Scramjet lift, thrust and pitching-moment characteristics measured in a shock tunnel

Lift, pitching moment, and thrust/drag on a supersonic combustion ramjet were measured in the T4 free-piston shock tunnel using a three-component stress-wave force balance. The scramjet model was 0.567 m long and weighed approximately 6 kg. Combustion occurred at a nozzle-supply enthalpy of 3.3 MJ/kg and nozzle-supply pressure of 32 MPa at Mach 6.6 for equivalence ratios up to 1.4. The force coefficients varied approximately linearly with equivalence ratio. The location of the center of pressure changed by 10% of the chord of the model over the range of equivalence ratios tested. Lift and pitching-moment coefficients remained constant when the nozzle-supply enthalpy was increased to 4.9 MJ/kg at an equivalence ratio of 0.8, but the thrust coefficient decreased rapidly. When the nozzle-supply pressure was reduced at a nozzle-supply enthalpy of 3.3 MJ/kg and an equivalence ratio of 0.8, the combustion-generated increment of lift and thrust was maintained at 26 MPa, but disappeared at 16 MPa. Measured lift and thrust forces agreed well with calculations made using a simplified force prediction model, but the measured pitching moment substantially exceeded predictions. Choking occurred at nozzle-supply enthalpies of less than 3.0 MJ/kg with an equivalence ratio of 0.8. The tests failed to yield a positive thrust because of the skin-friction drag that accounted for up to 50% of the fuel-off drag.

Heat Transfer in an Airfoil Shaped Strut

The heat transfer from a hot primary flow stream passing over the outside of an airfoil shaped strut to a cool secondary flow stream passing through the inside of that strut was studied experimentally and numerically. The results showed that the heat transfer on the inside of the strut could be reliably modeled as a developing flow and described using a power law model. The heat transfer on the outside of the strut was complicated by flow separation and stall on the suction side of the strut at high angles of attack. This separation was quite sensitive to the condition of the turbulence in the flow passing over the strut, with the size of the separated wake changing significantly as the mean magnitude and levels of anisotropy were varied. The point of first stall moved by as much as 15% of the chord, while average heat transfer levels changed by 2-5% as the inlet condition was varied. This dependence on inlet conditions meant that comparisons between experiment and steady RANS based CFD were quite poor. Differences between the CFD and experiment were attributed to anisotropic and unsteady effects. The coupling between the two flows was shown to be quite low - that is to say, heat transfer coefficients on both the inner and outer surfaces of the strut were relatively unaffected by the temperature of the strut, and it was possible to predict the temperature on the strut surface quite reliably using heat transfer data from decoupled tests, especially for CFD simulations.

Model reduction for nonlinear aerodynamics and aeroelasticity using a Discrete Empirical Interpolation Method

A novel surrogate model is proposed in lieu of Computational Fluid Dynamics (CFD) solvers, for fast nonlinear aerodynamic and aeroelastic modeling. A nonlinear function is identified on selected interpolation points by
a discrete empirical interpolation method (DEIM). The flow field is then reconstructed using a least square approximation of the flow modes extracted
by proper orthogonal decomposition (POD). The aeroelastic reduce order
model (ROM) is completed by introducing a nonlinear mapping function
between displacements and the DEIM points. The proposed model is investigated to predict the aerodynamic forces due to forced motions using
a N ACA 0012 airfoil undergoing a prescribed pitching oscillation. To investigate aeroelastic problems at transonic conditions, a pitch/plunge airfoil
and a cropped delta wing aeroelastic models are built using linear structural models. The presence of shock-waves triggers the appearance of limit
cycle oscillations (LCO), which the model is able to predict. For all cases
tested, the new ROM shows the ability to replicate the nonlinear aerodynamic forces, structural displacements and reconstruct the complete flow
field with sufficient accuracy at a fraction of the cost of full order CFD
model.

Aerodynamic behavior of an airfoil with morphing trailing edge for wind turbine applications

The length of wind turbine rotor blades has been increased during the last decades. Higher stresses arise especially at the blade root because of the longer lever arm. One way to reduce unsteady blade-root stresses caused by turbulence, gusts, or wind shear is to actively control the lift in the blade tip region. One promising method involves airfoils with morphing trailing edges to control the lift and consequently the loads acting on the blade. In the present study, the steady and unsteady behavior of an airfoil with a morphing trailing edge is investigated. Two-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations are performed for a typical thin wind turbine airfoil with a morphing trailing edge. Steady-state simulations are used to design optimal geometry, size, and deflection angles of the morphing trailing edge. The resulting steady aerodynamic coefficients are then analyzed at different angles of attack in order to determine the effectiveness of the morphing trailing edge. In order to investigate the unsteady aerodynamic behavior of the optimal morphing trailing edge, time-resolved RANS-simulations are performed using a deformable grid. In order to analyze the phase shift between the variable trailing edge deflection and the dynamic lift coefficient, the trailing edge is deflected at four different reduced frequencies for each different angle of attack. As expected, a phase shift between the deflection and the lift occurs. While deflecting the trailing edge at angles of attack near stall, additionally an overshoot above and beyond the steady lift coefficient is observed and evaluated.

Heat Transfer in an Airfoil Shaped Strut

Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2016-08-31 09:37:50.239

Metastability and emergent performance of dynamic interceptive actions

Objectives: Adaptive patterning of human movement is context specific and dependent on interacting constraints of the performer–environment relationship. Flexibility of skilled behaviour is predicated on the capacity of performers to move between different states of movement organisation to satisfy dynamic task constraints, previously demonstrated in studies of visual perception, bimanual coordination, and an interceptive combat task. Metastability is a movement system property that helps performers to remain in a state of relative coordination with their performance environments, poised between multiple co-existing states (stable and distinct movement patterns or responses). The aim of this study was to examine whether metastability could be exploited in externally paced interceptive actions in fast ball sports, such as cricket. Design: Here we report data on metastability in performance of multi-articular hitting actions by skilled junior cricket batters (n = 5). Methods: Participants’ batting actions (key movement timings and performance outcomes) were analysed in four distinct performance regions varied by ball pitching (bounce) location. Results: Results demonstrated that, at a pre-determined distance to the ball, participants were forced into a meta-stable region of performance where rich and varied patterns of functional movement behaviours emerged. Participants adapted the organisation of responses, resulting in higher levels of variability in movement timing in this performance region, without detrimental effects on the quality of interceptive performance outcomes. Conclusions: Findings provide evidence for the emergence of metastability in a dynamic interceptive action in cricket batting. Flexibility and diversity of movement responses were optimised using experiential knowledge and careful manipulation of key task constraints of the specific sport context.

Bluebird AR

"What is Bluebird AR? Bluebird AR was the ABC's alternate reality drama set around the leak of Bluebird, a clandestine geoengineering initiative created by eco-billionaire Harrison Wyld. Proposing a fictional scenario set against a backdrop of real world possibilities, Bluebird AR took some of the conventions of the well-established alternate reality game (ARG) genre and pulled them into the relatively new area of online drama, to create a hybrid entertainment form best described as 'participatory drama'. With Bluebird AR's interactive narrative centred on the experimental science of geoengineering, the deliberate manipulation of the Earth's atmosphere to counteract global warming, the events and characters in the Bluebird story were entirely fictional but fused with reality online. Inhabiting a mixture of third party social media spaces and websites created by the ABC, the story incorporated real online articles, scientific journals, media and debate around geoengineering. In an Australian first, ABC Innovation launched Bluebird AR on 27 April 2010, with a 6 week live phase. Audience members were invited to play collectively to help 'unlock the drama' and push forward the emerging narrative, or passively watch the story unfold in real-time across the internet. Bluebird AR subverted ARG conventions with the high quality of its production and assets, and raised the stakes for online drama with its level of audience participation." © 2014 ABC "Introduction One of the most exciting creative challenges of producing Bluebird AR was formulating the broad array of visual styles and treatments required for the project's diverse range of content. Many assets also needed to translate well not only online but across other media, including television and print. With the project's producers keen to create a visually rich narrative with high production values from the outset, inspiration for the production design for various aspects of the Bluebird story began in the earliest pitching phase in September 2008. Particular visual treatments and styles for Bluebird's characters, their web spaces and real world possessions were formulated concurrently with the creation of their profiles. Ideas around how various clues and gameplay spaces might look and feel were also explored at this early stage. Bluebird AR's small but tight creative team produced 7 website designs and brands, motion graphics for title sequences and logo animations, rotoscope animation, 3D compositing and animation, 3D wireframes and schematics, countless Photoshop composites, and a vast array of character assets for the DC (including Kyle's Bluebird Labs security pass and resignation letter, Kruger's American and Russia passports and birth certificate, Harrison's divorce papers, and more)…" © 2014 ABC

Operationalizing Supply Chain vs. Supply Chain Competion

Competition is an immensely important area of study in economic theory, business and strategy. It is known to be vital in meeting consumers’ growing expectations, stimulating increase in the size of the market, pushing innovation, reducing cost and consequently generating better value for end users, among other things. Having said that, it is important to recognize that supply chains, as we know it, has changed the way companies deal with each other both in confrontational or conciliatory terms. As such, with the rise of global markets and outsourcing destinations, increased technological development in transportation, communication and telecommunications has meant that geographical barriers of distance with regards to competition are a thing of the past in an increasingly flat world. Even though the dominant articulation of competition within management and business literature rests mostly within economic competition theory, this thesis draws attention to the implicit shift in the recognition of other forms of competition in today’s business environment, especially those involving supply chain structures. Thus, there is popular agreement within a broad business arena that competition between companies is set to take place along their supply chains. Hence, management’s attention has been focused on how supply chains could become more aggressive making each firm in its supply chain more efficient. However, there is much disagreement on the mechanism through which such competition pitching supply chain against supply chain will take place. The purpose of this thesis therefore, is to develop and conceptualize the notion of supply chain vs. supply chain competition, within the discipline of supply chain management. The thesis proposes that competition between supply chains may be carried forward via the use of competition theories that emphasize interaction and dimensionality, hence, encountering friction from a number of sources in their search for critical resources and services. The thesis demonstrates how supply chain vs. supply chain competition may be carried out theoretically, using generated data for illustration, and practically using logistics centers as a way to provide a link between theory and corresponding practice of this evolving competition mode. The thesis concludes that supply chain vs. supply chain competition, no matter the conceptualization taken, is complex, novel and can be very easily distorted and abused. It therefore calls for the joint development of regulatory measures by practitioners and policymakers alike, to guide this developing mode of competition.

Turbulent flow computations on a hybrid cartesian point distribution using meshless solver LSFD-U

This paper may be considered as a sequel to one of our earlier works pertaining to the development of an upwind algorithm for meshless solvers. While the earlier work dealt with the development of an inviscid solution procedure, the present work focuses on its extension to viscous flows. A robust viscous discretization strategy is chosen based on positivity of a discrete Laplacian. This work projects meshless solver as a viable cartesian grid methodology. The point distribution required for the meshless solver is obtained from a hybrid cartesian gridding strategy. Particularly considering the importance of an hybrid cartesian mesh for RANS computations, the difficulties encountered in a conventional least squares based discretization strategy are highlighted. In this context, importance of discretization strategies which exploit the local structure in the grid is presented, along with a suitable point sorting strategy. Of particular interest is the proposed discretization strategies (both inviscid and viscous) within the structured grid block; a rotated update for the inviscid part and a Green-Gauss procedure based positive update for the viscous part. Both these procedures conveniently avoid the ill-conditioning associated with a conventional least squares procedure in the critical region of structured grid block. The robustness and accuracy of such a strategy is demonstrated on a number of standard test cases including a case of a multi-element airfoil. The computational efficiency of the proposed meshless solver is also demonstrated. (C) 2010 Elsevier Ltd. All rights reserved.

Parallel computing concepts and methods for floquet analysis of helicopter trim and stability

Floquet analysis is widely used for small-order systems (say, order M < 100) to find trim results of control inputs and periodic responses, and stability results of damping levels and frequencies, Presently, however, it is practical neither for design applications nor for comprehensive analysis models that lead to large systems (M > 100); the run time on a sequential computer is simply prohibitive, Accordingly, a massively parallel Floquet analysis is developed with emphasis on large systems, and it is implemented on two SIMD or single-instruction, multiple-data computers with 4096 and 8192 processors, The focus of this development is a parallel shooting method with damped Newton iteration to generate trim results; the Floquet transition matrix (FTM) comes out as a byproduct, The eigenvalues and eigenvectors of the FTM are computed by a parallel QR method, and thereby stability results are generated, For illustration, flap and flap-lag stability of isolated rotors are treated by the parallel analysis and by a corresponding sequential analysis with the conventional shooting and QR methods; linear quasisteady airfoil aerodynamics and a finite-state three-dimensional wake model are used, Computational reliability is quantified by the condition numbers of the Jacobian matrices in Newton iteration, the condition numbers of the eigenvalues and the residual errors of the eigenpairs, and reliability figures are comparable in both the parallel and sequential analyses, Compared to the sequential analysis, the parallel analysis reduces the run time of large systems dramatically, and the reduction increases with increasing system order; this finding offers considerable promise for design and comprehensive-analysis applications.