Alex Gothow

Bio: Alex Gothow is an academic researcher. The author has contributed to research in topics: Propulsion & Aerospace engineering. The author has an hindex of 1, co-authored 2 publications receiving 3 citations.

Numerical Investigation of High-Lift Propeller Positions for a Distributed Propulsion System

Abstract: The aerodynamic propeller–wing interactions of a distributed propulsion system in a high-lift scenario were investigated. A [Formula: see text] computational fluid dynamics parameter study with steady-state Reynolds-averaged Navier–Stokes simulations of a wing segment and an actuator disk was conducted to determine the sensitivities and correlations of design parameters at high angles of attack. The parameter study revealed a significant lift augmentation (about [Formula: see text] at [Formula: see text]) but a decrease in propulsive efficiency (about [Formula: see text] at [Formula: see text]). With increasing angle of attack, the lift augmentation effect decreased (down to about [Formula: see text] at [Formula: see text]), whereas the propulsive efficiency decreased further (to about [Formula: see text] at [Formula: see text]). The design parameter presenting the largest sensitivity toward system performance was the vertical propeller position. The distance between the propeller and the wing had a comparatively minor effect, as long as the vertical propeller position was adapted accordingly. Propulsive performance could be significantly improved by tilting the propeller downward toward the inflow (by about [Formula: see text] for [Formula: see text] as compared to a nontilted propeller). A spanwise clustering of propellers (tip-to-tip distance of [Formula: see text]) appears to be beneficial when considering a predetermined amount of distributed propellers.

Assessment of the Actuator Line Method for the Aeroacoustic Simulation of Distributed Electric Propulsion

Abstract: Within this study, the capability of the Actuator Line Method (ALM) to simulate the noise emission of a high-lift distributed electric propulsion configuration is investigated under the framework of the Clean Sky 2 project DISPROP. Therefore, the blades of three propellers in tractor configuration are approximated as lines with several nodes to which force terms are applied. The forces are calculated based on polars, i.e. lift and drag, at discrete radial positions. Using the flow field data of the CFD simulation, the acoustic extrapolation is carried out with the Ffowcs Williams - Hawkings (FW-H) approach, which is further beneficial to separate the various noise sources. The obtained aeroacoustic results of the ALM are then compared to fully resolved (FR) simulations, where it is firstly ensured that the aerodynamic characteristics agree well with the FR simulation. It is shown that the overall sound pressure level (OSPL) characteristic is well predicted by the ALM, whereas slight discrepancies occurred in the propeller-wing interaction noise. Therefore, the propeller-wing interaction noise is evaluated more in depth by examining the wing surface pressure fluctuations and further using the surface pressure values as input for the FW-H equation. Finally, the parameter space was extended by increasing the Angle of Attack for the configuration to high-lift and stall conditions. Here, the deviations in the acoustic behavior between the ALM and FR simulations increase up to 5 dB in several directions. Nevertheless, the characteristic of the directivity is also well predicted in these conditions and the ALM delivers overall high quality aeroacoustic data. Beside the capability of the ALM to perform propeller parameter studies without creating a body mesh, the advantage of the ALM is to save computational time. It was found that for this DEP configuration, a time saving of 10% could be achieved by using the ALM instead of the fully resolved propeller blades.