Evaluating ship superstructure aerodynamics for maritime helicopter operations through CFD and flight simulation

2016 ◽  
Vol 120 (1232) ◽  
pp. 1578-1603 ◽  
Author(s):  
J.S. Forrest ◽  
C.H. Kaaria ◽  
I. Owen
Keyword(s):  
Fluid Dynamics ◽  
Ship Design ◽  
Flight Simulation ◽  
Flight Mechanics ◽  
Naval Vessel ◽  
Simulation Tools ◽  
Rear Edge ◽  
Design Changes ◽  
Helicopter Landing ◽  
Operational Envelope

ABSTRACTThe unsteady air flow over and around the helicopter landing deck of a naval vessel is known to cause high pilot workload and to limit the helicopter's operational envelope for launch and recovery. Previous research has suggested that modifications to the ship's hangar edges can beneficially modify the flow over the deck. This paper examines the effectiveness of five hangar-edge modifications using computational fluid dynamics–generated airwakes and flight mechanics modelling, as well as piloted flight trials in a motion-base simulator. Results are presented, in terms of unsteady helicopter loads and pilot workload ratings, for modifications to the windward vertical rear edge of the hangar and with an oblique wind. The results demonstrate that while the airwake can be altered by superstructure modifications, the integrated effect of the altered airwake on the entire helicopter does not necessarily give the desired result; indeed of the five modifications tested, two were seen to be beneficial while three caused an increase in pilot workload compared with the unmodified hangar. Overall, the paper shows that the airwake can be modified by superstructure design changes, and that the effect on the helicopter can be measured through modelling and simulation. It is also demonstrated that making judgements on the severity of the airwake based on the aerodynamic flow field alone can be misleading. The benefit of these simulation tools is that they can be used during the ship design process to evaluate the effect of the superstructure aerodynamics, rather than wait until after the ship is built.

Computational fluid dynamics modelling of hydraulics and sedimentation in process reactors during aeration tank settling

2006 ◽  
Vol 53 (12) ◽  
pp. 257-264 ◽  
Author(s):  
M.D. Jensen ◽  
P. Ingildsen ◽  
M.R. Rasmussen ◽  
J. Laursen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Control Method ◽  
Waste Water Treatment ◽  
Aeration Tank ◽  
Cfd Modelling ◽  
Design Changes ◽  
Dynamics Modelling ◽  
Tank Design ◽  
Tank Settling

Aeration tank settling is a control method allowing settling in the process tank during high hydraulic load. The control method is patented. Aeration tank settling has been applied in several waste water treatment plants using the present design of the process tanks. Some process tank designs have shown to be more effective than others. To improve the design of less effective plants, computational fluid dynamics (CFD) modelling of hydraulics and sedimentation has been applied. This paper discusses the results at one particular plant experiencing problems with partly short-circuiting of the inlet and outlet causing a disruption of the sludge blanket at the outlet and thereby reducing the retention of sludge in the process tank. The model has allowed us to establish a clear picture of the problems arising at the plant during aeration tank settling. Secondly, several process tank design changes have been suggested and tested by means of computational fluid dynamics modelling. The most promising design changes have been found and reported.

Numerical Analysis of the LCS 2 airwake to understand potential interactions during helipcopter operations

2015 ◽  
Author(s):  
Brent S. Paul
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Analysis ◽  
Flow Field ◽  
Ship Design ◽  
It Impacts ◽  
Flight Envelope ◽  
Computational Fluid Dynamics Cfd ◽  
Potential Interactions ◽  
Flight Deck

The successful integration of aviation capabilities aboard ships is a complex endeavor that must balance ship design with the flight envelope of the helicopter. This can be particularly important when considering air wakes and other flow around the superstructure as it impacts the flight deck. This flow can generate unsteady structures that may interfere with safe helicopter operations. Computational fluid dynamics (CFD) is commonly used to characterize the flow field and assess potential impacts to the flight envelope, which can be used to help define an operating envelope for helicopter operations.

scholarly journals Integration of fast fluid dynamics and Markov chain model for predicting transient particle transport in buildings

2019 ◽  
Vol 111 ◽  
pp. 04030
Author(s):  
Wei Liu ◽  
Chun Chen
Keyword(s):  
Fluid Dynamics ◽  
Markov Chain ◽  
Particle Transport ◽  
Markov Chain Model ◽  
Lagrangian Model ◽  
Air Distribution ◽  
Chain Model ◽  
Indoor Environments ◽  
Eulerian Model ◽  
Simulation Tools

Fast simulation tools for the prediction of transient particle transport are critical in designing the air distribution indoors to reduce the exposure to indoor particles and associated health risks. This investigation proposed a combined fast fluid dynamics (FFD) and Markov chain model for fast predicting transient particle transport indoors. The solver for FFD-Markov-chain model was programmed in OpenFOAM, an open-source CFD toolbox. This study used a case from the literature to validate the developed model and found well agreement between the transient particle concentrations predicted by the FFD-Markov-chain model and the experimental data. This investigation further compared the FFD-Markovchain model with the CFD-Eulerian model and CFD-Lagrangian model in terms of accuracy and efficiency. The accuracy of the FFD-Markov-chain model was similar to that of the other two models. For the studied case, the FFD-Markov-chain model was 4.7 times faster than the CFD-Eulerian model, and it was 137.4 times faster than the CFD-Lagrangian model in predicting the steady-state airflow and transient particle transport. Therefore, the FFD-Markov-chain model is able to greatly reduce the computing cost for predicting transient particle transport in indoor environments.

scholarly journals Tunnel/Predictor Display for Trajectory Control in Hypersonic Flight

2018 ◽  
Vol 47 (2) ◽  
pp. 157-165
Author(s):  
Csaba Moravszki ◽  
József Rohács ◽  
Gottfried Sachs
Keyword(s):  
Flight Control ◽  
Research Effort ◽  
Trajectory Control ◽  
Flight Simulation ◽  
Flight Mechanics ◽  
Research Center ◽  
Control Law ◽  
3 Dimensional ◽  
Hypersonic Flight ◽  
Guidance Information

A tunnel/predictor display which presents guidance information in a 3-dimensional format is considered for improving trajectory control in hypersonic flight. The displayed 3-dimensional information comprises a tunnel image and a predictor for indicating the aircraft position at a specified time ahead. The 3-dimensional guidance information is introduced to support the pilot in controlling the flight path. It is considered that piloting problems can be avoided which exist with conventional trajectory control techniques due to path-attitude decoupling. A predictor control law is constructed which yields controlled element properties (predictor-aircraft system) requiring minimum pilot compensation. This predictor control law forms the basis of the trajectory control improvement goal. Results from hypersonic flight simulation tests at the NASA Dryden Flight Research Center are presented for experimental verification. This paper is an outcome of a joint research effort of the NASA Dryden Flight Research Center, and the Institute of Flight Mechanics and Flight Control of the Technische Universität München and the Department of Aeronautics, Naval Architecture and Railway Vehicles (former Department of Aircraft and Ships at the Budapest University of Technology and Economics.

STUDY OF AIRFLOW AROUND SHIP WITH RIGID SAIL ARRAY AND POTENTIAL ARRAY PROPULSIVE POWER

2021 ◽  
Vol 161 (A2) ◽  
Author(s):  
G M Atkinson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Ship Design ◽  
Fuel Oil ◽  
Cfd Analysis ◽  
Propulsive Force ◽  
Oil Consumption ◽  
Software Application ◽  
Computational Fluid Dynamics Cfd

An array of rigid sails installed on a large powered ship could provide a viable means to reduce fuel oil consumption (FOC) and emissions by using the power of the wind as a source of supplementary propulsion. This paper describes the study of airflow around a concept ship design fitted with 14 segment rigid sails (SRS) using a virtual wind tunnel software application and also investigates the propulsive force that a fixed sail array could provide using computational fluid dynamics (CFD) analysis.

Flight mechanics of a free-wing tilt-body aircraft

2008 ◽  
Vol 112 (1137) ◽  
pp. 625-640
Author(s):  
K. Ro ◽  
J. W. Kamman ◽  
J. B. Barlow
Keyword(s):  
Mathematical Model ◽  
Incidence Angle ◽  
Equations Of Motion ◽  
Dynamic Modelling ◽  
Flight Simulation ◽  
The Body ◽  
Flight Mechanics ◽  
Short Takeoff And Landing ◽  
And Control ◽  
The Mathematical Model

Abstract The free-wing tilt-body aircraft refers to a vehicle configuration in which the wing, fuselage, and empennage are in a longitudinally articulated connection. This allows the main wing to freely rotate relative to the body, while the empennage, which is in the form of a long twin boom connected to the rear of the body, changes its incidence angle relative to the body in response to external commands. The principal advantages claimed for the configuration are short takeoff and landing capability, and reduced gust sensitivity. The aerodynamics of the free-wing tilt-body configuration has been previously studied, but analysis of its flight mechanics is limited. In this paper we present derivations of the flight dynamic equations of motion using multi-body dynamic modelling techniques, and combine the resulting equations of motion with experimental aerodynamic data to achieve a nonlinear mathematical model for flight simulation of a generic free-wing tilt-body vehicle. The mathematical model is suitable for the study of detailed dynamic characteristics as well as for model based control law synthesis. Key flight performance, and stability and control characteristics of a generic configuration are obtained from the mathematical model.

Forced Combustion Experiments on Aero Combustors

2011 ◽  
Author(s):  
Nick Pilatis ◽  
Michael Whiteman ◽  
Paul Madden ◽  
Michael A. Macquisten ◽  
A. John Moran
Keyword(s):  
Transfer Function ◽  
Gas Turbine ◽  
Unsteady Aerodynamics ◽  
Significant Loss ◽  
Operating Conditions ◽  
System Level ◽  
End Point ◽  
Design Changes ◽  
Readiness Level ◽  
Operational Envelope

In the world of gas turbine combustion there is always the spectre of thermo-acoustic instability. Over the past few decades there has been significant effort afforded to researching the phenomenon of thermo-acoustics. The results of the research have produced numerous mathematical models and at system level these models have been used to predict and postdict where noise is likely to occur in a given system. The models also allow the combustion system to be numerically tested through the flight or operational envelope to identify areas where instability may occur before testing is carried out, thus reducing the risk of unexpected noise occurring. The weakness of many of these models is that they require, what is known as a flame transfer function. The flame transfer function is normally measured after the combustor has been fully designed and at a high TRL (Technology Readiness Level) so significant investment in time and money are already baked into the design. Remedial action if required can result in a significant loss of time and money in the development of the combustor. This paper describes the design and use of a test rig that allows combustion systems to be tested at much lower TRL. A ‘siren’ rig has been developed and used to identify what particular design changes in either combustor flow field or fuel delivery systems have effects on the thermo-acoustics. The exit boundary of the unit has a representative choked end point. This end point has the ability to be modulated in time, thus forcing the whole system. How the system reacts to the forcing is measured over a range of frequencies. The rig has been successfully used to influence design changes required to avoid combustion driven oscillations within the next generation of aero gas turbine combustors. The rig is not a representation of a complete 360 degree annular combustor system, but of a smaller sector. The objective is to isolate the Fuel Spray Nozzle (FSN) and corresponding combustor sector from acoustic resonances and derive functions expressing the relationship between unsteady heat release rate and unsteady aerodynamics for a range of operating conditions by controlling the modulation of air mass flow rate. Such functions can be used in conjunction with acoustic linear theory to predict wave modes and growth rates in combustor geometries.

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