Most Popular
1500 questions
12
votes
3 answers
Do I need to worry about galvanic corrosion when inserting a steel bar through aluminium?
My design uses a round steel bar inserted through a hole in an aluminium component with a tight fit (no movement). The operating environment is dry, 20-40°C.
Do I need to worry about galvanic corrosion, and if so how long will this last before…
jhabbott
- 5,970
- 7
- 30
- 63
12
votes
2 answers
Does a Faraday cage effectively act as a notch filter?
In reading about Faraday cages, I have found that most "real world" designs incorporate multiple layers of mesh. For example, this article from the National High Magnetic Field Lab discusses several different shielded rooms built of varying…
user16
12
votes
3 answers
Which turbulence models are suitable for CFD analysis on a streamlined vehicle body?
Many commercial and open-source CFD codes implement several closure methods for the non-linear convective acceleration term of the Reynolds-averaged Navier-Stokes (RANS) equations. Common methods (also known as turbulence models)…
Paul Gessler
- 822
- 12
- 16
12
votes
4 answers
Why is oil used as the lubricant in power generators, while water is the most available, cheapest and accessible lubricant?
The lower viscosity of water reduces friction. Besides, the water can transfer heat way better than oils. So why not use water as a lubricant in wind or hydro turbines, especially on equipment which is operating in the ocean ...
It seems to be a…
Sam B
- 334
- 1
- 2
- 10
12
votes
1 answer
How can Pareto Analysis help solve engineering problems?
Attach is a Pareto Diagram with Number of Defects in Y-axis vs Causes in X-axis for an engine overheating problem. How can this Pareto diagram help an engineer solve the engine overheating problem?
Reference:
Pareto analysis
Mahendra Gunawardena
- 7,135
- 6
- 27
- 68
12
votes
1 answer
Insufficiently constrained structural model in Ansys
I want to analyze this model that is stressed and deformed. I fixed the lowest of points in the x, y, and z directions, and I pulled top of points upward (y direction). When I run the model in Ansys I got the following error:
Check for…
Bae
- 121
- 1
- 3
12
votes
5 answers
Low cost, moderately accurate water depth measurement
tl;dr: After an extended conversation with an old-timer, I realized a few things:
The single most valuable measurement for the majority of people will be water-depth-in-well.
The second most valuable will be water-flow-from-well.
The "bubbler"…
Peter Rowell
- 243
- 2
- 8
12
votes
1 answer
What are the lightest springs?
I am wondering if there is a spring strong enough and light enough to inflate an airtight membrane so that it floats at Standard Temp & Pressure.
As an example, a 10cm cylinder would displace just under 1 gram of air, but a cylindrical spring would…
feetwet
- 1,757
- 2
- 15
- 41
12
votes
3 answers
Exploiting fluid dynamics for the optimal design for gas mixing in a furnace
Background
This is the standard design for a thermal furnace used in the Clauss process, which converts H2S to SO2. The main problem with the furnace is that gas mixing is rather poor and results in only a 60% conversion rate. This in turn…
22134484
- 331
- 1
- 6
12
votes
2 answers
How long does it take for dust to settle out of the air?
In order to make this a manageable question, let's add a few simplifications.
The dust particles can be well described as uniform spheres of radius $R$ and density $\rho$.
The space is enclosed and there is no bulk flow, i.e the air is still in…
Chris Mueller
- 6,416
- 2
- 28
- 54
12
votes
4 answers
Will more electricity be generated by using a lens to focus sunlight onto solar cells?
I have been wondering about this question for quite some time. Assuming an ideal case, the energy from photons hitting solar cells is converted into electric energy as described by the equation:
$RI^2t=W\equiv E=\hbar\nu$
where $\nu$ is the…
TBBT
- 223
- 2
- 5
12
votes
2 answers
How do I solve an optimal control problem where the dynamics depend on some function of the state?
A typical optimal control problem with state $x(t)$ and control $y(t)$ can be expressed as $$\max_{x(t), y(t)} \int_0^{t_1} f(t,x(t), y(t)) dt$$ subject to $x'(t)= g(t, x(t), y(t))$ and boundary conditions for $x(t)$.
I want to solve a problem that…
Daniel Wills
- 121
- 3
12
votes
5 answers
What is the difference between pressure and stress?
Since the units are the same ($\frac{N}{m^2}$), what's the difference between pressure and stress?
user133
12
votes
2 answers
Why do earth cuts sometimes have steps on their walls
A neat image from Wikipedia:
There're clearly visible steps on the cut wall. This makes the cut wider at the top and so requires more work so those steps have some serious reason behind them.
What's the purpose of these steps?
sharptooth
- 2,099
- 17
- 27
12
votes
5 answers
Should we protect our AC's outdoor unit from sunlight?Does it increases the durability of an AC and its refrigerant if it is well shaded?
My AC outdoor unit gets direct sunlight (no shading whatsoever) from morning to noon. Temperature normally soars up to 40 degree Celsius (I am from India). I have two questions:
Is this bad for the AC's refrigerant, does it lose efficiency over…
Paran
- 245
- 1
- 2
- 6