Thomas Streit

Thomas Streit
German Aerospace Center (DLR) | DLR · Institute of Aerodynamics and Flow Technology

About

74
Publications
7,692
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402
Citations
Citations since 2017
11 Research Items
164 Citations
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060

Publications

Publications (74)
Conference Paper
Results for the numerical aerodynamic design and analysis of a long-range, large passenger aircraft equipped with a Hybrid Laminar Flow Control (HLFC) system are presented. This work was performed within the European project HLFC-WIN. The reference geometry of this study is the long-range cruise Airbus research XRF1 geometry, designed for turbulent...
Conference Paper
This paper presents the aerodynamic performance analysis of realistic large passenger aircraft equipped with a Hybrid Laminar Flow Control (HLFC) system. To this purpose, the design of two HLFC aircraft geometries is first outlined, both designed by DLR based on an Airbus HLFC variant of the XRF-1 geometry. Numerical simulations were performed with...
Conference Paper
This work elaborates the investigation of a long-range transport configuration with hybrid laminar flow control (HLFC) using an iterative pre-design process featuring loads analysis and structural optimization. The HLFC wing was designed with a 3D transonic inverse method. From the loads perspective, the main changes compared to the turbulent count...
Chapter
This work presents results of a numerical feasibility study in which HLFC wing designs for a wind tunnel model were obtained for a test in the S1MA wind tunnel. The wind tunnel model will be a testbed for HLFC technology in general and specifically a test of the integrated HLFC technology in the ground-based demonstrator of the European project HLF...
Conference Paper
Full-text available
This paper investigates active gust alleviation on a forward swept transport aircraft attransonic speeds. A gust study reveals a critical gust wave length of 50m leading to highestaerodynamic loads under cruise conditions. Gust induced separation is observed for particularcases. Deflection of a wing tip flap and aileron at the outer part of the win...
Conference Paper
Full-text available
The paper describes and analyses potential concepts for gust alleviation at transonic speeds applied on a forward swept transport aircraft configuration. The main objective is to reduce structural weight by minimizing gust induced loads. Both inviscid and viscous aerodynamic simulations are performed for analysis. A gust study reveals a critical gu...
Conference Paper
In this work we present analysis and design results of NLF airfoils and wings for long range aircraft. Extension of wing laminar boundary layer for long range transonic aircraft design is limited by large Reynolds numbers and large wing leading edge sweeps. To explore the NLF potential different swept tapered 2.75D airfoils were designed using the...
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...
Article
Full-text available
The Temperature-Sensitive Paint (TSP) method is used for surface-based flow visualizations on a swept-wing wind-tunnel model with a generic natural laminar-flow airfoil. Within the investigated parameter range the stationary crossflow instability is the dominating instability mechanism. Based on the TSP results the location of the laminar-turbulent...
Conference Paper
The challenge of increasing range and speed of a rotorcraft is encountered in the scope of the European CleanSky2 “Fast Rotorcraft” project by Airbus Helicopters with the compound helicopter design RACER (RapidAndCostEfficientRotorcraft) for which the box wing and the tail parts designs are respectively protected by patent. This paper presents the...
Article
The DLR inverse design code computes the wing geometry for a prescribed target pressure distribution. It is based on the numerical solution of the integral inverse transonic small perturbation (TSP) equations. In this work, several extensions and modifications of the inverse design code are described. Results are validated with corresponding redesi...
Conference Paper
In recent years the DLR inverse design code has often been used to design wings for transonic transport aircraft. The DLR inverse design code computes the wing geometry for a prescribed target pressure distribution. It is based on the numerical solution of the integral inverse transonic small perturbation (TSP) equations. New applications and confi...
Article
Es wird die Erweiterung des inversen Entwurfsverfahrens auf Randbedingungen mit 2 Symmetrieebenen vorgestellt. Dies ermöglicht den Entwurf von Flügeln für Windkanalumgebungen. Die bisherige Variante dieses Entwurfsverfahrens entwirft im symmetrischen Fall unter Zuhilfenahme von einer Symmetrieebene nur eine Flügelhälfte. Der ursprüngliche inverse E...
Article
In the present work natural laminar flow (NLF) and hybrid laminar flow (HLF) wing designs are presented which were obtained by combining new methodologies with experience and knowledge obtained with traditional laminar wing design methods. The NLF wing design is performed for wing-body configurations with backward swept wing (BSW) and forward swept...
Conference Paper
In the present work natural laminar flow (NLF) and hybrid laminar flow (HLF) wing designs are presented which were obtained by combining new methodologies with experience and knowledge obtained with traditional laminar wing design methods. The NLF wing design is performed for wing-body configurations with backward swept wing (BSW) and forward swept...
Conference Paper
The present work reports on the progress recently made in methodologies for robust laminar wing design. Here robustness means reserves in the design that allow for acceptable off-design performance qualities by keeping the wing laminar over a wide range of flight conditions. This is achieved by combining new methodologies with experience and knowle...
Chapter
In this work airfoil and wing design results using a sectional conical wing method for analysis and design are presented. This method allows the design of swept tapered wing sections. It is useful for transonic Natural Laminar Flow (NLF) design, where sweep and tapering of the wing has to be taken into account. In the first part of this work a tran...
Article
In this work airfoil and wing design results using a sectional conical wing method for analysis and design are presented. This method allows the design of swept tapered wing sections. It is useful for transonic Natural Laminar Flow (NLF) design, where sweep and tapering of the wing has to be taken into account. In the first part of this work a tran...
Conference Paper
In this work airfoil and wing design results using a sectional conical wing method for analysis and design are presented. This method allows the design of swept tapered wing sections. It is useful for transonic NLF design, where sweep and tapering of the wing has to be taken into account. In the first part of this work a transonic tapered wing NLF...
Conference Paper
In einem multidisziplinären Ansatz wird im Rahmen des DLR-Projektes LamAiR ein aerodynamisch optimier-tes und in Grenzen ein systemtechnisch optimiertes Seitenleitwerk eines Airbus A320 numerisch für die Um-setzung der Hybrid-Laminarhaltung ausgelegt. Die aerodynamische Entwurfsaufgabe soll folgenden wesent-lichen Anforderungen gerecht werden: a....
Conference Paper
A multi-fidelity system of computer codes for the analysis and design of vehicles having extensive areas of laminar flow is under development at the NASA Langley Research Center. The overall approach consists of the loose coupling of a flow solver, a transition prediction method and a design module using shell scripts, along with interface modules...
Conference Paper
In this work a method based on sectional conical wings is presented which allows the analysis and design of airfoil sections for swept tapered wings with a computational effort which is slightly higher than a 2D computation. Navier-Stokes analysis and re-design examples using the sectional conical wing approximation are given. They show that pressu...
Conference Paper
Full-text available
Within the European Project Telfona the Pathfinder Model was designed, analyzed numerically, constructed and tested with the aim of obtaining a laminar flow testing capability in the European Transonic Wind Tunnel (ETW). The model was designed for natural laminar flow (NLF) for transonic flow conditions with high Reynolds number. Results of pre-tes...
Conference Paper
Full-text available
A wind-tunnel experiment on laminar-turbulent transition has been performed in ETW at high Reynolds number and cryogenic conditions. The studied geometry is a swept-wing configuration. The transition location was determined by means of Temperature Sensitive Paint (TSP). The experimental observations were further analysed using different transition...
Conference Paper
Summary The induced drag of non-planar wings is compared to that of planar wings which result from unfolding the non-planar ones. It is shown that due to the induced lift, there exist non-planar configurations with positive span camber that have an overall aerodynamic performance increase in comparison to the planar ones. The induced lift and incr...
Conference Paper
Full-text available
The Pathfinder model was designed in the course of the TELFONA European Research Project as a calibration tool to evaluate the transonic, cryogenic ETW facility for laminar flow testing, and assess the possibility for studies of NLF or HLF wings in ETW. The Pathfinder wing is a simplified, low taper, swept wing with an optimized profile allowing al...
Article
This paper describes the aerodynamic performance of three different forward swept wing (FWS) designs with natural laminar flow (NLF), in which were studied in the EU FP6 Integrated Programme NACRE (New Aircraft Concepts REsearch). The first design is the baseline geometry while the other two are optimised designs obtained by DLR and ONERA based on...
Conference Paper
Full-text available
With the goal of studying Natural Laminar Flow (NLF) wings for future ‘green’ transport aircraft, the aim of the European Research Project TELFONA is to develop and demonstrate the possibility of testing full aircraft models at large Reynolds numbers in the cryogenic Wind Tunnel ETW, with direct measurements of total drag. Two main steps were defin...
Conference Paper
Full-text available
Within the European Project Telfona the Pathfinder Model was designed, analyzed numerically, constructed and tested with the aim to obtain the capability of laminar flow testing of the European Transonic Wind Tunnel (ETW). The model was designed for natural laminar flow (NLF) for transonic flow conditions with high Reynolds number. Pre-test numeric...
Chapter
Increasing fuel costs and environmental burden in particular with respect to the CO2 emissions require a substantial improvement of efficiency of transport aircraft. In the past a multiplicity of improvements in aircraft development has been carried out. In a historical overview the most important ones are briefly described. Different aerodynamic t...
Conference Paper
Lifting line and Euler techniques have indicated that an elliptical planform cambered in the spanwise direction appears to have a lower induced drag than the uncambered, planar configuration, when both of then have identical arc lengths and the same wetted areas. In other words, a wing geometry with a lower projected span than the planar wing, only...
Conference Paper
A wind-tunnel experiment on laminar-turbulent transition has been performed in ETW at high Reynolds number and cryogenic conditions. The studied geometry is a swept-wing configuration. The transition location was determined by means of Temperature Sensitive Paint (TSP). The experimental observations were further analysed using different transition...
Conference Paper
This paper concerns the aero-structural design of winglets for transport aircrafts. The different multidisciplinary design targets are discussed and limitations of the conventionally aerodynamics-focused design approach are shown. In order to better combine conflictive targets the design space is opened towards advanced passive and active structura...
Article
This paper concerns the aero-structural design of winglets for transport aircrafts. The different multidisciplinary design targets are discussed and limitations of the conventionally aerodynamics-focused design approach are shown. In order to better combine conflictive targets the design space is opened towards advanced passive and active structura...
Conference Paper
In this work retrofit winglets are designed for a transonic aircraft. The used geometry is a generic twin engine aircraft. In a first step winglets are designed using a lifting line method along with RANS solutions. L/D is optimized by taking into account a certain wing root bending moment reserve for the reference wing. The final analysis includes...
Article
A design study of wing tip devices at high and low speeds is described. The basis of the design study is an equivalent drag approach containing both aerodynamic drag gain and structural weight penalty. A comprehensive parameter study is carried out using a rapid aerodynamic prediction tool named Lift and Drag Component Analysis (LIDCA). Adding to a...
Article
Pressure distribution analysis is given for the M-DAW low speed wind tunnel tests with the model XO3D1. Low speeds were performed in the KKK-DNW (July 2003) with the reference tip devices and in the ETW (November 2005) using the novel downward pointed winglet and the Küchemann tip. For the low speed ETW take-off configuration tests, results are com...
Article
Full-text available
A transonic multi-lifting surface design method and the corresponding codes are further developed to improve the convergence character in higher Mach number cases at transonic flow. It is coupled with the DLR RANS solver TAU and the mesh generatotr CENTAUR to design canard-wing configurations and a blended wing body. The results show that the conve...
Article
Full-text available
An aerodynamic design method and corresponding codes are developed for three dimensional multi-lifting surfaces at transonic flow. It is based on the “iterative residual correction” concept that is successfully used for transonic wing design and subsonic multi-lifting surface design. The up wind scheme is introduced into governing equations of mult...
Conference Paper
Full-text available
An assessment study of wing tip devices at low speed is described. Designed at cruise, the device provides poor low speed performance due to large regions of flow separation. Both airfoil redesign and the usage of moving parts on the leading edge are investigated to gain the flow behaviour. This study was done in two stages using a clean configurat...
Article
A parametric analysis of several types of rigid winglet geometries was cariied out at cruise condition using a rapid databased aerodynamic prediction method. The optimised configurations were obtained according to an effective drag approach, which takes into account aerodynamic improvements and structural penalties. The most promising device found...
Conference Paper
An aerodynamic design method and corresponding codes have been developed for three dimensional multi-lifting surfaces at transonic flow. It is based on the "iterative residual coreection" concept that is succesfully used for transonic wing and subsonic multi-lifting surface design. An upwind scheme is introduced into the governing equations for the...
Article
Im Rahmen einer Auftragsarbeit der Firma REPOWER wurden die aerodynamischen Eigenschaften des Profils der PP77 Windkraftanlage (beim Radius 5m - Profil PP77R5) und einer Modifkation berechnet. Die Vermutung, dass das bislang verwendete Profil Abtrieb erzeugt, konnte klar bestätigt werden. Auch, dass die Modifikation einen deutlichen Auftriebsgewinn...
Article
This report presents RANS CFD solutions obtainend in WP2 Phase II. Results obtained in Phase I are summarized and completed. Solutions were obtained for the N-47 model for high speed and the corresponding XO3d take-off configuration for low speed with three different wing tip devices: Küchemann tip (basic configuration), fence tip and large winglet...
Article
Blind RANS CFD solutions were obtained for the N-47 wing body with three different wing tip devices: Küchemann tip (basic configuration), fence tip and large winglet. Onflow conditions are M=0.85 and a high Reynolds number Re=54.2 mill, corresponding to cruise conditions. Solutions were obtained on unstructured hybrid meshes using the TAU solver. S...
Article
Wake analysis of PIV data obtained in the DNW-KKK wind tunnel measurement with the X03D low speed take off configuration with different wing tip devices. The topology, strength, extension and position of the tip vortices is compared among the different wing tip devices for different incidences and Reynolds numbers. The unsteadiness of the measureme...
Conference Paper
Numerical solutions of the Navier-Stokes equations for a modern transport configuration with three different wing tip devices are presented. Solutions are obtained at high speed for the cruise configuration and at low speed for the corresponding take-off configuration. This study is performed within the European Union project M-DAW (Modelling and D...
Conference Paper
A design study of wing tip devices at high and low speeds is described. The basis of the design study is an equivalent drag approach containing both aerodynamic drag gain and structural weight penalty. A comprehensive parameter study is carried out using a rapid databased aerodynamic prediction tool named Lift and Drag Component Analysis (LIDCA). D...
Article
A transonic multi-lifting surface design method coupled with CFD tools and programs is used for the design of a canard/wing configuration. The aerodynamic design method for a single lifting surface based upon the iterative residual correction principle is developed for designing mult-lifting surfaces, an aerodynamic design code based on this method...
Conference Paper
Full-text available
Im Rahmen des Technologievorhabens Pro-HMS wird ein Flügel mit multifunktionalen Steuerflächen entwickelt. Da das multifunktionale Steuerflächensystem alle Phasen einer Flugmission einschließlich der Manöver- und Böenfälle beeinflusst, ist eine interdisziplinäre Vorgehensweise erforderlich. Auf Basis eines typischen Anforderungsprofils für ein Flug...
Article
In diesem Bericht werden die Low Speed Arbeiten des DLR zum AP 5.1 des interdisziplinären Forschungsvorhaben ProHMS (Prozesskette Hochauftrieb mit Multifunktionalen Steuerflächen) zusammengefasst. Das Arbeitspaket AP 5.1 ist der Entwurf und Parameterstudie an Mini-TED's (Mini-Trailing Edge Devices). Das AP 5.1 besteht aus drei Arbeitspunkten: 1. Er...
Article
Im Rahmen des Technologievorhabens Pro-HMS wird ein Flügel mit multifunktionalen Steuerflächen entwickelt. Da das multifunktionale Steuerflächensystem alle Phasen einer Flugmission einschließlich der Manöver- und Böenfälle beeinflusst, ist eine interdisziplinäre Vorgehensweise erforderlich. Auf Basis eines typischen Anforderungsprofils für ein Flug...
Article
In diesem Bericht werden Ergebnisse aerodynamischer Nachrechnungen an Flügel-Rumpf-Konfigurationen der Envoy 7 der Fa. Fairchild Dornier mit verschiedenen Flügelseitenkanten-Erweiterungen vorgestellt. Im Vergleich zum 728JET ist die Envoy 7 für größere Reichweiten ausgelegt, die durch entsprechende Flügelmodifikationen im Seitenkantenbereich, mit s...
Conference Paper
In this paper the activities of the Institute of Design Aerodynamics within the DLR project "Dreiflächen-Flugzeug (3FF)" - Three-Surface Aircraft, TSA - concerning the investigation of three-surface aircraft configurations are presented. Results of aircraft predesign calculations of the retrofitted wind-tunnel model DLR-F11 show higher performances...
Article
In diesem Bericht wurden Ergebnisse präsentiert, in denen verschiedene Flügel- und Flügel-Rumpf-Konfigurationen für das transsonische Verkehrsflugzeug DO-728 (70 Sitzer), bzw. DO-928 (90 Sitzer) der Firma Fairchild-Dornier nachgerechnet und entworfen wurden. Entwurfsziel war, bei vorgegebenen Geometrieanforderungen und bei vorgegebenen Auftriebsbei...
Conference Paper
In this paper the activities of the Institute of Design Aerodynamics within the DLR project "Dreiflächen-Flugzeug (3FF)" - Three-Surface Aircraft, TSA - concerning the investigation of three-surface aircraft configurations are presented. First aircraft predesign results indicate a better performance for TSA configurations compared with conventional...
Chapter
Using conventional design methods a laminar wing was designed for the DO 328 commuter airplane in a preceding work. However, in the vicinity of the body and the nacelle, strong interference effects diminished the extent of laminar flow. In this work a 3D design method based on the solution of the Euler equations was used to enlarge the extent of la...
Conference Paper
For the design of hypersonic configurations heat transfer plays an essential role. At high velocities high temperature effects have to be taken into account, since a perfect gas assumption for air leads to major errors concerning the calculation of temperature and heat transfer. In the present paper the application of surface inclination methods an...
Article
For the design of hypersonic configurations heat transfer plays an essential role. At high velocities high-temperature effects have to be taken into account; here a perfect gas assumtion for air leads to major errors concerning the calculation of temperature and heat transfer. Therefore in this work the DLR design tool HOTSOSE is extended to applic...
Article
The numerical solution of the Euler and Navier-Stokes system of equations and experimental data for the supersonic flow around a complex missile configuration are compared. The Euler and Navier-Stokes equations are solved with the DLR finite-volume method CEVCATS using multiblock mesh structure and multigrid acceleration technique. The numerical so...
Article
In the design of an hypersonic configuration heat-transfer plays an essential role. For computations within aerothermal predesign fast and sufficiently accurate heat prediction methods are required. In this work approximate methods for computing skin friction and heat transfer for hypersonic flow have been studied. The evaluation of heat transfer a...
Article
We have implemented and tested a method to eliminate critical slowing down from Monte Carlo (and possibly other) simulations of very large systems, even for a ``critical'' state, where the correlation length of fluctuations is the size of the sample. Static correlation functions on all length scales (down to microscopic!) may thus be obtained with...
Article
An N-orbital model is considered for a two-dimensional disordered system in a strong perpendicular magnetic field. The Hamiltonian is projected on the lowest Landau level. In a field theoretical formulation the large N limit result corresponds to the translationally invariant saddle point for this model. A diagrammatic expansion in powers of 1/N is...
Article
We study the critical properties of an Ising model with nearest neighbor antiferromagnetic interactions, placed on a triangular lattice, where each site is occupied by a spin, only with x probability. Randomness and frustration, two essential ingredients of spin‐glasses, are present in this model. The entropy is obtained, by a transfer matrix calcu...
Article
We study an Ising model with nearest-neighbor antiferromagnetic interactions. It is placed on a triangular lattice, where each site is occupied by a spin with x probability. There is no applied magnetic field. Randomness and frustration, two essential ingredients of spin-glasses, are present in this model. We study its critical properties here. The...
Article
We perform a Monte Carlo simulation of systems of N spins randomly located on an fcc lattice with an atomic concentration of 0.5% and interacting via a Ruderman-Kittel-Kasuya-Yoshida exchange. Our interest lies on the character of the paramagnetic—to—spin-glass transition. We evaluate the time-dependent equilibrium correlation function χSG(t)=N-1Σi...

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