Peter Horst

Multidisciplinary Integrated Preliminary Design Applied to Unconventional Aircraft Configurations

A preliminary aircraft design tool is presented as a means of performing multidisciplinary, integrated preliminary design of unconventional aircraft configurations. Higher fidelity numerical methods for some of the involved disciplines are discussed as key elements of this process. A noise propagation module is described as a first step toward introducing aircraft noise analysis into the preliminary design process. Application of the tool to a specific unconventional aircraft concept is shown. The results of this study provide an understanding of why multidisciplinary design analysis and optimization, as well as higher fidelity methods, are required for the design of unconventional aircraft configurations.

Efficient Surrogate Modelling of Nonlinear Aerodynamics in Aerostructural Coupling Schemes

This paper considers the substitution of the computational-fluid-dynamics solver within an aerostructural coupling scheme by an efficient reduced-order surrogate model to realize high-fidelity nonlinear aeroelastic analyses within a fraction of the time compared to the corresponding coupled computational-fluid-dynamics analysis. The presented surrogate model approach is a combination of parameter reduction via proper orthogonal decomposition and system identification methods designed to cover nonlinear aerodynamic effects such as viscosity as well as transient effects. The investigated test case is the thick NLR7301 airfoil that shows significant nonlinear aerodynamic behavior along with nonnegligible viscous effects. The model is identified from a set of transient forced motion computational-fluid-dynamics analyses. After identification, the model is used to predict the discrete surface force distribution of the NLR7301 airfoil in static as well as transient coupled analyses. It is shown that the static ...

Computational Aero-Structural Coupling For Hypersonic Applications

For the coupled thermal and mechanical analysis of spacecraft structures, a simulation environment has been developed within the German IMENS project. The software environment combines existing and validated fluid and structural analysis codes and provides state-of-the-art techniques for a numerical coupling. The numerical concept is based on the weak formulation of the interface conditions on the coupling surface. The approach enables the coupling of non-matching surface grids in this environment. Sequential and iterative staggered schemes are available to handle transient and steady state problems. Aspects of the developed flexible software architecture and some of its implementation details are described. Applications to spacecraft structures demonstrate the environments features.

Multidisciplinary Integrated Preliminary Design Applied to Future Green Aircraft Configurations

The Preliminary Aircraft Design and Optimization tool (PrADO) is presented as a means of performing multidisciplinary, integrated preliminary design of unconventional aircraft configurations, with a focus on green aircraft concepts. High fidelity numerical methods for some of the involved disciplines are discussed as key elements of this process. A noise propagation module is described as a first step towards introducing aircraft noise analysis into the preliminary design process. Application of the tool to a specific Low Noise Aircraft (LNA) concept is shown. Although the structural weight of the LNA is significantly higher than that of a conventional reference aircraft designed for the same transport mission, the results of the design analysis indicate that the LNA can still achieve advantages in terms of direct operating costs if certain economic and operational conditions are met.

Improved Representation of High-Lift Devices for a Multidisciplinary Conceptual Aircraft Design Process

*† ‡ A methodology for improving the quality of high lift system performance prediction within a multidisciplinary preliminary design process is presented. The high lift system geometry is explicitly modeled and a multiple lifting line method is used to compute its aerodynamic characteristics. Computation times are suitable for use in a preliminary design process, and the results for several test cases show good agreement with wind tunnel and/or high fidelity numerical data. In addition, the method allows for further enhancement by using non-linear airfoil polars for interpolation, improving drag prediction and introducing some degree of non-linear aerodynamic behavior.

Experimental and Numerical Fluid-Structure Analysis of Rigid and Flexible Flapping Airfoils

A combined experimental and computational study is presented for an airfoil undergoing a combined pitching and plunging motion at Reynolds number 100,000, where transition takes place along laminar separation bubbles. The numerical simulation approach addresses unsteady Reynolds-averaged Navier―Stokes solutions and covers transition prediction for unsteady mean flows. To study the effect of wing flexibility, the aerodynamic computational method is coupled with a structural solver using a Galerkin method. The numerical simulations are validated using high-resolution, phase-locked stereoscopic particle image velocimetry for one flapping case with a reduced frequency of k = 0.2. Hereby both a rigid and a flexible birdlike airfoil are investigated. The flow reveals strong unsteadiness resulting in moving laminar separation bubbles, both well captured by the numerical simulations performed in this study.

Coupling techniques for computational non-linear transient aeroelasticity

Abstract Some numerical aspects for the coupling process of a discrete non-linear aeroelastic system are presented. The objective of this paper is two-fold: first, a consistent time-integration method of the whole coupled system is developed and the robustness is shown. Second, several data transfer methods — conservative interpolation, Galerkin-based transfer, dual-Lagrange-based transfer, and Sobolev-norm-based transfer — are employed and the importance of an accurate transfer scheme is demonstrated. Numerical results obtained from simulations of an oscillating one-dimensional plate in a transonic flow and a three-dimensional wing example serve as a typical benchmark problem to show the applicability of the presented concepts and the importance on the behaviour of an aeroelastic system.

Coupled Numerical Simulation and Experimental Validation of the Electroimpulse De-Icing Process

The electroimpulse de-icing system is an alternative process of de-icing wing slat structures made of carbon-fiber-reinforced plastics or aluminum. Because of the interactions between the induced magnetic field and the structural deformation, it is necessary to couple these parts. This paper presents a three-dimensional simulation as well as experiments of flat plates made of aluminum or carbon-fiber-reinforced plastics. The simulation is characterized by electrical and structural finite element calculations, which are coupled in each time step. The current propagation is based on real tests that are executed at a special test rig. A coil, which is connected to an impulse generator, is used to induce magnetic forces. Flat plates of aluminum or carbon-fiber-reinforced plastics (with an additional aluminum doubler) were tested and deformation results were used to validate numerical simulations.

Structural Design and Aeroelastic Analysis of an Oscillating Airfoil for Flapping Wing Propulsion

To investigate the aeroelastic eects, the design as well as the numerical analysis of a flexible and oscillating airfoil is described in this contribution. Due to the interaction of the fluid flow with the structural system, a multiphysical approach is employed here, were firstly the airfoil shape for low speed range based on a bird’s hand foil is designed and secondly the structural subsystem is developed including the interaction eects of the fluid flow. Further, in this paper the investigation of low-Reynolds-number flows past this flexible and flapping airfoil is presented. Transition takes place along a laminar separation bubble. To predict the point of transition, a linear stability solver fully coupled to an unsteady Reynolds-averaged Navier-Stokes flow analysis code is utilized. Results of the simulation of the airfoil’s flapping motion in air are presented for specific parameters and discussed in detail.

Aerodynamics and Structural Mechanics of Flapping Flight with Elastic and Stiff Wings

The flapping flight mechanism is expected to provide revolutionary operation capabilities for tomorrow’s Micro Air Vehicles (MAV). The unsteady aerodynamics of the flapping flight is vastly different from traditional fixed-wing flyers. Boundary layers with moving laminar-turbulent transition, three-dimensional wake vortices and fluid-structure interaction with anisotropic wing structure are only a few examples for the challenging problems. To get basic understanding of these effects, the authors develop a computational method that is validated with boundary-layer measurements on flexible and inflexible, flapping wings in a wind-tunnel. The computational method solves the unsteady Reynolds-averaged Navier-Stokes equations and is combined with both transition prediction and fluid structure interaction capability. Using generic airfoils shapes inspired by seagulls and hawks, different aerodynamic, structural and kinematic effects are systematically analyzed on their influence on thrust and propulsive efficiency of the flapping flight mechanism. In particular, we demonstrate that a slight forward-gliding motion during the flapping downstroke can increase significantly thrust and efficiency.Wing elasticity however seems to lower the propulsive efficiency in the investigated cruise flight flapping case. Beyond,we show that the wake structure of 3D flapping wings generates an efficiency loss of about 10% compared to equivalent two-dimensional flapping cases.