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Environmental challenges and the aerospace industry
Published in Wesley Spreen, The Aerospace Business, 2019
A current controversial topic attracting the interest of climate scientists is the possible effect of contrails upon climate. Contrails, which are condensation trails produced by jet aircraft, normally form only above altitudes of about 8 km, where temperatures are typically below −40°C. In that temperature range, ice crystals form spontaneously because water vapor from combustion sublimates directly into ice. Contrails can also be triggered by changes in air pressure at wingtip vortices or as air passes over the wing surface.
Pumps
Published in V. Dakshina Murty, Turbomachinery, 2018
The analysis used so far did not account for the possible losses. Thus, there is a deviation in the actual shape of the pump curve from that predicted by Equation 5.6. There are several reasons for this. The first is friction loss, which varies as Q2. The second loss is due to circulatory flow, resulting from leakage of the flow from the pressure side to the suction side of the blade, a process that occurs near the tip of the blade. This is similar to wingtip vortices that are formed on aircraft wings due to the leakage of flow from the high pressure below the wing to the low pressure above the wing. The relative velocity thus leaves with a value w2'>w2 at an angle β2'<β2. The result of this is that wu2'>wu2, which makes the value of Vu2'<Vu2, thereby reducing the head. This can be seen in Figure 5.5. The ratio of Vu2' to Vu2 is called the slip coefficient, μs. It depends on the amount of circulation, which in turn depends on the number of blades and the geometry of the flow passage. An approximate relationship for the slip coefficient has been given by Shepherd (1956) as follows:
Preliminary investigation on the effects of folding wingtips on the aerodynamics characteristics of flexible aircraft
Published in International Journal of Ambient Energy, 2022
V. Madhan Raj, Dilip A. Shah, P. Boomadevi
Wing is an essential part of aeroplane design. It enables to produce lift for an aeroplane. On commercial aircraft, the main objective is to reduce the drag which is created by the wingtip vortex and increasing the lift. This can be done by using winglets on the tip of the wings. The winglet is a part of a wing which is mainly used to reduce wingtip vortex, induced drag and fuel consumption. The prime objective of this project is by changing the angle of attack the efficiency of the winglet is improved. Reduced the wingtip vortices and induced drag maintains fuel saving up to 6% better lift performance (Whitcomb 1976). To study and analyse the effects of foldable wingtips at a various angle of attack the optimised method from literature is used. Winglet optimisation has great attention, because of its potential to reduce the induced drag. It is a vertical projection on the tip of the wing which reduces wingtip vortices and Induced Drag. Wingtip vortices are formed by the difference in pressure of above and below the wing. It also helps to improve aircraft characteristics and increases the aspect ratio. Accounting 40% of drag during the cruise and 80% of drag during in climb condition is occurring (Guerrero, Maestro, and Bottaro 2012). By reducing drag and fuel consumption thereby increasing lift performance made us to take up this idea. The aim of this project is to carry out the experimental analysis of foldable wingtips. When the aircraft moves in air, wingtip vortices are produced due to its lift generation. To reduce the vortex and by reducing the drag induced on the wing, the lift performance can be enhanced. The fabricated model will be tested in the wind tunnel for lift and drag characteristics (L/D ratio) and force measurement using load cell (Sohaib 2011). The experimental model is made in such a way that the winglet can be foldable up to a certain cant angle. By changing the Cant angle and Angle of attack of the wing and winglet during testing, the experimental data’s can be calculated for lift and drag coefficient using force measurement load cell (Manigandan, Kumar, et al. 2017). Figure 1 represents the winglet with different cant angles. The cant angles are as follows: 90, 180, 150, and 270 degrees.