Impact of Shape Change on Capsule Aerodynamics and Shock-wave Boundary Layer Interaction

Blunt capsule shapes have proven to be suitable for atmospheric entry flights on numerous missions. Some concepts like MarcoPolo-R focus on fully passive entry systems without a parachute, demanding for aerodynamic stability of the shape throughout the complete entry flight. These probes are commonly equipped with a Thermal Protection System (TPS) consisting of an ablative material. The recession of the TPS in the early entry flight phase may lead to a significant shape change. The capsule needs to remain aerodynamically stable for a successful mission completion despite these shape changes. Within ESA’s Modshape TRP the aerodynamic impact of the recession on the MarcoPolo-R capsule is investigated experimentally and numerically. Static force and moment measurements in the TMK wind tunnel are a major part of this TRP. The experimental simulations are conducted on the nominal or baseline configuration and two configurations representing the aero shape with the recessed TPS after the hot entry flight phase of different entry scenarios. The flow structure around the capsule is visualised at supersonic Mach numbers by means of schlieren imaging. Under certain conditions, development of a complex shock system on the leeward side of the inclined capsule is observed. Numerical simulations with the DLR TAU code are performed to support the interpretation of the flow phenomena in these cases

Capsule aerodynamics and shock-wave boundary layer interaction (SBLI) in supersonic and transonic flow

Static force and moment measurements are performed on the MarcoPolo-R aero shape in the trisonic wind tunnel TMK. The static stability behaviour of the capsule is characterized in the Mach number range 0.5<= M<= 3.5 reproducing the Mach and Reynolds conditions of the flight trajectory in the supersonic regime. An aerodynamic database is built based on the experimental results. The flow structure around the capsule is visualised in supersonic tests by means of schlieren imaging. Under certain conditions, development of a complex shock system on the leeward side of the inclined capsule is observed. Oil film technique is used to visualise boundary layer phenomena in connection to this shock system. Numerical simulations with the DLR TAU code are performed to support the interpretation of the flow phenomena under these conditions

EFESTO-2: European Flexible Heat Shields Advanced TPS Design and Tests for Future In-Orbit Demonstration - 2

EFESTO-2 is an EU-funded project under Horizon Europe that aims to enhance European expertise in Inflatable Heat Shields (IHS). Building on the achievements of the previous EFESTO project (H2020 funds No 821801), EFESTO-2 focuses on advancing key IHS technologies to increase their Technology Readiness Level (TRL). The project pillars include analyzing the business case for IHS applications, exploring additional aspects of IHS, improving tools and models, and establishing a development roadmap for IHS systems. This paper outlines the project objectives and plan, highlighting ongoing and future activities for the next two years, positioning it within the European re-entry technology roadmap. Funding was provided by the European Union's Horizon Europe program (grant agreement No 1010811041)

EFESTO‑2: European Flexible Heat Shields Advanced TPS Design and Tests for Future In‑Orbit Demonstration‑2

EFESTO-2 is an EU-funded project under Horizon Europe that aims to enhance European expertise in Inflatable Heat Shields (IHS). Building on the achievements of the previous EFESTO project (H2020 funds No 821801), EFESTO-2 focuses on advancing key IHS technologies to increase their Technology Readiness Level (TRL). The project pillars include analysing the business case for IHS applications, exploring additional aspects of IHS, improving tools and models and establishing a development roadmap for IHS systems. This paper outlines the project objectives and plan, highlighting ongoing and future activities for the next 2 years, positioning it within the European re-entry technology roadmap. This project has received funding from the European Union's Horizon Europe program (grant agreement No 1010811041)

Verdichtungsstoßvisualisierung mittels Laserlichtschnitt

Bei der Entwicklung von transsonischen Verdichterbeschaufelungen werden laseroptische Untersuchungen der internen Turbomaschinenströmung durchgeführt. Der optische Zugang zur Messstrecke ist dabei meist durch die Gehäusegeometrie derart beschränkt, dass für die Ermittlung der lokalen Strömungsgeschwindigkeiten nur punktförmige Messverfahren eingesetzt werden können. Dadurch sind die Untersuchungen relativ zeitintensiv. Auch die Kenntnis über die Lage der Verdichtungsstöße stellt eine quantitative Information dar. In der vorliegenden Arbeit wird deshalb ein Messverfahren beschrieben, mit dem Verdichtungsstöße in transsonischen Strömungen mit Hilfe eines Laserlichtschnitts und in der Strömung befindlichen Partikeln sichtbar gemacht werden können. Das flächige Verfahren ist auch bei beschränkter optischer Zugänglichkeit einsetzbar und liefert nach vergleichsweise kurzer Messdauer die vollständige dreidimensionale Stoßkonfiguration. Die Leistungsfähigkeit des Verfahrens wird durch Vermessung einer 3D-Keilströmung im Windkanal und Ermittlung der Stoßkonfiguration in einem transsonisch angeströmten Profilgitter demonstriert. Die Messergebnisse stimmen dabei gut mit den Ergebnissen anderer Verfahren und der numerischen Simulationsrechnungen überein

Untersuchungen zur Schubstrahlinteraktion an einem Unterschallflugkörper mit Hilfe von Pressure-Sensitive-Paint

Im Rahmen des Projektes Flugkörpertechnologien 2020+ wurde die Interaktion der Schubstrahlen mit den Steuerflächen der Leitkonfiguration 6 untersucht. Dafür wurde ein Kaltgasmodell für die Vertikale Messstrecke Köln über Ähnlichkeitskennzahlen ausgelegt und experimentell untersucht. Mit Hilfe der Schlierentechnik und Pressure-Sensitive-Paint konnte die Struktur der Schubstrahlen und die resultierende Oberflächendruckverteilung für unterschiedliche Strömungs- und Schubzustände sichtbar gemacht werden. Es wurden neutral angestellte Finnen untersucht und eine durch die Schubstrahlen veränderte Druckverteilung festgestellt. Übertragen auf ausgeschlagene Finnen wird mit einer leicht reduzierten Ruderwirkung gerechnet

Experimental Study on the Dynamic Stability of the IXV Configuration

Dynamic stability of the IXV configuration has been investigated using free oscillation measurement technique in the Trisonic Windtunnel (TMK). In the transonic Mach number range an escalating behavior of the pitching moment damping derivative has been observed, although the vehicle is statically stable. At Mach 0.8 the vehicle showed the most unstable behavior. The instability becomes weaker with increasing Mach number. At Mach number 1.1 the vehicle is only slightly instable. In the supersonic regime experimental data showed an excellent repeatability. All supersonic tests provided a negative pitching moment damping coefficient, i.e. dynamically stable vehicle behavior

Tracer based Shock Visualisation A new measurement technique

Knowledge of the shock wave position is quantitative information which helps in gathering and understanding the character of transonic and supersonic flows. Therefore visualisation techniques such as the Schlieren method or holographic interferometry are applied to wind tunnel experiments where the structure of the flow field is essentially two dimensional. In this report a recently developed non-intrusive technique to analyse three dimensional shock configurations without the need of velocity measurements is introduced. Thereby, the optical set-up allows the application of the technique to test sections with restricted optical access, e.g. to transonic compressors with a complex geometry of the casings. Up to now, only point-wise measurement techniques have been used to analyse the air flow velocities inside of those machines. The shock wave generates an considerable increase in the density of the flow. If particles are added upstream of the shock, it can be assumed that the concentration of the particles increases nearly in the same way. To visualise this, a laser light sheet is brought into the test section and illuminates the particles. the scattered light is captured by a CCD camera so that the position of the shock wave can be determined. To analyse the three dimensional structure of a shock wave, the light sheet is moved perpendicular to the flow direction. This new measurement technique (called Tracer based Shock Visualisation, TSV) is applied ot both, a supersonic wedge flow at Ma = 2.43 and a more complex shock wave configuration in a transonic cascade flow at Ma = 1-09. The gathered results are conclusive with Schlieren photographs, numerical simulations and, in case of the casdade flow, also with the simultaneously recorded surface pressure distribution. The applicability of the measurement technique to a rotating compressor is discussed. The problem with those measurements is not only the restricted optical access but also the synchronization of the image capturing process wih´th the rotational speed of the rotor. Both problems have been covered within the development of the TSV technique

Experimental Study on Static and Dynamic Stability of a Blunt Body Configuration

The aero shape of ESA’s Intermediate eXperimental Vehicle (IXV) is prone to suffer from stability problems in the transonic regime. To avoid a supersonic descent system, small fins are implemented to the shape with the aim of passing the transonic flight regime at angles of incidence below 40° and improve static stability conditions in subsonic with a lift-to-drag ratio higher than 1. The fin shape is optimised in a numerical pre-study and two new configurations are investigated experimentally in the Trisonic Wind tunnel TMK of DLR Köln. Static and dynamic aerodynamic coefficients are determined between Ma=0.5 and 2.0 and implemented in an AEDB. The configurations’ performance is compared to that of the original IXV aero shape. It can be stated, that implementation of the fins significantly improved the longitudinal static and dynamic stability of the aero shape. The authors therefore recommend further investigations on the new configurations

Numerical Investigation of Wind Tunnel Tests to Measure Dynamic Stability

Lifting body type reentry vehicles like the Intermediate Experimental Vehicle (IXV) tend to be aerodynamically unstable in the tran- and subsonic flight regime. To determine the dynamic behaviour of the vehicle the free oscillation technique is used. Numerical simulations of corresponding wind tunnel tests have been carried out by coupling the solvers for the outer flow and the vehicle motion. For the considered test conditions in super-, tran-, and subsonic flow simulations and experiments show dynamically stable behaviou