Questions tagged [aerodynamics]

A subset of the [fluid-dynamics] tag concerning primarily forces such as lift and drag generated on bodies as they move through gasses or as gasses move through the body (typically air).

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6 views

What is the method to calculate wave drag of a biconvex aerofoil?

I wish for it to not use calculus, since I do not know much of it, and it is a computer program, but I'm OK with that. Thanks!
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Mach number at very high altitudes

The Mach number is defined as $$M = \frac{v_\infty}{a}$$ $v_\infty$ is the flow speed wrt the aircraft, and $a$ is the local speed of sound. For lower altitudes (within the troposphere) Mach number ...
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Is a moving wind turbine more efficient?

To begin with, let’s get the elephant out of the room; No, I’m not asking about free energy. Now onto the question: Wind turbines have a peak efficiency at some wind speed. Say the wind speed is ...
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Can an system (wind sail) move faster than the speed of the wind in the ground reference frame? [duplicate]

I just mean to be simple here, there are numerous articles on this platform itself regarding the exact topic and other information outside but I wanted to cover up the insight that I got here. After ...
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What it means that propellers produce lift?

I understand that the wings of a wind turbine are turning because the wind flows around them. Then due to their geometry a field of lower pressure is produced. And they are turning. But a propeller is ...
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Do stationary objects intoduce drag on closely passing moving objects

Would it require more energy to drive down a narrow road lined with columns than a similar open road? Would the columns intoduce drag on the passing vehicle, or effect its aerodynamics in any way?
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Are the lift and drag force on a wind turbine blade responsible for torque development?

Is the lift and drag force on a wind turbine blade are responsible for torque development? I understand that the torque and thrust are the decomposition of the net aerodynamic force on the turbine ...
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Calculating reentry of extremely low-denisty object

Assume I'm at an orbit similar to that of the ISS, going around 7.66 km/s around the Earth. There, using a foam sprayer or some similar contraption, I create a large, spherical, free-floating blob of ...
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John D. Anderson Fundamentals of Aerodynamics Example 2.2

I'm having trouble understanding the derivation of the integral for Coefficient of Friction in Example 2.2 of John Anderson's Fundamentals of Aerodynamics 5e. I'm not sure how the author cancels $$ ...
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How do you understand stall in terms of Newtonian mechanics (i.e. without Bernoulli's Principle)?

Okay, so. I understand how a wing generates life using Newtownian mechanics, to wit: the air molecules crash into wing, which is at an angle to the air molecules. As a result, the air molecules are ...
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How would the air flow rate be affected in a fan if it was subjected to moving air?

Now I know the flowrate in a given fan when it is kept stationary, but if the air around the fan is moving at some speed or if the fan itself is moving relative to the air, how would the effective ...
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Correlation between momentum and displacement thickness

I'm new to the problem of boundary layers, and came across the following task: Let us consider a stationary incompressible laminar flow around a flat plate at zero angle of attack. The coordinate x = ...
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Finding aerodynamic coefficients of an airfoil using numerical data measured in wind tunnel

I am trying to find all the aerodynamic coefficients of an airfoil at different angles of attack. I have .DAT files for data which have 4 columns of data all in order {angle of attack[deg], Lift[N], ...
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How do turbine engines improve compression ratio?

As I have learnt from the Venturi tube that Pressure is inversely proportional to velocity. When a general aircraft is flying at say Mach 0.8 and at the same time there is a pressure decrease with ...
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How can a butterfly dodge the windshield of a fast moving car?

While driving, an unlucky butterfly was about to hit my windshield. But instead of splattering, it sort of glided smoothly upwards across the surface of my windshield. The butterfly was clearly not ...
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Drag coefficient of a hemisphere

I am looking for the aerodynamic drag coefficient of a hemisphere that is set up to flow as follows: In the literature, I only found coefficients for the hemisphere placed in a different setting. ...
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Why does Wind Velocity over a wing to increases and what is its cause?

Why does wind velocity increase over a wing? Also I have a bit of a paradox, people explain lift by saying there is a lower pressure region on the top of the airfoil and a higher pressure region on ...
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Is there such thing as a non-turbulent wake?

We learnt in our fluids course that boundary layer separation can occur even for laminar non-turbulent flow (for high viscosity fluid). In this case, shown as ‘steady separation’ in the diagram below. ...
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What is the bare minimum of air density you need to fly a helicopter?

How high will a helicopter be able to fly before the propellers have not enough air particles to achieve lift? What is the minimum air density needed to achieve flight with a helicopter? Could you ...
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Drag Crisis and Terminal Velocity?

From what I understand, there exists such a concept known as the "drag crisis," at which an object's boundary layer transitions from laminar to turbulent and its drag coefficient decreases ...
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Would it be possible to reenter the atmosphere without a heat shield using a glider design? [closed]

Say my vehicle currently in orbit had large wings that would provide the necessary lift, would it be possible to bleed off the energy so slowly and gradually lose altitude that no heat shield would be ...
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Why increasing stagnation temperature in a nozzle reduces the mass flow rate ? (Physics explanation)

Let's consider a gas inside a reservoir at stagnation state $P_{i_0}$ and $T_{i_0}$. The reservoir is linked to a nozzle and the exit pressure is such that the nozzle is choked. Therefore the mass ...
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3answers
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Could a very fast fan moving room temperature air be heating instead of cooling?

I understand that a domestic fan on a warm day will cool a person down (I know this has something to do with wicking the heat away though I still don't fully understand the physics of the process) ...
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Is there a version of aerodynamics that incorporates and intergrates the complete physics of sound?

In learning about aerodynamics for aviation, it has struck me to what extend it is based on a variety of assumptions and presentations, that may one day have served to create a notion of what happens, ...
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Can turbulence be predicted from entropy?

Frozen water has lower entropy than liquid water. This is true for most solid/liquid transitions. Clearly a solid can't flow with turbulence ( although glass does flow over many years as can be seen ...
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Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled?

Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled? Usually pressure goes down with temperature.
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Why does a spear or a javelin turn in the air?

In videos of the javelin throw, the throwers consistently seem to grip the spear at the center of mass and launch it by imparting it an initial velocity. What causes the javelin to turn around an axis ...
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Swords and wing flutter

In order to retain structural integrity it is understandable that a sword has to be flexible enough to be able to absorb impact without shattering and rigid enough to not be bent due to it. Is this ...
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I'm confused when to use Bernoulli's equation and continuity momentum equation

Conflicts between Bernoulli's Equation and Momentum Conservation? 1). Is this equation compatible with any case? And how? 2). Isn't $\rho u$ from the derivation of the Bernoulli's equation a ...
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Does velocity always vanish at the trailing edge of an aerofoil?

In our fluids notes we derived the velocity field around a *symmetrical *Joukowski aerofoil by using a complex potential, and showed that, with the Kutta condition applied, the velocity at the ...
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Physical significance of infinite flow velocity at leading edge of flat plate?

In our fluids lectures we used a conformal map of a complex potential to transform a flow around a cylinder into a flow around a flat plate. We showed that the velocity of the flow was infinite at ...
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Modeling a 3D Wing — Joukowsky Airfoils and Prandtl Lifting-Line Theory

I am trying to calculate the distribution of lift over the span of a rectangular, non-swept wing with a (constant) Joukowsky airfoil cross-section. The wing is rectangular in the sense that the chord ...
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Lift coefficient for Magnus force

I have a project in a physics class where I need to conduct an experiment on the Magnus Force. On the internet I found that the equation for calculating the magnus force is : The problem is that I'm ...
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Drag coefficient for tilted plane

I'm trying to calculate the drag force for a thin rectangular plate with dimensions $L$ x $d$, like shown in the image below, with air flow (approximately) perpendicular to the plane defined by the ...
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Is the cross-sectional area of this object just the area of the 'top circle'? or do the angled sides and height matter?

The diameter of the top circle is $0.08m$, diameter of base is $0.06m$, and height is $0.018m$. I'm trying to calculate the drag coefficient of this object and hence need the frontal projected area, ...
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3DOF Rocket Dynamics for an LQR controller

I'm trying to define a simplified model of a rocket to implement an LQ regulator. What I need is the translational dynamics on the earth's inertial frame and the rotational dynamics in the body frame. ...
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1answer
117 views

Calculating Speed of bicycle down a hill or coasting to a stop

I'm working on trying to employ physics into a bicycle training app and I'm using the equations from http://gribble.org/cycling/power_v_speed.html to convert power (from the indoor trainer or power ...
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Calculating rotor inflow ratio in a helicopter rotor

Disclaimer, this is not homework. I am trying to determine the amount of lift force that a rotor on a toy helicopter actually produces. With some googling, I've learned that the formula for this is: $$...
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Are mach cone and vapor cone the same or not?

I have read numerous articles, claiming that Vapor cone IS NOT the mark that aircraft is passing "sound barrier", or, in other words it is not the visualization of Mach wave But I can't ...
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Wind turbine in water

I have a 3D printed wind turbine (I got the design from a research paper). If I conduct a particle image velocimetry experiment in a water flume instead of a wind tunnel, what should I expect as the ...
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What's the required area of a weightless plate in the air, to move only a set distance under given force in given time?

This discussion got started on Worldbuilding.SE; see the magical background there. At the root is a problem in pure physics, so I thought I would ask it here too. It concerns a witch who can walk on ...
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How does a ram-air parachute move forward?

I'm trying to understand the "physics" behind the flight of a ram air parachute, Do you know / how could I know, whether the main parameter that makes a ram-air parachute move forward is: ...
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How much pressure does it take to start an underwater gas fire?

It's recommended for underwater use of acetylene torches that you set the oxygen pressure to 90 psi, so that it creates an air bubble which allows the fire to get started. This made me wonder... do ...
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Does adverse pressure gradient increase with speed?

It is well known that adverse pressure gradient raise with AoA. For wing with fixed angle of attack does adverse pressure gradient at upper wing surface increase with speed? Im talking about subsonic ...
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Why high Reynolds number “implies” high airspeed?

Reynold number is ratio between (density,length,velocity) and viscosity, one Re number can has countless possiblities of different values of density,length,velocity and viscosity. I dont understand ...
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646 views

Does flow separation starts earlier at higher airflow speeds?

At same AoA,will flow separation starts earlier (point of separation more upstream) at higher airflow speeds (=higher air inertia) compare to lower airflow speeds? High speed airflow has more air ...
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Is inertia real reason for flow separation?

Consider airflow around square object, when an air particle A comes to the rear edge of an object. It is very logical that the particle would not turn at 90 degrees and follow back side of object, ...
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Verifying sonic condition at a throat nozzle

When I am reading lectures or exercises about Convergent-Divergent nozzle, many times the throat is supposed to be in sonic condition. But I don't see how scientists asses that sonic condition is ...
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Correlation between pressure gradient and curvature [closed]

We know that there is a region of high pressure at the leading edge of the vertex, and there is a region of relatively high pressure at the top of the airfoil. This sometimes makes me wonder is there ...
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Deriving Bernoulli's equation with the kinetic gas theory: Missing 1/2 factor

Inspired by Eugene Khutoryansky video about Bernoullis law (https://www.youtube.com/watch?v=TcMgkU3pFBY), I decided to put the thoughts and ideas from her video into mathematical terms. My derivation ...

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