Calculation of lift and thrust

[pratikk]

I need some information and guidance on how to calculate net lift and thrust produced by wings of an MAV(micro air vehicle) which are flapping and active pitching.

I know only about one method which is the Blade Element Analysis, but it is just an approximation and doesn't accounts for pitching. Other methods are experimental testing but I don't want to go for it. I want to create a formulation of the design first and then make a prototype and for that I need to know about the lift and thrust generated by wings of 15cm span and inverse zimmerman planform.

 

[DylanB]

I'd check out a text by Azuma, "The Biokinetics of Flying and Swimming". It includes an inviscid model for a flat plate undergoing pitching and heaving motion, typical in flapping flight. You can extend the model however you like for your application, as the mathematics are not too complex.

I would not expect to get great results from an inviscid model however, as it will fail to predict the leading edge vortex dynamics, spanwise flows and stalling behaviour present in flows over aerofoils at low Reynold's numbers, which are critical to wing performance.

This area is being researched heavily lately, so I would do a literature search of recent papers on pitching and heaving aerofoils. If I recall you should be able to find some good data (both computationally and experimentally) given that your wing is actively pitching. I'm working presently on predicting the deformation characteristics of a passively pitching flapping wing.

 

[Travis_King]

which are critical to wing performance

Extremely. Especially in something like a flapping wing, in which the vortices are a major component of both lift and thrust.

 

[RandomGuy88]

Unsteady airfoil theory is not terribly difficult to use and it can be applied to a body in arbitrary motion. It is probably what DylanB is mentioning in the book. You may be able to extend this to create an unsteady lifting line code.

 

[alphy]

Thank you for your question. I can provide you with some information and guidance on calculating the net lift and thrust produced by wings of a micro air vehicle (MAV) that are flapping and actively pitching.

Firstly, you are correct in mentioning that the Blade Element Analysis (BEA) method is an approximation and does not account for pitching. This method is commonly used in the initial design phase of MAVs, as it provides a quick estimation of the lift and thrust forces. However, for a more accurate calculation, it is important to consider other factors such as wing geometry, airfoil shape, and pitching motion.

One approach to calculating lift and thrust for a flapping and pitching wing is through computational fluid dynamics (CFD) simulations. This method involves solving the Navier-Stokes equations to simulate the flow around the wing and calculate the resulting forces. CFD simulations can account for wing geometry and pitching motion, providing a more accurate estimation of lift and thrust compared to BEA.

Another approach is through analytical methods, such as the unsteady vortex-lattice method. This method combines the principles of vortex theory and potential flow theory to calculate the lift and thrust forces exerted by a flapping and pitching wing. It also takes into account the wing geometry and pitching motion, making it a more accurate method compared to BEA.

In terms of your specific MAV design with a 15cm wing span and inverse zimmerman planform, I would recommend using a combination of CFD simulations and analytical methods to calculate the lift and thrust. This will provide a more accurate estimation and can serve as a basis for your design formulation. However, it is important to keep in mind that these methods also have limitations and may require some experimental validation.

I hope this information and guidance helps you in your design process. I encourage you to continue exploring and experimenting with different methods to improve the accuracy of your calculations. Best of luck with your MAV design!