Questions tagged [fluid-mechanics]

Questions relating to fluids at rest (fluid statics) or the forces and effects of fluids in motion (fluid dynamics).

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Calculate Power for pump

I did a Civil Engineering course some years ago and from my textbook I had a question on a pump with hoses. Unfortunately I haven't been able to find a solution to this yet. A pump feeds two hoses, ...
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17 views

Force exerted by a jet of water on a series of Radial Curved Vanes

Normally, when we calculate the force exerted by jet on vanes, we usually calculate the rate of change of momentum. The momentum change is calculated using the relative velocity of jet with respect to ...
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1answer
18 views

O-Ring Design for low pressure applications

I'm trying to figure out how to create a seal for a very low pressure gravity feed system. Essentially its a low pressure solenoid valve. Is there any equations to estimate the amount of force you ...
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29 views

Equation to calculate flow rate

Assume you have a solid walled sphere with an opening of diameter x. The sphere has volume 0.02 litres and has air at 1.4 bars. What general equation would be appropriate to correctly size the ...
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9 views

Minor losses in a header

I need to calculate the minor losses in a steam header. I have calculated the major friction losses. But I can't figure out how to find the minor losses since the header has multiple tappings and not ...
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1answer
26 views

What is the effect of different ways to adding liquid materials into a mixing tank?

I am working with body wash products and there is a problem happening with the mixing process. I use a 5000-liter tank to mix all the liquid materials including water, surfactant and preservatives. ...
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2answers
84 views

From a mechanical point of view(Physics/Engineering) why are Front-Load washers said to clean/wash better than Top-Load washers on average?

Which cleans better? Is it just marketing or do they really clean/wash better due to some physical property or the way they work, I am asking how do they if they do? N.B I do not intend to indicate ...
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14 views

Comparing power requirements of centrifugal pump installations

Hi, I am stuck with a question related to the centrifugal pumps. There are two centrifugal pump installations and it is asked to compare the power requirements for two installations. As in Pa>Pb or ...
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18 views

Is it possible to reduce energy consumption of air separation unit by using single column rectification process?

Is it possible to reduce energy (Joule or KW) consumption of air separation unit by using single column rectification process instead of double column rectification? Is there any examples that this ...
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35 views

Most efficient turbine for harnessing energy from bidirectional air flow?

I am currently working on designing an oscillating water column as part of a project. In summary: OWC are devices with a semi-submerged chamber or hollow open to the sea below, keeping a trapped ...
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1answer
19 views

Can a “surface drive” propeller be submerged if induced supercavitation reduces water surface area?

Assuming induced supercavitation (like Supercavitating torpedo and Juliet Marine Systems Ghost) reduces water surface area does that reduce friction enough to submerge a surface drive propeller ...
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14 views

Submerged gate hydrostatics question

I know I must integrate this problem, but I am confused as to what exactly I supposed to integrate. Could you help me with the method for solving this problem? dF = rho * g * y
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1answer
40 views

Calculating mass flow rate of a scramjet engine?

First post here. I'm an undergraduate ME interested in fluid mechanics. I came across scramjets and I was interested about the engine. I want to calculate the mass flow rate of the engine and I made ...
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1answer
23 views

Pressure Coefficient with a Minima of 0 on Compressor Airfoils in Cascade

I am a relatively recent BSME graduate working on reproducing the results of a technical paper to strengthen my ANSYS CFX skills. The paper is "Effect of Section Thickness and Trailing Edge Radius on ...
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1answer
30 views

How to infer from the volume fraction function whether a flow is transient or steady?

Hello dear engineering community. I have a specific question about multiphase flows. I was wondering if anybody could help me with it, please. Assume, I have a one dimensional water-air flow. Air is ...
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1answer
23 views

How to calculate the viscous damping coefficient given drag force

Force due to drag at low velocities, is equal to some constant times negative velocity $$F_{d}=-c_{1}V$$ The viscous damping coefficient equals decay constant divided by 2 times mass $$\gamma = \...
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1answer
34 views

What Is The Liquid Depth Inside The Tank?

I know that $P_{total}=P_{gauge}+P_{atmosphere}$, so $P_{gauge}=P_{atmosphere}-P_{total}$ $P_{atmosphere}=101.325 KPa$ and $P_{gauge}=0.2 psig=1.38 KPa$. $P_{gauge}=(0.8 \times sin{30})(900)(9.807) -...
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Question with regard to spacex raptor engineand other full flow staged combustion engines

The diagram linked is unofficial but I've looked at other diagrams which are similar. The coolant is pumped in at a high pressure much higher than the maximum chamber pressure of the rocket the ...
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1answer
41 views

Fluid Mechanics - Fluid flow

I have answered the following questions, however I’m unsure if they’re correct. 1.) For this question do we consider gravity force, I have used it but I’m not sure if this invalidates my overal ...
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12 views

Efficiency of pump on VFD?

If I'm replacing a control valve with a VFD for a centrifugal pump, how do I predict the pump efficiency? I've got a pump curve which tells me my pump's efficiency at at a given flow or a given dP ...
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37 views

Grad student needing help with a fluid mechanics issue in project

BROUGHT OVER FROM PHYSICS STACK EXCHANGE As the subject states I have hit a wall in a fluid mechanics associated problem in designing an experiment for my grad project. Long story short, I'm an ...
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1answer
36 views

Does turbulent river flow classify as uniform?

I found this meme in a facebook group on engineering concepts: I selected A (steady and uniform). In selecting A I assumed the width of the river to remain constant along its path and no parameters ...
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10 views

What version of ANSYS is useful for simulation flow in a fin heat sink?

I'm interested in learning flow simulation in ANSYS and have found several tutorials. However, none say which version of ANSYS to download. The options are "Discovery Live Student", "Discovery AIM ...
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1answer
72 views

Could boiling water inside a semi-enclosed pipe be a low-cost method for a silent marine propulsion system? (redesigned)

I am wondering if boiling water that is trapped inside of a semi-enclosed pipe would be a low-cost method of creating an underwater thruster that would function as a silent marine propulsion system. ...
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1answer
33 views

Laminar flow hood/air straightener

I was looking at laminar flow filters to aid in my mycology work I'm doing. Most filters use an aluminum extrusion with fins. I figured the options out there are pretty expensive for what you get and ...
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1answer
35 views

What pressure drop is needed to get 15-20 gpm?

Scenario: There's a 1 inch, rubber hose, with fluid flowing in it at 75 psi. The density of the fluid changes (but I'll just be calculating with a specific known density, 8.35). So, I want to get the ...
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33 views

water pump problems

I am presently facing a problem in water plant . In a tank there are four pump placed at equal distance named A B C D .in this arrangement A and D positioned at near corner of the tank . I started ...
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15 views

How to minimize temperature increase caused by compression of a cryogenic liquid in a multistage high pressure turbopump?

The cryogenic fuel I'm using is methane at 100 K and 300,000 Pa. Based on my calculations, after compression, the pressure is 55 MPa and using the ideal gas equation the temperature is approx. 800 K. ...
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1answer
53 views

How can I connect F=ma to Drag=1/2*Cd*(rho)*V^2*A?

I previously posted a different question that was very vague. I have kept working on the problem, and now I have a different question. Please let me know if I should have just added it to the old ...
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11 views

Which version of the Kozeny-Carman equation is valid?

I am learning fluid mechanics, and I've come across the Kozeny-Carman equation for a packed bed in laminar flow conditions as: $$\frac{\Delta P}{L}=\frac{150\bar{v_0}\mu}{\phi^2D_p^2}\frac{(1-\...
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55 views

What is this weird upside down U shaped pipline for?

There is this tall upside down shaped U pipe near a sugar refinery on Maui and I can't figure out what it's for ? I've also see these in other industrial areas near salt flats.
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1answer
10 views

How to ensure uniaxal and uniform force application on uneven samples using pressurized fluids

I am trying to apply a compression force to samples using air. I do not want to directly apply my loading since my samples are irregular. I do not wish to process them with a flattening step. I hope ...
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1answer
76 views

Heat Transfer in Different Wire Configurations

I am trying to create a program which estimates the final temperature of a magnet made of copper wire. I have different configurations in mind, but I will start off with a straight square wire with a ...
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22 views

Static charge, PVC pipe and water

I know it's possible for a PVC pipe to develop a staic charge due to fluids flowing through them. This is a twist on that idea. Can a sealed length of pvc (say 3.5 feet in length) - tethered below ...
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2answers
37 views

What is up with the spaced rudders on the SMX-31/Barracuda?

You can see it in the video here for the Barracuda: https://youtu.be/_NZKyvQVRd0?t=124 And here's a pic of the SMX-31: http://www.hisutton.com/images/Fr_SMX-31_cutaway.jpg What are the advantages ...
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2answers
53 views

Efficiency of TurboJet engines with nozzles

As per Bryton Cycles, most of TurboJet engines' Thermodynamic efficiency should be around 40%. Rest of energy gets rejected as waste heat in exit gases of after the turbine. But if these hot gases ...
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39 views

Can someone please give me a hint on how to draw velocity triangles for this specific inward flow reaction turbine problem?

I'm trying to calculate the hydraulic efficiency for this turbine by using the formula: E(hyd) = (VwU)/gH where Vw= Velocity of whirl at inlet, U=velocity of runner at inlet, H=Given Head, and g=...
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1answer
21 views

Pushing fluid through microfluidics

my team is working on a project where fluid (mostly water) need to be pushed through small channels (like small pipes) in order to reach larger reservoir. We were considering using air to push the ...
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3answers
32 views

Design of Gating & Runner system in Gravity Die Casting

How to design gating and runner system in permanent dies so that material flows smoothly throughout the design without spilling back from the gating channel. What should be the shape of gating system ...
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29 views

Is there some temperature at which all “5w” oils should have about the same viscosity?

Is there some temperature at which all "5w" motor oils should have about the same viscosity? (5w-20, 5w-30, 5w-40, 5w-50, etc.) I am looking for SAE or ASTM wording or chart that says it straight ...
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1answer
66 views

What is the axis of a pipe?

Sorry, it seems like the answer to this question is just a quick google search away; but I have not found a page defining what the axis is. My guess was that the axis of a piple is the imaginary line ...
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26 views

Low pressure Diesel pumping with High pressure Gasoline pump?

We are in desperate search of suitable pumps for one of our applications. We need to be able to pump Diesel fuel in a range going from 5bars to 125bars. To do such thing, I've been looking at Bosch ...
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13 views

How to increase pressure in an axial fan using additional inlet and outlet vanes?

I have a fan used to push hot air out of a storage room through a pipe. For this purpose I therefore chose an axial heatsink fan with high static pressure. I discovered that it's possible to 3D print ...
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2answers
39 views

Measuring viscosity with tools other than viscometer

I would like to measure viscosity, but do not have access to a viscometer. If possible, I would like to avoid having to purchase one. I have access to many other flow measuring devices, including ...
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33 views

How to calculate flow rate and direction in system with multiple blowers

I have an odour control system where foul air is being extracted from multiple sources and then pushed into a scrubber vessel. Normally, all my designs look something like this: https://ibb.co/...
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21 views

How much force is required to push a liquid out of a syringe? [duplicate]

It's about 3D bioprinting and I need a calculation on how much force is required (pressing on the syringe piston) to push out the solution with known density. Moreover, there are few more ...
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1answer
30 views

Supersonic isentropic flow

how to know if a deflection in a supersonic isentropic flow causes compression (oblique shock) or expansion (Prandtl-Meyer expansion) Thanks in advance. an example of a problem that is related to my ...
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20 views

Couette-Poiseuille flow between non-parallel plates

I have a Couette-Poiseuille flow (both flows combined) where the plates are not parallel. So h, the thickness of the flow, changes along the x axis. Can I use a mean h to calculate the viscid stress?...
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1answer
33 views

What's a good way to equalize pressure between 2 spaces without allowing gas exchange under normal circumstances?

I have a reaction chamber where gasses are injected to maintain a certain mixture. The container is sort of like a bell, where the bottom is submerged in water to make a seal. The issue I have is ...
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38 views

Difficulty to reach Mach 1 by blowing into a small converging-diverging nozzle?

I'm learning about the basics of converging/diverging nozzles in my thermodynamics class, and it has me curious. Could you theoretically blow into a tiny converging/diverging nozzle and break the ...