Aerofoil Simulator

[Lacy Tortelli]

Beforewe can start simulating however, we need to design our aerofoil. This is relatively straightforward, as there is a wealth of aerofoil coordinate data libraries online, and we can import those coordinates into SOLIDWORKS by using the Curve Through XYZ function.

You can copy the NACA 4415 aerofoil coordinates from the University of Illinois at Urbana-Champagne aerofoil database website, or you can obtain it from the AirfoilTools website here. Note, the AirfoilTools site has a nice visualization tool that shows you how the shape of the aerofoil geometry changes as you modify the NACA parameters, which is great if you want to know exactly what those NACA numbers mean.

Open up Microsoft Excel and copy/paste them into the first cell. You will notice that both X and Y coordinates have been copied into a single column, so in order to make them usable we need to separate them into individual columns.

Now we have our X, Y and Z coordinates in three columns. We can click File>Save As and select Text (Tab Delimited) from the drop down menu. Select a location to save the file to, pick a name for your file and click Save.

This will open the Curve File pane. Click Browse, and then locate the text file containing the cleaned up coordinate data that you exported from Excel. It will load the coordinates into the pane, as seen below.

Next, we want to make a centreline from the trailing edge to just beneath the leading edge. This will represent the chord length of the aerofoil, and once we have constrained it we can alter the chord length at will.

Then, we can select both the chord line and the tangent line, and constrain them so that they are perpendicular to each other. Why? Because when we rotate the sketch or extend the chord length, we want it to retain shape, and the perpendicular constraint will ensure that the whole thing remains aerofoil-shaped.

Load up the Flow Simulation add-in by clicking Tools > Add-ins and checking the SOLIDWORKS Flow Simulation box. Once it is loaded, select the Flow Simulation tab and click the Wizard button to start the Flow Simulation Wizard.

On page three (Analysis Type), we can select Internal or External study. Internal studies are for simulating flows that are constrained by some kind of vessel, such as a pipe, and external studies are for simulating flows around the outside of a body such as a truck or an aerofoil. So, we click External, and then press Next to advance to the next page.

The next page (Default Fluid) allows us to select the fluid in our study. This is an aerodynamic study, so we select Air from the top list and click Add. Once the default fluid has been added, we can click Next.

The final page that we need to deal with in the wizard is the Initial and Ambient Conditions page. This is where we set the temperature and pressure of the environment and the velocity of the flow in the x-direction. We have set the temperature and pressure to SSL (standard sea level) values and the velocity in x-direction to 55m/s (about 200km/h).

You will notice that the wizard has created a box around the wing. This is our Computational Domain, where all the magic happens. Think of it as the inside of a wind tunnel. Everything inside it is part of the simulation, and everything outside it is irrelevant.

Click on Computational Domain on the left hand panel (as seen below) and you will notice six handles appear on the box. Drag these handles until the domain box fits just around the wing model. Be sure to leave enough room at the fore and aft of the wing so we can get some sweet visualization of the fluid flow as it passes around the wing.

Being an aerodynamic simulation, we want to set goals that are relevant to this domain. So, go into the left-hand project simulation panel again, right click on Goals, and select Surface Goals. This will bring up a list of parameters that we wish to measure and visualise, and we can select the minimum, maximum and average for each goal.

First, we want to select the faces of the wing that we want included in the study. In the Surface Goals panel, click the blue Selection area to activate it and click all of the faces of the wing model.

Now that our simulation is set up, we can run it. You can find the Run button in the top ribbon (as seen below). Click it and you will see the solver screen appear, informing you of how many iterations are left.

Now the calculations have finished, we can go into the study panel on the left and expand the Results section to show us a selection of graphs and plots. Right clicking any of these plots will allow you to insert the plot into the main window.

In this instance, I select Front Plane, then I select Contours to show a contourplot. In the Contours section, you can see that the default parameter should be Velocity (X). We would like to see the pressure contours here, so we can click the parameters box and select Pressure.

Click the green check mark and you will see your plot appear in the main design window. You can move the slice along the length of the wing by using the green drag handle and you can rotate the plot as you would do your 3D model. The image below shows an isometric view and a side view. The color code shows how the colors relate to differences in pressure.

So, if I want to change from a pressure contour plot to a velocity contour plot, I simply click Pressure beneath the colored scale (as seen above) and switch it to velocity. The main plot will change accordingly.Note, if you want to see the slice scan along the entire length of the wing, you can right click on Cut Plot and select Play for a little animation.

In the Appearance section, we select Static option, and then we select the appearance of the trajectory. In this instance we select Pipes, but feel free to play around here and experiment with different appearances.

Phillip Keane is currently studying his PhD at the School of Mechanical and Aerospace Engineering at Nanyang Technological University, Singapore. His background is in aerospace engineering, and his current studies are focused on the use of 3D-printed components in spaceflight. He previously worked at Rolls-Royce and Airbus Military and served as an intern for Made In Space and the European Southern Observatory.

This article explained the human error and problems we've had in the past through out the constuction of certain aircraft causing control reversal. It only briefly touched on supersonic speeds and didn't "get to the point" which is the frustrating thing for me. i have since found a few websites which i'll post later which kind of explains it in a little more depth.

just talked to an FA/18 pilot on the weekend and proved that there infact no control reversal at transonic and supersonic altitudes. There is a slit stream effect which defys beouli's law where by the 2 air particles do not meet up on the triling edge on the aerofoil. This causes a low pressure around the trailing edge of the aerofoil making the controls become completely useless. To counter-act this problem they actulally make the "whole tip" (leading edge to the trailing edge) of the wings a combination of ailerons and elevators and they use the same concept for the rudder.

What was experienced by most soud barrior breaking pilots in the early days was something called the mach tuck where by the lift over the aerofoil caused by the sheer speed of the air over it, was so great that they had to fly with their nose down to keep it's altitude. This usually resulted the the plane being obliterated because force is not ment to be exerted on the top face of the aircraft.

the problem occurs when the amount of airflow over the wing becomes great enough that the force generated by the ailerons is enough to twist the wing itself, due to insufficient torsional stiffness of the wing structure. For instance when the aileron is deflected upwards in order to make that wing move down, the wing twists in the opposite direction. The net result is that the airflow is directed down instead of up and the wing moves upward, opposite of what was expected.

And since an F/A 18 most likely is not constructed to suffer from this effect, I wonder how a pilot could dismiss a theory (let's cal it a theory for the moment) like this so easily. What arguments did he give you?

You can get elevator reversal. It is cause when the load/forces on the elevator are large enough to cause a twisting moment on the deflected elevator surface. It causes a reverse in the aircrafts pitch attitude.

Well, know im not interested to know, I've seen this before and I have an extreme passion for aviation and have my PPL's. Im just merely saying this is a worthless and outdated topic not worth replying to.

I can see why you might be concerned about the idea of control reversal after breaking the sound barrier. However, let me assure you that while there is a phenomenon called "control reversal," it's not quite as dramatic as it might sound. Let me explain this in more detail.

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