Thorsten Lutz

Thorsten Lutz
Universität Stuttgart · Institute of Aerodynamics and Gasdynamics

Dr.-Ing.

About

280
Publications
59,410
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2,956
Citations
Citations since 2017
137 Research Items
2080 Citations
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20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
January 1992 - present
Universität Stuttgart

Publications

Publications (280)
Preprint
Full-text available
This work provides an overview of aerodynamic data acquired in the European Transonic Windtunnel using an XRF-1 transport aircraft configuration both at cruise conditions and at the edges of the flight envelope. The goals and design of the wind tunnel test was described, highlighting the use of the cryogenic wind tunnel's capability to isolate the...
Article
The aerodynamics of transport aircraft at the borders of the flight envelope is characterized by complex interactions and nonlinear, unsteady flow phenomena. The underlying physical mechanisms are not fully understood, and a prediction of aerodynamic properties, transient loads, and aeroelastic behavior is a major challenge that requires the use of...
Article
In this paper, measurements of the stall of a NACA 64(3) – 418 airfoil section are presented and compared to a simulation with a hybrid Reynolds-averaged Navier–Stokes (RANS)/large-eddy simulation (LES) model with the goal of gaining deeper insight into the flow physics of a stall cell and the turbulent wake in such conditions. Detailed measurement...
Preprint
Full-text available
This paper provides a summary of the work done within Phase III of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty project (OC6), under International Energy Agency Wind Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating suppo...
Article
Full-text available
This paper shows the results of computational fluid dynamics (CFD) studies of turbulent flow fields and their effects on a wind turbine in complex terrain. As part of the WINSENT project, a research test site comprising four meteorological masts and two research wind turbines is currently being constructed in the Swabian Alps in southern Germany. T...
Article
Full-text available
This paper shows high-fidelity fluid–structure interaction (FSI) studies applied to the research wind turbine of the WINSENT (Wind Science and Engineering in Complex Terrain) project. In this project, two research wind turbines are going to be erected in the south of Germany in the WindForS complex-terrain test field. The FSI is obtained by couplin...
Article
Full-text available
The surface pressure fluctuations, which are a source of low-frequency noise emissions, are numerically investigated on a 2 MW wind turbine under different inflow conditions. In order to evaluate the impact of a complex-terrain flow, a computational setup is presented that is aimed at reproducing a realistic flow field in the complex terrain in Per...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-3955.vid The integration of electrically driven powertrain components in the aircraft design enables new design concepts and the use of unconventional technologies. Therefore, this paper investigates the aerodynamic propeller-wing interaction, the wing structure and their combined effect on th...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-3300.vid Wingtip-mounted propellers (WTP) can increase the overall efficiency of an aircraft via positive aerodynamic interactions between the propellers and the wing vortex system. The effect of a WTP thereby depends to a large extent on the propeller design. CFD-based parametric studies on t...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-3217.vid Aerodynamic propeller-wing interactions of a distributed propulsion system in a high-lift scenario were investigated as part of the Clean Sky 2 project DISPROP. A 2.5D CFD parameter study with steady-state RANS simulations of a wing segment and an Actuator Disk was conducted to determ...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-3818.vid The influence of wind-tunnel installation effects on a distributed propulsion configuration is investigated as part of the Clean Sky 2 project DISPROP. Simulations of wind-tunnel flow are compared with simulations assuming an undisturbed free stream surrounding the powered wing flow a...
Article
Full-text available
The results of high fidelity aerodynamic and acoustic computations of thick flatback airfoils are reported in the present paper. The studies are conducted on a flatback airfoil having a relative thickness of 30% with the blunt trailing edge thickness of 10% relative to chord. Delayed Detached‐Eddy Simulation (DDES) approaches in combination with hi...
Article
Full-text available
Modern wind turbines are increasingly equipped with vortex generators in the inner part of the rotor blade. On large blades it is usual to install hundreds of these small passive devices to delay flow separation. Therefore, affordable numerical methods to include vortex generators in the design process are required. One very promising method based...
Article
Full-text available
A high-fidelity process chain is used to numerically investigate the low-frequency emissions from a generic wind turbine under turbulent inflow conditions. It consists of the Computational Fluid Dynamics (CFD) solver FLOWer , which is coupled to the multi-body simulation software SIMPACK to take unsteady aeroelastic effects into account. A realisti...
Article
Full-text available
Helicopters are used for offshore wind farms for maintenance and support flights. The number of helicopter operations is increasing with the expansion of offshore wind energy, which stresses the point that the current German regulations have not yet been validated through scientific analysis. A collaborative research project between DLR, the Techni...
Chapter
This chapter focuses on the challenges rising when modeling the aeroelasticity of modern wind turbines utilizing high-fidelity methods. A comprehensive review of the state of the art is presented at the beginning, including engineering models. Since the aeroelastic models consist of a flow and a structural solver, a detailed description of the mode...
Preprint
Full-text available
This paper shows high-fidelity Fluid Structure Interaction (FSI) studies applied on the research wind turbine of the WINSENT project. In this project, two research wind turbines are going to be erected in the South of Germany in the WindForS complex terrain test field. The FSI is obtained by coupling the CFD URANS/DES code FLOWer and the multiphysi...
Conference Paper
Full-text available
View Video Presentation: https://doi.org/10.2514/6.2022-1334.vid Gust loads encountered during cruise flight induce critical loads to the aircraft structure. In this work the aerodynamic potential of different multifunctional Active Gust Load Alleviation (AGLA) concepts is assessed with the purpose to significantly reduce transient gust loads. The...
Conference Paper
In the present work, hybrid RANS/LES simulations of the NASA Common Research Model at the onset of stall are presented. The simulations were validated against experimental data from cryogenic measurements in the European Transonic Windtunnel within the European ESWIRP project. It was shown that the simulation setup is capable of reproducing the sta...
Preprint
Full-text available
This paper shows the results of CFD studies of turbulent flow fields and their effects on a wind turbine in complex terrain. As part of the WINSENT project a research test site comprising four meteorological masts and two research wind turbines is currently being constructed in the Swabian Alps in Southern Germany. This work is an essential part of...
Preprint
Full-text available
The behavior of a rooftop mounted generic H-rotor Darrieus vertical axis wind turbine (H-VAWT) is investigated numerically in realistic urban terrain. The interaction of the atmospheric boundary layer with the different buildings, topography, and vegetation present in the urban environment leads to the highly turbulent inflow conditions with contin...
Preprint
Full-text available
The influence of turbulent inflow, as it occurs in complex terrain, on the unsteady surface pressure distributions on a wind turbine is investigated numerically. A method is presented that enables an accurate reproduction of the inflow to the turbine in the complex terrain in Perdigao, Portugal. For this purpose, a precursor simulation with the ste...
Chapter
Full-text available
Gust loads on aircraft are critical for structural design. This paper investigates local bump-like modifications in the leading edge region on a generic supercritical airfoil at transonic inflow conditions for the purpose of gust load alleviation. Several parameters are studied to identify a sweet spot for gust load compensation. These include the...
Chapter
Unsteady CFD simulations of vertical “1-cos” gusts interacting with the DLR-F15 airfoil at transonic flow conditions are analyzed. The scope of the work is to assess the applicability of the simplified Disturbance Velocity Approach (DVA) for gust simulation, which is implemented in the CFD code TAU. While the DVA covers the interaction of the gust...
Chapter
In the present investigation, the unsteady flow field around a standstill offshore wind turbine is analysed in the hovering and approach regions of maintenance helicopters in order to identify critical flight regions. Three different inflow conditions are analysed, at the rated and cut-off wind speeds. One fictive hovering region and two fictive fl...
Chapter
Four different methods for the generation of input data for propeller models (Actuator Disk, Actuator Line) in CFD simulations are described and their results are compared with an unsteady fully resolved simulation of the propeller geometry. It is shown that the neglect of the rotation effects with a 2d method overestimates the propeller thrust and...
Chapter
This work describes the influence of the wind tunnel support system on the wake flow and associated forces acting on the CRM aircraft configuration in post-stall conditions at subsonic Mach numbers. Unsteady scale-resolving simulations at \(\alpha =18^{\circ }\), \(M_{\infty }=0.25\) and \(Re_{\infty } = 11.6\cdot 10^6\) were carried out using the...
Article
Full-text available
In the present study, the effects of the actuator line force smearing on the predicted near-wake development of a model wind turbine are evaluated. To exclude the uncertainties related to the blade loads computation, the loads of a corresponding blade-resolving simulation are imposed. Three force projection functions are applied, which all radially...
Article
Full-text available
Recent research developments have indicated that substantial reduction of both thefatigue and ultimate loads can be achieved by adopting trailing edge (TE) flap controlstrategies. Their aeroelastic tools employ blade element momentum (BEM) aerody-namic models enhanced with a sectional 2D treatment of the TE flap, neglecting the3D effect of the trai...
Article
Full-text available
The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplish...
Article
The present paper is intended to assess the ability of the state-of-the-art computational fluid dynamics (CFD) and blade element momentum (BEM) approaches for accurate load predictions on a 2.3 MW wind turbine rotor. Three different cases are considered, a steady uniform inflow condition, a turbulent uniform inflow condition and a turbulent inflow...
Article
Full-text available
The aeroelastic response of a 2 MW NM80 turbine with a rotor diameter of 80 m and interaction phenomena are investigated by the use of a high-fidelity model. A time-accurate unsteady fluid–structure interaction (FSI) coupling is used between a computational fluid dynamics (CFD) code for the aerodynamic response and a multi-body simulation (MBS) cod...
Conference Paper
Full-text available
Gust load analysis plays a substantial role in the certification process of aircraft. Active gust load alleviation techniques exhibit a high potential in significantly reducing the transient gust loads and thus the overall structural weight. In this paper, two dynamic actuator concepts are studied by means of CFD methods on a generic wing-fuselage...
Chapter
Full-text available
The effect of suction and oscillatory blowing (SaOB) on local flow separation in the slat cutout region downstream from a UHBR engine is investigated by means of URANS simulations. The simulation environment mirrors the wind tunnel test of an UHBR high-lift configuration conducted at the small scale low speed wind tunnel at Tel-Aviv University. The...
Conference Paper
This paper investigates active gust alleviation on a forward swept transport aircraft at transonic speeds. A gust study reveals a critical gust wave length of 50m leading to highest aerodynamic loads under cruise conditions. Gust induced separation is observed for particular cases. Deflection of a wing tip flap and aileron at the outer part of the...
Article
Full-text available
The disruptive potential of floating wind turbines has attracted the interest of both the industry and the scientific community. Lacking a rigid foundation, such machines are subject to large displacements whose impact on aerodynamic performance is not yet fully explored. In this work, the unsteady aerodynamic response to harmonic-surge motion of a...
Article
Gust response is one of the classic topics in aerodynamics. Two different transfer functions, Sears and Atassi, have been used to model the unsteady lift responses of an airfoil experiencing a sinusoidal gust over the past few decades. However, a significant discrepancy against measured data has consistently been observed. Although the discrepancy...
Article
Full-text available
A study of transonic buffet on the NASA Common Research Model at flight Reynolds numbers is presented. The ability of two different hybrid RANS/LES models as well as the URANS approach for resolving three-dimensional buffet motion was evaluated by means of spectral analysis. Automated Zonal DES and URANS simulations show similar results in terms of...
Article
Full-text available
In the present study, the performance of a small vertical axis wind turbine (VAWT) is investigated in realistic urban terrain, in presence of large buildings, hill and forested area. Normally, accelerated wind can be observed on the roof-top of the high-rise buildings. Thereby, different factors such as the orography, vegetation and presence of the...
Article
Full-text available
In the present study, prediction from high-fidelity Computational Fluid Dynamics (CFD) simulations of the tip vortex aging in the near-wake of a multi-MW wind turbine is evaluated and compared to in-situ measurements as well as results of a semi-empirical model. Optimized tip vortex refinement is also introduced to investigate the influence of the...
Article
Full-text available
Within the project “Windy Cities” the economic use of small wind turbines in urban areas is investigated in Tübingen, Germany. This test-site contains complex terrain, forested areas and various types of buildings making the local wind field more turbulent and complex. To avoid damages and reduced life times of small wind turbines caused by high tu...
Article
Full-text available
The current study describes analyses of the WINSENT wind energy test site located in complex terrain in Southern Germany by highly resolved numerical simulations. The resolved atmospheric turbulence is simulated with Delayed Detached Eddy Simulations by the flow solver FLOWer without consideration of the research wind turbines. The mean inflow and...
Article
Full-text available
Dynamic stall modeling remains one of the most difficult topic in wind turbine aerodynamics despite its long research effort in the past. In the present studies, comprehensive investigations involving CFD, engineering models and experimental data were performed within the joint collaborative work DSWind. Both static and dynamic characteristics of a...
Article
Full-text available
In cases with turbulent inflow, the analysis of the temporal development of forces could provide more insight into differences in calculated fatigue loads of wind turbines. While lifting-line-codes and the Blade-Element-Momentum (BEM) approach do not resolve the inflow, Computational Fluid-Dynamic (CFD) codes resolve the entire flow field. A compar...
Article
Full-text available
During the development process of wind turbines, there is a rising demand for detailed flow and multi-physics analyses. Especially the system level computational fluid dynamics (CFD), focusing not on a single component or aspect, but on the turbine as a system of geometric and dynamic properties can be used to improve the turbine quality and time t...
Article
Full-text available
RANS simulations of a generic ultra-high bypass ratio engine high-lift configuration were conducted in three different environments. The purpose of this study is to assess small scale tests in an atmospheric closed test section wind tunnel regarding transferability to large scale tests in an open-jet wind tunnel. Special emphasis was placed on the...
Article
Full-text available
Robust and accurate dynamic stall modeling remains one of the most difficult tasks in wind turbine load calculations despite its long research effort in the past. In the present paper, a new second-order dynamic stall model is developed with the main aim to model the higher harmonics of the vortex shedding while retaining its robustness for various...
Preprint
Full-text available
The disruptive potential of floating wind turbines has attracted the interest of both industry and scientific community. Lacking a rigid foundation, such machines are subject to large displacements whose impact on the aerodynamic performance is not yet fully acknowledged. In this work, the unsteady aerodynamic response to an harmonic surge motion o...
Article
Unsteady load calculations for a large wind turbine using two blade element momentum (BEM) codes (FAST, HAWC2) are compared with results from blade resolved computational fluid dynamics simulations (FLOWer). This is to assess the performance of BEM under varying turbulence levels. Instantaneous and mean of power, spectral data and sectional blade f...
Preprint
Full-text available
Abstract. Robust and accurate dynamic stall modeling remains one of the most difficult tasks in wind turbine load calculations despite its long research effort in the past. In the present paper, a new second order dynamic stall model is developed with the main aim to model the higher harmonics of the vortex shedding while retaining its robustness f...
Conference Paper
Full-text available
The close coupling of the ultra-high bypass ratio (UHBR) engine on a modern airliner poses a challenging task. The large engine nacelle diameter and a close coupling to the wing require slat cutouts. In the attempt to remedy for the maximum lift loss, the Active Flow Control (AFC) is employed. The effect of steady suction and oscillatory blowing on...
Preprint
Full-text available
Abstract. The aero-elastic response of the DANAERO wind turbine and interaction phenomena are investigated by the use of a high-fidelity model. A time-accurate unsteady fluid-structure interaction (FSI) coupling between a computational fluid dynamics (CFD) code for the aerodynamic response and a multi-body simulation (MBS) code for the structural r...
Conference Paper
Full-text available
This paper investigates different concepts for active gust alleviation (GLA) on a generic transport aircraft configuration at transonic speed by means of viscous and inviscid CFD simulations. Four types of dynamic actuator concepts are presented including a fuselage flap, a wing tip flap, a trailing edge flap and a leading edge flap. The wing tip f...
Chapter
Hybrid RANS/LES simulations of the flow around the NASA Common Research Model aircraft configuration were carried out with the focus on understanding the interaction of the separated wake with the tailplane in the presence of massively separated flow on the main wing. Validation of the CFD data using PIV data obtained for the flow conditions at \(\...
Chapter
There are different methods to simulate aircraft propellers with different degrees of approximation. In this study, a boundary condition based Actuator Line (ACL) method is presented for parametrized and fast unsteady propeller calculation. In order to validate the ACL, comparisons are made with experimental data, the results of an Actuator Disk (A...
Chapter
Full-text available
Simulations of near zero pressure gradient turbulent boundary layer interacting with Suction and Oscillatory Blowing (SaOB) were conducted using URANS equations. Different blowing velocity Boundary Conditions (BC) and spatial resolutions were investigated with the effort to reproduce the hot-wire measurements on the flat plate and thus pave the way...
Chapter
Full-text available
The results of two different numerical techniques, Unsteady Reynolds Averaged Navier Stokes and Delayed Detached Eddy Simulation, are compared to determine their accuracy in the prediction of aerodynamic and aeroacoustic performance of Darrieus vertical axis wind turbines. The flux for URANS simulations is computed using the central differencing sc...