What Do Airplane Winglets Do?

Airplane WingletsAir travelers can’t help but notice the ever-increasing presence of ‘winglets’ of different sizes and shapes at the tips of airplane wings. And anyone interested in fluid dynamics will no doubt have pondered what these airplane winglets do, how they improve aerodynamics, and why they are becoming almost ubiquitous on aircraft of all commercial manufacturers.

The basic technical background to this innovation was very eloquently outlined in a recent article. entitled Here’s the simple reason planes have winglets, including interesting insights from Boeing chief aerodynamicist Robert Gregg on their applicability to different aircraft. It provides a very nice account of how winglets can impact the aircraft aerodynamics, to minimize induced drag without lengthening the wing.

Winglets allow the wings to be more efficient at creating lift, which means planes require less power from the engines. That results in greater fuel economy, lower CO2 emissions, and lower costs for airlines.

The same wing length with lower induced drag has a number of benefits, ultimately and most importantly greater efficiency and lower pollution than would be otherwise possible for planes of a given size. So the motivation for airplane manufacturers to incorporate winglets into aircraft designs is clear!

The post peaked my interest because inevitably computational fluid dynamics (CFD) plays a key role in the development of such technology, as it allows engineers to explore a myriad of designs to work towards an optimum for a given aircraft. It is a highly visible and to my mind a classic example of where and how CFD can provide significant benefit when developing new and innovative technology. In other words, a great example to point to when describing my job at ANSYS to non-engineering friends and family! Not only that, it is also an application which highlights the need for a powerful set of physics modelling capabilities, not just in one area physics but in multiple physics, to allow for successful adoption of simulation-driven development.

Aerodynamic benefits of airplane winglets

For example, in this case, the clear aerodynamic benefits of a winglet must be weighed against other effects of modifying the wing tip geometry. Perhaps an obvious effect is on the structural mechanics of the wing, where the additional weight and forces must be properly accounted for in the design, and the modified deflection of the wing under the altered aerodynamic loading must be correctly determined. This interaction between the fluid forces of the air and the structural response of the wing can be addressed by highly integrated aeroelastic simulations performed by coupling ANSYS Mechanical with ANSYS CFD. The prediction of these aeroelastic effects is a topic of a series of AIAA workshops, with ANSYS actively participating in efforts to improve the accuracy and efficiency with which this can be done. If you are interested to learn more about ANSYS involvement in the aeroelasticity prediction workshop you can read more in this article from a few years ago and follow up to date progress at the workshop website.

Applications related to this also spring to my mind, several of which are closely tied to areas of recent focus in ANSYS development. One example is whether the presence of the winglet affects the propensity of the wing to ‘flutter’. Flutter is a key element of developments for turbomachinery applications, where blade flutter assessment is a key application driving recent and on-going work (see number 4 of 10 Reasons to be Excited About ANSYS 17.0 for Turbomachinery Simulation).

Flow over a model wing used in AIAA workshops in which ANSYS is participating, looking into improving the accuracy and efficiency of the prediction of aero-elasticity.

Flow over a model wing used in AIAA workshops in which ANSYS is participating, looking into improving the accuracy and efficiency of the prediction of aero-elasticity.

Another example is determining if designs with winglets impact aircraft safety in conditions prone to ice build-up. Last year’s acquisition by ANSYS of the assets of Newmerical Technologies International (NTI), with its industry-leading FENSAP-ICE system for icing simulation, was an important addition to the breadth of ANSYS capabilities, to allow such questions to be investigated with the confidence.

Comprehensive aircraft simulation including a nacelle bleed-air anti-icing system, showing impingement zones on the fuselage, wing and engine; heat fluxes from anti-icing on the nacelle lip; ice accretion from leftover water on the intake liner; and the impact of an ice slab on the fan blade.

Comprehensive aircraft simulation including a nacelle bleed-air anti-icing system, showing impingement zones on the fuselage, wing and engine; heat fluxes from anti-icing on the nacelle lip; ice accretion from leftover water on the intake liner; and the impact of an ice slab on the fan blade.

It’s also further testament to our commitment to aerospace industry needs. Since the acquisition, development of FENSAP-ICE capabilities and their integration into ANSYS have been progressing rapidly and we will be presenting a paper on the combined aerodynamic/icing simulation at the AIAA Aviation conference in Washington, DC next week. Stay tuned for more in upcoming releases!

So, much like the clear motivation for aircraft manufacturers to use winglets, winglets are an excellent example of what motivates developments at ANSYS!

 

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John Stokes

About John Stokes

John Stokes is Director for Aerospace Technology in the Fluid Business Unit, heading ANSYS’s development efforts targeted at aerospace industry needs for the simulation of fluid dynamics and fluid-structure interaction. John has previously had various technical and management roles in support, consulting, sales, and product management, in over 19 years with the organization. John holds undergraduate degrees in Mathematics and Mechanical Engineering from Dalhousie University and McGill, respectively, as well as a Master’s degree in Environmental Fluid Mechanics from the University of Waterloo.