ResearchProject Area B
Subproject B3

Subproject B3 Loss Behavior of Complex Surface Structures

In subproject B3 complex surface structures, influenced by operation and regeneration, are optically measured, characterized and parameterized. Representative structures have been selected to analyze the interaction between near wall flow and complex surface structures. This interaction is analyzed both numerically with Large-Eddy-Simulation and  experimentally in a flow channel with Particle Image Velocimetry. Additionally, the influence of complex surface structures on integral aerodynamic loss behavior of compressor blades is determined by measures of the profile pressure distribution and the wake.

MOTIVATION AND OBJECTIVES

Surface structures on a used turbine blade from a real aircraft engine

The flow prediction of integral and local impact of complex roughness on the blading with established Reynolds-Averaged Navier-Stokes (RANS)-Methods is currently limited. In power plant parts, the quantitative impact of complex roughness is determined by manifold,  multi-modal aerodynamic boundary conditions and effects that interact with each other. Thus, roughness affects the condition of laminar, transitional and turbulent boundary layers. The objective of sub-project B3 is to model a RANS-based description of the local roughness impact on flow boundary layers, and hence predict accurate the impact of complex roughness on the aerodynamic losses, as well as the work loading of compressors and turbines. Based on the knowledge and data of the first two funding periods, the work package includes the development of a turbulence- and transition-model with its modeling, calibration and validation.

RESULTS

In the first two SFB funding periods, the impact of complex roughness on the flow of blading and near wall sections could be quantified experimentally and numerically. The reason behind the limited comparability of the results with established RANS-methods was identified as insufficient representation of small-scale turbulent structures and imprecise transfer of the geometrical characterization of complex roughness structures into two-dimensional parameters. After the geometric characterization of roughness by the equivalent sand grain roughness, the anisotropy of the roughness also has a significant impact on the boundary layer. Based on these results new numerical and experimental methods has been developed to clarify the physical settings of loss appearance, as well as a work out of first approaches for model-based predictions of roughness effects.

Effect of different roughness configurations on the wake flow velocity distribution (u), the vorticity (ω), and the turbulent production (P) determined from PIV measurements in the cascade wind tunnel of the TFD

CURRENT RESEARCH AND OUTLOOK

The main scientific objective of the running third funding period is the establishment of a model to predict the impact of complex roughness on the performance and the efficiency of multistage power plants with Computational Fluid-Dynamics (CFD). This includes the validation of the developed and implemented model, as well as the data supply of sensitivities concerning power plant module performance and efficiency in the face of complex roughness. Subsequently, these sensitivities shall be used for the rating of different regeneration modes on the power plant. If the complex surface structure is known, the development of the model-based method with finalizing the project can be transferred to the flow of many technical surfaces, like e.g. wind energy plants and stationary gas turbines.

Experimental results of the flow over isotropic and anisotropic roughness structures with the same height, but with different directions and the resulting turbulent energy distribution

PUBLICATIONS

  • Gilge, P.; Hohenstein, S.; Seume, J. R. (2017) Experimental Investigation of the Aerodynamic Effect of Local Surface Roughness on a Turbine BladeInternational Journal of Gas Turbine, Propulsion and Power System
  • Gilge P.; Mulleners, K. (2016) Resulting Aerodynamic Losses of Combinations of Localized Roughness Patches on Turbine BladesAIAA Journal 54 (8), S. 2552–2555
    DOI: 10.2514/1.J054602
  • Mulleners, K.; Gilge, P.; Hohenstein, S. (2014) Impact of Surface Roughness on the Turbulent Wake Flow of a Turbine BladeJournal of Aerodynamics 2014, S. 1–9
    DOI: 10.1155/2014/458757
All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Non-public person

STAFF

M. Sc. Hendrik Seehausen
Address
Appelstraße 9
30167 Hannover
Building
Room
003
Address
Appelstraße 9
30167 Hannover
Building
Room
003