# Questions tagged [aerodynamics]

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### Building a Peltier module mini-cooler

I am just a noobie in engineering stuff. Should the DC Fan 1 suck the air out of the Al heat sink OR push air into it for more efficient heat dissipation? For the small heat sink placed on the colder ...
18 views

### How to determine wedge angles, stagger angles, pitch, and chord for axial turbine mean-line modelling?

I would like to measure the performance and optimize the design of an axial turbine using mean-line modelling. However, most of the optimization codes I found on GitHub require wedge angles, stagger ...
35 views

### How should a stationary suspended spherical tube be modified to incorporate aerodynamic downforce mitigating both fore and aft 45 mph - 120 mph winds?

The question involves this topic; High-wind rollover damage in center-pivot irrigation systems. This study involves the additive engineering possibilities to achieving an aerodynamic remedy ...
30 views

### How does one calculate the aerodynamic pressure on a spacecraft during Max Q?

Just as lift - off of a spacecraft commences, that spacecraft undergoes aerodynamic pressure. After a certain point, the spacecraft reaches Max Q or maximum aerodynamic pressure. I do know that Max Q ...
23 views

### Characteristic scales in Thin Shear Layers Equations (Aerodynamics)

I am struggling to understand what characteristic scales mean in the context of thin shear layer equations. I am referring mostly to the following paragraph from the book "Turbulent Shear Layers ...
33 views

### How could I calculate the torque due to lift and drag in the body frame?

I'm trying to figure out the torque due to aerodynamic forces on an aircraft confined to two dimensions (so no sideslip). Defining the windframe with basis vectors $\hat{w_1}, \hat{w_2}$ obtained by ...
1 vote
48 views

### Why do wing-tip vortices cause an induced angle of attack upstream?

My question is the following. Wing-tip vortices induce a downward flow on the root side of the wing. So, if this induction happens at the wing, and these vortices are then shed downstream, why is ...
48 views

### Why do trailing edge flaps increase the CL,max of a wing?

I was wondering why do trailing edge flaps increase the lift co-efficient for a given angle of attack. I am guessing it has something to do with delayed flow separation, but this is quite unintuitive, ...
44 views

### How does a filter mesh/scotch-brite increase the thickness of the foam in foam spray?

On YouTube there are a lot of videos that show how to make a foam spray from a simple garden spray. One example you may see here: https://www.youtube.com/watch?v=kKUX5H7-xu0 (5:55 point is the most ...
234 views

### How does stalled diffuser/wing reduce drag at F1 car?

How stalled diffuser/wing reduce drag at F1 car if in aerodynamics stall/separation is always related to increase in drag? Any graph of pressure distribution when diffuser is stalled? From "...
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34 views

### Aerodynamic design and characteristic of fan vs blower

I just learnt about the difference between a fan and a blower, namely the former providing high flow rate at very low outlet pressure (<1.1*inlet) and the latter providing a slightly increased ...
5k views

### Can we add treadmill-like structures over the airplane surfaces to reduce friction, decrease drag and producing energy?

I am curious about a method to enhance the efficiency of passenger aircraft during cruise speeds by integrating treadmill-like structures on the fuselage and beneath the wings without changing the ...
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90 views

### Wind turbines on high-rise buildings?

Recently, it occured to me that there is a lot of "unused" space on flat-top buildings, and so I wondered, whether it wouldn't be a reasonable ideas to put (vertical) wind turbines on ...
54 views

### Why does CFD over predict shockwave in comparison to wind tunnel?

I ran a CFD simulation of Mach=0.85 flow over an aerofoil and noted that my Cp (coefficient of pressure) plot over predicts the shockwave in comparison to experimental data? Can someone please explain ...
69 views

### How does a fighter craft rebalance itself after it fires its munitions and missiles?

How does a fighter craft rebalance itself after it fires its missiles? Each missile could range anywhere from 40kgs up to 750kgs depending on the model. I am curious to know how a fighter craft ...
108 views

### Unable to validate hypersonic flatplate case in DSMC SPARTA

I'm trying to learn a software called DSMC SPARTA. I'm validating the hypersonic flatplate case mentioned in one of the tutorials on the website (Page 17). This was my test case: ...
1 vote
35 views

### Is there a way to 'switch OR engage/disengage' power between two different rotating shafts depending on a set RPM (wind speed)?

I'm a final year mechanical eng student, I'm working on designing a prototype of a 'Hybrid vertical axis wind turbine (VAWT)". This hybrid turbine consists of two types of VAWTs Savonius & ...
1 vote
46 views

### How will the motion of air be just before the isolation damper?

Let's say I have duct work shown as below. I have air moving from left to right with high velocity.There are two elbows and there is a damper of the same kind just before each of them and there is ...
909 views

### Why did the Mythbuster's dimple car get better fuel economy?

I'm trying to understand why the Mythbuster's dimple car gets better fuel economy - if it actually would as I'm not I understand that a golf ball functions by creating turbulent air flow and via the ...
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367 views

### Can a fluid have more or less static pressure than atmospheric pressure in atmosphere?

We assume static pressure of a fluid coming out of a pipe or nozzle of gas turbine with high temperature and velocity is equal to atmospheric pressure, which confuses me for some point. Does it mean ...
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67 views

### Why are there two fans in open circuit wind tunnel in laboratory?

In an experiment in hydraulics lab of my college, very recently someone asked me, why were there two fans in the open circuit wind tunnel. That wind tunnel is used for conducting experiment for ...
691 views

### Multiple inline fans

I have a chimney with a single 100 cfm exhaust fan. If I would add a second similar fan in the same chimney,in line with the first fan, what would happen? Would I move 200 cfm? Would I still move 100 ...
• 1
303 views

### How to theoretically determine the flow rate for a fan design?

I am trying to design a ducted axial fan. The fan will be pulling air through a filter, and ejecting out into the atmosphere (For a CO2 direct air capture application). However I want to start with ...
91 views

### Density or Pressure based solver CFD

I’m currently trying to simulate the 2d cross section of a bullet using Ansys Fluent but am really confused about which solver type to use- density or pressure based? Conditions: Transonic (M=0.8) ...
78 views

### What are the limits on plane speed?

I was thinking about an extremely narrow object and considering that I think in the ideal case it could only deal with the force of collision with air particles at the front of the projectile (...
38 views

### Pitot and static port placement - How to choose the ideal location

Forgive the this topic placement as it might be similar to other older ones (Although I a bit sure that the main contents might be different than other older ones). In the upcoming days I will have a ...
20 views

### How Does The Aerodynamics Of This Hanging Rotating Wing VAWT Turbine Function?

We are examining videos of this very fast rotating "hanging VAWT" shown on Youtube: https://youtu.be/O2MZsK0mvBk https://youtu.be/7hVQ_rVNRUI It say in the text description that "...
35 views

### how to calculate drag force (to be used later in the calculation of drag coefficient)

I'm working on a school project for car design (M segment car) we already found an open source Toyota model and can get the final answer online, but I want to know how can I calculate them what's on ...
1 vote
298 views

### What is the approximate horsepower/kW output of a cyclist riding a bike at near ~300km/h?

In 2018, a female cyclist set the outdoors record for fastest cycling clocking in at almost 300km/h. (https://en.m.wikipedia.org/wiki/Denise_Mueller-Korenek), and I am curious to know the approximate ...
400 views

### How to calculate missile's radius of turn?

I want to make a simple simulator game and in this game there is a missile that must hit something. The problem is, I can't find the equation to calculate its radius of turn. The game is a simulator ...
75 views

### Scroll design for off the shelf tangential/cross flow fan rotor

I'm trying to figure out a somewhat optimized fan scroll shape for a cross flow fan rotor I aquired. However I seem to have vastly underestimated the complexity as I have a lot of trouble finding ...
71 views

### How to calculate the increase in air speed from a wind nozzle / concentrator?

Given an inlet wind speed of $v_1$ and nozzle inlet area of $A_1$ and an outlet area $A_2$ what would be the outlet velocity. The nozzle/concentrator is positioned in an open field where the wind is ...
164 views

### Wind drag by a solar panel on an RV trailer

I installed my solar panel a couple weeks ago and now I'm not sure if I did it right. The first pic is mine the second is the other guy. it’s what brought up the curiosity, as this guy has the same ...
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208 views

### How air dam reduce drag and lift?

Few questions about air dam(flexibile vertical plate on front bumper) What is main purpose of air dam in car industry, reduce drag or reduce lift(increase downforce)? How dam reduce drag if : a)...
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36 views

### Converting differential pressure

I need to submit a lab report. I've measured: Differential pressure [Volts] Flow rate [Hz] Flow Rate [m^3/s] In my report I need to get the Pressure Differential in Pascal but how can I convert ...
67 views

### Does the weight of a pilot exponentially affect the necessary weight of human-powered aircraft?

The MIT Daedalus, a human-powered craft, weighed about 31 kg. This was significantly lighter than its pilot during its record setting trip, though I can't confirm the pilot's exact weight. Still, this ...
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125 views

### Releasing compressed air with the loudest pop

Due to the dry summer I've been thinking about theory of making cracker/banger without fire. Would connecting a nozzle (de Laval?) to quick release valve from small cylinder with the pressurised air ...
562 views

### How do water tunnel experiments compare to wind tunnel experiments?

I recently stumbled across the water tunnel videos by this guy: https://youtu.be/quDLzxmJl5I?t=838 He states that for his "high flow" experiments the water speed is at 0.668 m/s. The car ...
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49 views

### Governors and acceleration effect on IC engine

If a car is moving with a constant velocity this means that resistive loads (like air drag friction) should equal the driving force from the car; but I know that the governors always cancel the effect ...
129 views

### Angle of attack on variable pitch propeller?

For a variable pitch propeller where the angle of attack can be adjusted during flight, are the individual blades similar in design to standard propellers, with a low angle of attack at the edge of ...
450 views

### Why do air-to-air missiles have tail fins?

That sounds like a stupid question but hear me out. For something like a rocket where the goal is to fly in a straight line the use of the tail fins is obvious. But air-to-air missiles are designed to ...
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118 views

### What aerodynamic equation should be used to determine the drop in air pressure over an airfoil embedded within a vertical pipe?

I have a conceptual idea for a thruster for a VTOL aircraft/drone which should produce lift by utilizing a upward-flowing airflow to produce low air pressure over the top surface of an airfoil that is ...
78 views

### is there a difference in performance between these two fan designs

These two fans are usually used in hairdryer is there a difference between them in performance if both have same rpm and same outer diameter.
1 vote
291 views

### Where is best place to install vortex generators if race car diffuser stall?

If flow separate in high AoA diffuser, vortex generators can help to delay separation. Where is best palce to install VG for flat floor + diffuser configuration , in front leading edge of diffuser or ...
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1 vote
393 views

### What are the advantages of an asymmetrical missile nose cone?

Some rocket- and missile designs sport an asymmetrically conical nose cone. A prime example being the Stunner missile in "David's Sling" surface-to-air system. Several sources (such as ...
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308 views

### What are the practical applications of Centre of Mass & Centre of Gravity?

I have learnt COM and COG are different things if we have non uniform gravitational field i.e. mass will be same at anywhere but gravity will be different. I want to find practical examples of both ...
373 views

### Why wind turbine dont use high lift coefficient airfoils?

All wind turibne use low lift coefficent airfoils from 1.0 to 1.5. Why not use high CL airfoils to get maximum torque? http://airfoiltools.com/airfoil/details?airfoil=s812-nr
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67 views

### Why wind turbine with more blades rotate slower compare to one or two blades?

Why wind turbine with more blades rotate slower(lower RPM) than turbine with just one or two blades, if both has equal diameter on same wind speed? Often people say more blades have more drag, but ...
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