A low-Mach number fix for Roe’s approximate Riemann solver

et al. 2016

Journal of Aircraft

This paper presents an aerodynamic study of bodies related to lighter than air vehicles, using Computational Fluid Dynamics. The work begins with the validation of the CFD method using a 6:1 prolate spheroid. The validated method is then employed for the study of the flow around a shape similar to the Airlander aircraft of Hybrid Air Vehicles Ltd. An overview of the flow around is presented, supported by pressure survey, flow visualisation and transitional flow effects. The sensitivity of the transition location to the Reynolds number is also demonstrated, and the role of each component of the vehicle is analysed in terms of its effect on the flow-field, the lift and drag, and stability in pitch. It was found that the fins contributed the most to increase the lift and drag coefficients.

Section: Methodsmentioning

confidence: 99%

Analysis of Hybrid Air Vehicles Using Computational Fluid Dynamics

Carrion

Steijl

et al. 2016

Journal of Aircraft

“…Osher's [16] upwind scheme is used for the discretisation of the convective terms and MUSCL [17] variable extrapolation is used to provide a formally 3rd order accurate scheme. To account for low-speed flows, the Low-Mach Roe scheme (LM-Roe) developed by Rieper [18] is employed [19]. The linearised system is solved using the generalised conjugate gradient method with a block incomplete lower-upper (BILU) pre-conditioner [20].…”

Section: Methodsmentioning

confidence: 99%

Study of Hybrid Air Vehicle Stability Using Computational Fluid Dynamics

Carrion

Biava

et al. 2017

Journal of Aircraft

This paper uses Computational Fluid Dynamics to predict aerodynamic damping of airships or hybrid air vehicles. This class of aircraft is characterised by large lifting bodies combining buoyancy and circulatory lift. Damping is investigated via forced oscillations of the vehicle in pitch and yaw. The employed method is verified using data for lighter than air vehicles. The use of fins and stabilisers was found to be beneficial. The rear part of the body was dominated by separated flow that contained more frequencies than the forcing frequency imposed on the body. The final design is seen to be dynamically stable across a range of conditions for small pitch angles.Nomenclaturė

“…Alternatively, overset grids can be used with the details presented in Jarkowski et al (2013). To account for low-speed flows, the Low-Mach Roe scheme (LM-Roe) developed by Rieper (2011) is employed for wind turbine cases (Carrión et al (2013)). …”

Section: Methodsmentioning

confidence: 99%

Demonstration of a coupled floating offshore wind turbine analysis with high-fidelity methods

Leble

Journal of Fluids and Structures

2016

This paper presents results of numerical computations for floating off-shore wind turbines using, as an example, a machine of 10-MW rated power. The aerodynamic loads on the rotor are computed using the Helicopter Multi-Block flow solver developed at the University of Liverpool. The method solves the Navier-Stokes equations in integral form using the arbitrary LagrangianEulerian formulation for time-dependent domains with moving boundaries. Hydrodynamic loads on the support platform are computed using the Smooth-ed Particle Hydrodynamics method, which is mesh-free and represents the water and floating structures by a set of discrete elements, referred to as particles. The motion of the floating offshore wind turbine is computed using a Multi-Body Dynamic Model of rigid bodies and frictionless joints. Mooring cables are modelled as a set of springs and dampers. All solvers were validated separately before coupling, and the results are presented in this paper. The importance of coupling is assessed and the loosely coupled algorithm used is described in detail alongside the obtained results.