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Subsystem Synthesis
Published in Scott Jackson, Systems Engineering for Commercial Aircraft, 2020
Other functions which have emerged through practice are Alleviate Wing Load and Provide Lift Augmentation. The propulsion system alleviates wing loads by off-setting the lift load with its weight. It provides lift augmentation through strakes which cause the turbulent boundary layer to stay attached and thus improves the maximum lift coefficient, CLmax, during take-off. Another secondary, but important, function is Provide Noise Attenuation. The power plant achieves this function by integrated noise treatment involving many components. Berry (1993) cites the inlet, fan, compressor, fan nozzle, burner, turbine, and primary nozzle as being the principal noise sources.
Smoke Flow Visualization in Large Wind Tunnels and Flight Testing Using the Flying-Strut Traverser
Published in Wen-Jei Yang, Handbook of Flow Visualization, 2018
The model is a simple wing and body, with the wing made from a flat plate chamfered along the bottom of the leading edges. The planform has a low-aspect-ratio unswept shape with large forebody strakes. The flow is dominated by a strongly rolled-up vortex structure generated by the strakes.
Parametric data-based turbulence modelling for vortex dominated flows
Published in International Journal of Computational Fluid Dynamics, 2019
Matteo Moioli, Christian Breitsamter, Kaare A. Sørensen
The numerical simulation of vortex dominated flows becomes even more challenging when multiple vortices are present. In case of a double delta wing configuration, two vortices separate over the wing and potentially differ in their topologies, thus introducing different sources of error in the vortex turbulence modelling. Moreover, the vortices can interact, providing complex flow fields, different forms of vortex breakdown, and complex dependence on the flow condition. The NASA double delta wing (Erickson and Gonzalez 2006) provides a range of reliable experimental data for the research on turbulence modelling. The wing planform is composed by a strake with sweep angle of 76 and an aft wing of 40 sweep (Figure 13). Two of three measured junction fillet variations are investigated: the baseline junction and the parabolic fillet. The high swept strake generates a stable vortex which energises the wing vortex and shifts the breakdown downstream. This improves the efficiency of the wing at high angles of attack. The additional complexity introduced by multiple vortices increases the challenge of the turbulence model conditioning approach. For this paper, the flow at a Mach number of 0.5 is considered. Experimental data are available in terms of Pressure Sensitive Paint (PSP) images, static pressure measurements and integral forces; the integral forces are used as objective function (14) for the optimiser. The decision to use integral forces in this test case is justified by the intent to verify if the turbulence model terms are able to improve the accuracy and maintain a physical consistence even in the case that only global values are used. Furthermore, this provides relevant information about the potential application of the method when a dataset of certain aircraft is completely or mostly available in terms of integral aerodynamic coefficients. This type of dataset is likely to be present in different steps of an industrial aircraft design. Therefore, the approach consists of first optimising using integral forces as reference and subsequently testing the solution accuracy by also comparing static pressure and PSP data.