Questions tagged [hydraulics]
Questions about the flow and use of fluids.
157
questions
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38 views
Calculating discharge from a reservoir as the head of water decreases
Due to the dry weather we've been experiencing in the UK I need to calculate the discharge rate from some reservoirs for work and how the dropping water level will result in a reduced head and so a ...
2
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2answers
32 views
HPU minimum oil temperature
Two different HPU systems in different locations with slightly different oils Chevron Ranco HD 68 and HDZ 68 have the same minimum oil temperature 55. Their flash points are are 455 and 414 F ...
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0answers
40 views
What's the most efficient air compressor to reliably deliver up to 15 litres per second at 10 bar? [closed]
Suppose I wanted to continuously supply up to 15 litres of air per second, compressed to 10 bar - what would be the most efficient type of compressor, i.e. the type requiring the least energy input in ...
2
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0answers
39 views
Help calculating discharge rate from a reservoir as the water level drops?
I could do with some help calculating the discharge rate from a reservoir and factoring in how that flow will decrease as the head of water decreases.
The information I have is:
Maximum height of ...
2
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1answer
46 views
How does hydraulic pressure booster works?
This photo shows hydraulic booster used in HPHT Hydraulic Press. I could not understand its function.
How does this pump boost the hydraulic pressure ? Thanks.
2
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1answer
44 views
How to compensate for losses in a hydraulic system?
I have an engine ( 72240 kW... ) , probably the biggest internal combustion engine in the world and this engine has no camshaft. Instead it has an hydraulic system which controls the combustion, the ...
0
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0answers
30 views
Working out location of a hydraulic jump
This is the question I am working on:
And here is part of the working i don't understand:
I don't understand the process of plotting the profile - the little crosses marked on the diagram, how do ...
1
vote
1answer
42 views
Component selection type for fluid-mechanical system
I am creating an enclosure and need to get a water supply through a plastic wall inside to the core device. I imagine this water line will be a flexible tube and will screw on or snap to an adapter on ...
3
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0answers
62 views
Hydrostatic transmission to directly translate movement
I have been thinking about small hydrostatic transmission to directly translate movement of stepper motor (NEMA 17-23 size, geared with 3:1 or 5:1 ratio).
My design currently involves 2 identical ...
1
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1answer
24 views
What is the side way force on a flat membrane place perpendicular to the flow of current on one side, and stagnant water on the other
So basically imagine a plate being placed parallel to the direction of flow of water with water flowing with a certain velocity on one side of the plate and on the other side it is almost stagnant. ...
0
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2answers
74 views
Pumps' geometric similarity
Given two pumps that are similar :
$H_1=70-1.41x10^{-3}Q_1^2$
$H_2=100-1.1x10^{-3}Q_2^2$
Find the geometric scale :
$\frac{D1}{D2}= ?$
I am also given maximum efficiency = 1.
I tried solving but I got ...
0
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1answer
57 views
Boundary layer thickness decreases as fluid velocity increases, so why is the boundary layer thicker in the turbulent region for higher velocities?
I am modelling transitional fluid flow over a flat plate, and investigating the effects of free stream velocity on boundary layer thickness. From what we have been told, increasing free stream ...
1
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1answer
43 views
Why is the head loss in submerged pipe is 0
Looking at this question :
Point C head loss is 0 according to the author
Bottom right
Can’t understand why , any good explanation for this claim ?
Look at page 33 at the top
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1answer
20 views
Will decreasing a pump's flow rate decrease the NPSHR?
I have a small open hydraulic system and I simply need to circulate hot (85C) water from the bottom of a reservoir back into the top at ~4GPM. At its lowest point the system has only 3ft of static ...
1
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1answer
57 views
Running Hydraulic Pump with High Torque Motor
It's my understanding that hydraulics are merely a means of gear reduction to move a given object. So then I'm wondering why I can't find a formula or way to determine the following issue:
I want to ...
3
votes
3answers
106 views
I cannot properly understand the “pressure” referred to in Bernoulli's Principle despite my efforts
I get that with Bernoulli's Principle an increase in area = a decrease in velocity = an increase in pressure. I also understand the concept of pressure being force per unit area.
My difficulty is with ...
3
votes
2answers
79 views
How is high static water pressure avoided in municipal water systems?
Most cities get their water supply from local sources (springs, rivers, lakes) so the pressure in the system is never more than what is produced by the pumps.
But some cities get their water from ...
1
vote
1answer
58 views
Low maintenance device to trade flow rate for lift height?
Is there a compact device which can trade flow rate for lift height without too many moving parts?
My particular application is a 10 meter deep and 10 centimeter wide well with shallow water level, ...
1
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1answer
54 views
Hydraulic system dynamics modelling
I'm trying to mathematically model an actuation system and it comes down to relating the pressure across the pump and the actuator as shown in the picture. Assuming no friction in the pipes and the ...
1
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1answer
66 views
Circuit to provide position control for double action hydraulic actuator
I was wondering how to construct a hydraulic circuit to control a hydraulic double acting piston/actuator enabling the electronic control of the piston extension. I have found the following pneumatic ...
1
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2answers
42 views
Hydraulic energy recovery for high-pressure, low flow (non-steady state) conditions
What would be the best way to implement hydraulic energy recovery while de-pressurizing a pressurized volume of silicone oil initially at 1500 bar. Can a piston pump be concievably repurposed as a ...
2
votes
1answer
55 views
Running a hydraulic pump below minimum RPM
If I had a pressure compensated, hydraulic piston pump, how might the performance look in terms of pressure if I were only looking in the regime of 0 RPM and the minimum ratedRPM?
I.E If a pump was ...
0
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1answer
35 views
What voltage are these hydraulic valves and how to I control them?
I am building a new control system for an injection moulding machine, the last part I am trying to work out is the main pump.
It has two proportional valves on the output, one labelled throttle valve ...
3
votes
0answers
37 views
Volumetric oil pump efficiency goes up when viscosity goes down?? Strange behaviour
Riddle me this : we are driving an external gear pump (this kind) at a fixed RPM.
At start, when the oil temperature is low (and viscosity high), the volumetric flow is much less than when the oil ...
0
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1answer
54 views
Why would these hydraulic cylinders have 3 large connections?
I am trying to work out how a recently acquired Arburg 220-90-350 from 1982 works so that I can build a new control system and get it working. It's a direct clamping machine with no toggle.
The ...
0
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0answers
32 views
How to get this hydraulic system working and help identifying parts and their function
I have recently acquired a 1982 Arburg 220-90-350 injection moulding machine, mainly just as a hobby to further my knowledge on injection moulding machines and control systems as I plan to modernise ...
0
votes
1answer
35 views
Brake selection problem
I have a quick question guys. I am gonna select a brake but I am not sure.
A Crane Hoist motor has a rating of 300 HP and maximum speed of 1800 rpm. This motor is attached to a gearbox with a perfect (...
1
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1answer
31 views
Effect of flow through a static hydraulic pump on its RPM
What happens when fluid flows through a static hydraulic pump? Will there be a negative RPM to impede the flow?
By static pump, I mean a pump with initial RPM = 0.0 and is not driven by external ...
-1
votes
1answer
162 views
Head loss for T junction diverging water pipes
I am writing to ask for help with a T-junction pipe problem. Attached picture shows the pipe configuration. The schematic shows a large pipe with ID 16.5mm and smaller 4mm ID tubes connected to it. ...
-1
votes
1answer
42 views
Hydraulic lift connected to two pistons
I just finished a problem, and got the correct answer, however I am confused on one of the mathematical operations that must be performed in order to get the correct answer.
The problem is as reads: ...
2
votes
2answers
64 views
Stop Spa-to-Pool Siphoning Thru Spa Pump
I have a partially above ground Spa and an in-ground pool. When the spa is filled to spillover with pumps off, water siphons through the spa pump and into the pool until the spa water level drops ...
1
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1answer
23 views
Does a single-wheel brake intervention from ESC cause one wheel to be not brakeable by the driver?
Source: https://www.kfz-tech.de/Engl/Buchprojekte/HBremse/ESP3.htm
Firstly, I don't know if this is the right StackExchange, but I will try nevertheless.
Above I posted a picture of the hydraulic ...
-1
votes
1answer
88 views
What specific technical concerns exist for China's Three Gorges damn on the Yangtze river?
Recently, many people (specifically geopolitical and financial analysts) have pointed out that there is a serious concern about China's Three Gorges Dam breaking and causing catastrophic flooding that ...
0
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3answers
92 views
Replicate stepper motor with gasoline engine
For those unaware of what a DC stepper motor is, it boils down to an electronic motor where the rotation can be precisely controlled, i.e. you can control the rotation of the motor in fractions of a ...
2
votes
1answer
334 views
hydraulic Motor/pump minimum speed
I have seen in many data sheets of Hydraulic Gear motor a spec called : "Minimum Speed = 450 RPM" ( 450 is an example)
here is a capture from the linked datasheet below :
In your experience ...
-1
votes
1answer
146 views
How would you go about calculating the force required for an actuator to lift a bridge?
I have been trying to come up with the optimal way to calculate the force required for an actuator to be able to lift a bridge 90 degrees. (A drawbridge) The actuator is placed as follows: (The bridge ...
2
votes
0answers
34 views
How do I calculate Pressure drop across relief valve and then force on piston?
So, I'm designing a basic downhole hydraulic tool cutter of an OD = 5 1/2 in., and my tool contains a relief valve and a piston. I am trying to calculate pressure drop across the relief valve so that ...
3
votes
0answers
35 views
What domestic water valve is least likely to jam over time?
I'm doing some work on a domestic water system, mostly 15 or 22mm copper pipe with compression fittings.
The work includes replacing various stop-cocks and drain valves some of which are probably 30 ...
1
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0answers
80 views
How many kWh this turbine would generate?
My grandfather and I are running some experiments down the river, however we don't have expertise in engineering so I bring up this question to the community and hope someone could help.
How many kWh ...
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0answers
66 views
Reference book for hydraulic systems design
I'm looking for a good reference book on the topic of fluid dynamics/hydraulics systems engineering.
I'd like a reference for simlpe/estimate calculations on things like major losses (pipes), minor ...
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0answers
24 views
Water distribution through N x Needle orifices
Consider a water distribution setup consisting of a feeder line blocked at one end but having 100 needle outlets all the same size. The feeder line cross sectional area is much greater than a needle ...
1
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1answer
26 views
Bi-directional liquid transfer
I'm attempting to design a system that consists of 4 secondary(ABCW), 1 primary(Film) tank, and a pump. The idea being to Transfer the contents of each secondary tank to the primary one, then back to ...
1
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1answer
116 views
Hydraulic Brakes - Why motorcycle brakes more powerful than bicycle brakes?
I was wondering why motorcycle brakes have so much more stopping power than bicycle hydraulic brakes (Than can be found on mountain bikes for example).
The rotor has a bigger size which gives better ...
1
vote
1answer
59 views
Distribution of water through a pipe network
I have a network of stainless steel pipes that are distributing water throughout a building.
I know the flow rate of water entering the system is 600 IGPM, but am unsure of how this water will be ...
1
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0answers
1k views
How to calculate the flow rate of a gas through a pipe?
I am trying to calculate the flow rate of Nitrogen through a cylindrical pipe.
I only need a ballpark value, and the only information I have is the inlet pressure as 15 psig (assuming the same ...
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votes
2answers
79 views
The Cavitation Problem
I'm new here and would like to ask where the cavitation would happen in my design.
Thanks
0
votes
1answer
307 views
Determining steady flow between two reservoirs with two different pipes in between
Two reservoirs are connected by two pipes with different diameters in series. The elevation of Reservoir A is 40m and Reservoir B is 35m to respective water surfaces. The first pipe is 500 m long with ...
1
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1answer
41 views
How do I Calculate Pressure at Multiple Points in Time while Filling a Container with Water?
Say I have a container completely full of water with a volume of 3000 gallons and I'm filling this container with water at a rate of 8.2 gallons per minute, it's already full at 200 PSI, how do I ...
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0answers
92 views
Head loss from rectangular slot orifice flowing up?
For sizing purposes I'm trying to calculate head loss for a level spreader outlet for water, where the water is being supplied from below by pressure. It's essentially a reverse slot drain—instead of ...
1
vote
1answer
64 views
Deriving the ideal equation for sluice gate problems - incompressible inviscid fluid
I'm trying to figure this problem out, i know the correct answer, and i know the method, but for some reason i'm missing something and i'm just not getting there, any help would be greatly appreciated....
