This same geometry, under the same conditions, was previously simulated and reported using a different hybrid RANS/LES methodology. A reduction of over $50\%$ in the difference between the predicted standard deviation of the side loads and those measured in a previous experimental is observed in the current simulation.

In this work, an optimization framework called HAMON is also presented, which is based on evolutionary algorithms. In cases where the optimization is based on computationally heavy tasks, such as 3D CFD simulations, meta-modeling techniques can be used to speed up the optimization processes. HAMON can be used to fine tune an existing design, or as it has been used here, as black-box approach. It has been able to design counter rotating open rotors with more than acceptable performance where no knowledge about propeller aerodynamics was assumed, giving all the design variables more freedom than probably needed. This black-box approach might be specially useful when optimizing new technologies for which no prior knowledge exist, allowing not only to, hopefully, find good designs but also to show the trends of what a good design should be like.

Stochastic optimization

Synthetic turbulence

CFD

POD based phase-lag

Hybrid RANS/LES

LODI

Phase-lagged boundary conditions

Nozzle flow separation

Evolutionary algorithms

Chorochronic

Sliding grid

KA lecture hall, Kemigården 4. -- ZOOM PASSWORD: 580735
Opponent: Prof. Paul G. Tucker, Cambridge University, United Kingdom

Author

Gonzalo Montero Villar

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Aeroacoustic Analysis of a Counter Rotating Open Rotor based on the Harmonic Balance Method

2018 AIAA Aerospace Sciences Meeting,; Vol. 2018(2018)

Paper in proceeding

Initial test of SVD based Phase- Lagged Boundary Conditions for Turbomachinery Simulations in the G3D::Flow Solver

Nozzle Side Loads Prediction using a Hybrid RANS/LES Method

Over the past decades, air traffic has been continuously increasing, and there seem to be no sign of it slowing down in the foreseeable future. This is having a considerable impact in greenhouse emission gases, therefore, the minimum requirements for certifying an aircraft are getting more stringent. Numerical tools are going to play a huge role in this, as they are a key aspect when it comes to designing more robust, more efficient, lighter aircraft components as well as lighter and safer rocket nozzles.

In this work a fully automated optimization platform based on evolutionary algorithms is implemented, which can be used to either fine-tune an existing components, or to generate new ones relying on very little previous knowledge. This has been shown by designing a counter rotating open rotor where almost zero knowledge of aeronautics was provided to the optimizer. The obtained designs got more than acceptable performance.

Moreover, being able to accurately simulate fluid flows in different turbomachinery components or rockets nozzles is of great importance, not only to aid in the design process, but also to help in the understanding the complex fluid flow phenomena that occur. Therefore, during this work, several additions to the in-house CFD code G3D::Flow have been made. This have been put into place with the aim of performing high-fidelity fluid flow simulation on turbomachinery components while using truncated domains, as well as being able to predict the forces acting on a rocket nozzle. High fidelity simulations where side loads acting on a nozzle contour were performed, showing excellent agreement with experimentally measured data and improving previously obtained numerical results by over 50%.

Detaljerad Flödesanalys för Rymdmunstycken (DFR)

Swedish National Space Board (20/19), 2019-04-01 -- 2021-03-31.

Validation of improved turbomachinery noise prediction models and development of novel design methods for fan stages with reduced broadband noise (TurboNoiseBB)

European Commission (EC) (690714), 2016-09-01 -- 2020-02-29.

Areas of Advance

Transport

Subject Categories

Aerospace Engineering

Computational Mathematics

Fluid Mechanics and Acoustics

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7905-574-5

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5041

Publisher

Chalmers University of Technology

KA lecture hall, Kemigården 4. -- ZOOM PASSWORD: 580735

Online

Opponent: Prof. Paul G. Tucker, Cambridge University, United Kingdom

More information

Latest update

10/28/2021