197 research outputs found
Numerical Simulations on the PSP Rotor Using HMB3
This work presents CFD analyses of the isolated Pressure Sensitive Paint (PSP) model rotor blade
in hover and forward flight using the structured multi-block CFD solver of Glasgow University. In
hover, two blade-tip Mach numbers (0.585 and 0.65) were simulated for a range of blade pitch angles
using fully-turbulent flow and the k-ω SST model. Results at blade-tip Mach number of 0.585 showed
a fair agreement with experimental Figure of Merit and surface pressure coefficients obtained in the
Rotor Test Cell (RTC) at NASA Langley Research Center. Comparisons are presented at blade-tip
Mach number of 0.65 in terms of integral blade loads, surface pressure coefficients and position of
the tip-vortex cores with published numerical data. Finally, the flow around the PSP rotor in forward
flight was also computed at medium thrust (CT =0.006) and results were compared with published
experimental data
Prediction of Helicopter Rotor Hover Performance using High Fidelity CFD Methods
No abstract available
Real Time Wake Computations using Lattice Boltzmann Method on Many Integrated Core Processors
This paper puts forward an efficient Lattice Boltzmann method for use as a wake simulator suitable for
real-time environments. The method is limited to low speed incompressible flow but is very efficient and
can be used to compute flows “on the fly”. In particular, many-core machines allow for the method to be
used with the need of very expensive parallel clusters. Results are shown here for flows around
cylinders and simple ship shapes
Real Time Wake Computations using Lattice Boltzmann Method on Many Integrated Core Processors
This paper puts forward an efficient Lattice Boltzmann method for use as a wake simulator suitable for
real-time environments. The method is limited to low speed incompressible flow but is very efficient and
can be used to compute flows “on the fly”. In particular, many-core machines allow for the method to be
used with the need of very expensive parallel clusters. Results are shown here for flows around
cylinders and simple ship shapes
Parallel Performance for a Real Time Lattice Boltzmann Code
The paper will present the details of a Lattice Boltzmann solver running in real time for unsteady
wake computations. In addition to algorithmic implementation, computational results, single
core and parallel optimization of the methods are also discussed
Creating a Database of Helicopter Main Rotor Acoustics for Validation of CFD Methods
The work presents recent experiments at the Kazan National Technical University (KNRTU-KAI), related to helicopter acoustics. The objective is to provide a database of near-field experimental data suitable for CFD validation. The obtained set of data corresponds to a Mach-scaled rotor of known planform. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows easy and direct comparisons with CFD predictions, without the need to use far-field aeroacoustic methods
Helicopter Fuselage Drag ─ Combined Computational Fluid Dynamics and Experimental Studies
In this paper, wind tunnel experiments are combined with Computational
Fluid Dynamics (CFD) aiming to analyze the aerodynamics of
realistic fuselage con¦gurations. A development model of the ANSAT
aircraft and an early model of the AKTAI light helicopter were employed.
Both models were tested at the subsonic wind tunnel of KNRTU-KAI
for a range of Reynolds numbers and pitch and yaw angles. The force
balance measurements were complemented by particle image velocimetry
(PIV) investigations for the cases where the experimental force measurements
showed substantial unsteadiness. The CFD results were found to
be in fair agreement with the test data and revealed some §ow separation
at the rear of the fuselages. Once con¦dence on the CFD method was
established, further modi¦cations were introduced to the ANSAT-like
fuselage model to demonstrate drag reduction via small shape changes
Helicopter Wake Encounters in the Context of RECAT-EU
This work presents a first attempt to apply the RECAT-EU (European Wake Turbulence Categorisation and Separation Minima) methodology of fixed-wing aircraft separation to helicopters. The approach is based on a classification of helicopters in categories using their rotor diameter and weight combined with wake comparisons between different classes of fixed-wing aircraft and helicopters. Where necessary the upset caused by a wake encounter to a simple helicopter model is used to establish safe separation distances. The work is based on a very limited amount of data for wake strengths but shows that the principles of the RECAT-EU methodology are directly applicable to helicopters at least for landing and take-off. This research calls for further measurements of helicopter wakes with modern methods so that the suggested separation distances can be further ascertained and ultimately refined allowing for better and safer integration of fixed and rotary-wing traffic at airports
CAA Modeling of Helicopter Main Rotor in Hover
In this work rotor aeroacoustics in hover is considered. Farfield observers are used and the nearfield flow parameters are obtained using the in house HMB and commercial Fluent CFD codes (identical hexa-grids are used for both solvers). Farfield noise at a remote observer position is calculated at post processing stage using FW–H solver implemented in Fluent and HMB. The main rotor of the UH-1H helicopter is considered as a test case for comparison to experimental data. The sound pressure level is estimated for different rotor blade collectives and observation angles
Tiltrotor CFD part II: aerodynamic optimisation of tiltrotor blades
This paper presents aerodynamic optimisation of tiltrotor blades with high-fidelity computational
fluid dynamics. The employed optimisation framework is based on a quasi-Newton
method, and the required high-fidelity flow gradients were computed using a discrete adjoint
solver. Single-point optimisations were first performed, to highlight the contrasting requirements
of the helicopter and aeroplane flight regimes. It is then shown how a trade-off blade
design can be obtained using a multi-point optimisation strategy. The parametrisation of the
blade shape allowed to modify the twist and chord distributions, and to introduce a swept tip.
The work shows how these main blade shape parameters influence the optimal performance
of the tiltrotor in helicopter and aeroplane modes, and how a compromise blade shape can
increase the overall tiltrotor performance. Moreover, in all the presented cases, the accuracy
of the adjoint gradients resulted in a small number of flow evaluations for finding the optimal
solution, thus indicating gradient-based optimisation as a viable tool for modern tiltrotor
design
- …