Dominik Neeb

Preliminary Aerodynamic Shape Optimization of the SpaceLiner by Means of Engineering Methods

An optimization routine has been implemented, validated and applied to improve the outer shape design of the DLR proposed SpaceLiner concept with engineering based aerodynamic tools including the estimation of aerothermodynamic loads. The routine consists of an aerodynamic approximation module based on Newtonian and additional engineering methods, a shape parameterization module to modify and mesh the geometry, and an optimization module based on a single-objective response surface methodology. The routine’s single components and the complete loop have been validated and tested to study their sensitivities. The optimization routine has been applied first to single components of the SpaceLiner to study sensitivities and influences of specific design parameters. Based on these studies the tool has been applied to the complete vehicle considering different flight conditions of a reference trajectory. The resulting shapes are evaluated for their longitudinal trim performance. An improvement in aerodynamic performance can be achieved especially in the hypersonic flow regime, which represents the major part of the trajectory.

Instrumentation of the SHEFEX-II Flight Experiment and Selected Flight Data

The SHEFEX-II hypersonic flight experiment was launched from Andoya rocket range in Norway on 22.06.2012 consisting of an extensively instrumented scientific payload on top of a two-stage rocket configuration. With an apogee of about 177 km, the vehicle achieved flight velocities up to 2790 m/s corresponding to Mach numbers up to 9.3. Almost all heat flux, temperature and pressure sensors provided very clear data during ascent and descent phases. Measured pressure data from sensors at different locations of the scientific payload show consistent results concerning the aerodynamic behavior on the vehicle along the complete trajectory. Pressure fluctuations measured during ascent, show a good correlation to angle of attack variations. Calculated pressure coefficients from a CFD analysis at selected trajectory points are in good agreement with the measured pressure data.

Aerothermal Postflight Analysis of the Sharp Edge Flight Experiment-II

The aerothermal instrumentation of the Sharp Edge Hypersonic Flight Experiment SHEFEX-II, which was launched from Andoya Rocket Range on top of a two-stage rocket configuration, provided very useful flight data. Complementary to the pressure data, heat flux rate and surface temperature were measured at selected locations on the payload along the complete ascent and descent trajectory. Measured heat flux rate and pressure fluctuations show excellent correlation with angle-of-attack variations. Calculated heat flux evolution using a hypersonic boundary-layer code along the trajectory is in reasonable agreement with measured heat flux data during flight. Boundary-layer transition was measured at a boundary-layer edge Reynolds number of approximately 3·106 for both ascent and descent phases. The complementary analytical and numerical study for the flight rebuilding at selected flight points provided very useful data and allowed better understanding of the physical phenomena. Finally, a combined analytical–num...

Rough-Wall Heat Flux Augmentation Analysis Within the ExoMars Project

Surface roughness, especially if enhanced due to ablative form change, increases skin friction drag and convective heat transfer over reentry vehicles. Although the corresponding heat flux augmentation is usually lower compared to increased friction, careful consideration in the prediction of the resulting heat load levels is required. Within the European Mars mission ExoMars, the potential roughness impact on the thermal protection system of the descent module has been analyzed based on analytical predictions, numerical calculations, and dedicated experimental campaigns. This paper describes the experimental efforts in the compressible flow regime to study the impact of roughness at representative conditions. The data are discussed based on comparisons with prediction methods and results of other investigators. Based on these data, the numerical predictive capabilities within the ExoMars program are characterized and validated.

Rough wall heat flux augmentation analysis in the Framework of the ExoMars project

Surface roughness, especially if enhanced due to ablative form change, increases skin friction drag and convective heat transfer over re-entry vehicles. Although the corresponding heat flux augmentation is usually lower compared to increased friction, careful consideration in the prediction of the resulting heat load levels is required. Within the European Mars mission ExoMars, the potential roughness impact on the thermal protection system of the descent module has been analyzed based on analytical predictions, numerical calculations and dedicated experimental campaigns. This paper describes the experimental efforts in the compressible flow regime to study the impact of roughness at representative conditions. The data is discussed based on comparisons with prediction methods and results of other investigators. Based on this data the numerical predictive capabilities within the ExoMars program is characterized and validated.