I have a centrifugal fan directly coupled to the motor shaft. For centrifugal fan, since the air is pulled into the middle of the fan and is flung out due to centrifugal force, the thrust should be pushing against the motor shaft. Maybe I'm mistaken, because I've heard the other way around...
Hello, I inherited a Flowserve pump without any information about the pump.
FLowserve WM inline centrifugal pump
Size: 2x3x12
Head:230'
Capacity:50
RPM: 3505
I've asked Flowserve twice about the pump curve and NSHr, but didn't get any response. I'm trying to design a water tank to create...
Hello, I have a motor that is connected to a dyno with big blowers. Most likely those blowers will dominate the noise for the entire system. I want to measure the dyno with blowers first (background) and then measure the total system (tot). To get the motor sound pressure level (source), can...
Have a few questions about the bearing configuration for vertical motors. Just in case, DE - drive end. NDE - non-drive end
1) Typically, I've read that the NDE bearing takes the thrust load, and the DE bearing is more of a guide bearing. Why is that? Can DE bearing take the load and NDE...
Hi, I have a question about the machined steel plate I received from overseas vendor. The entire plate has a medium grayish finish. I tried to scrape it with a screw driver, and I don't see anything flake off, so I don't think it is a primer. I have 2 questions:
1) After you machined a...
I'm looking into bonding NiCuNi magnet to steel plate using acrylic adhesive. I have 2 questions about surface preparation:
1) In the past, when I get steel plate from overseas, they usually have primer. Should I request bare metal with oil coating? My preference is coating of some kind...
For the same fan OD and rpm, how can we estimate the fan performance (CFM, SP and BHP) when we vary the blade width, like 1" vs. 10"? Fan laws don't seem to account for that.
I recently looked up a compression fitting: 1/8" tube fitting x 1/8" male ISO parallel thread. The problem I have is with the 1/8" male ISO parallel thread part. I bought the part and I measured the thread OD and it's a little over 3/8". I got the same thing when I downloaded the 3D model from...
Hi, guys, for a centrifugal fan curve, you have 2 end points (0 CFM, Max SP) and (Max CFM, 0 SP). I though I could use the Bernoulli equation to verify it, but it's not working. Maybe someone can shed light on what I'm missing. Max SP + 1/2 density * (0 CFM/area)^2 = 0 SP + 1/2 * density *...
I'm looking into the frictional loss of fluid between a rotating disc and a wall. Many works have been done for rotating cylinder inside a stationary tube, so I was trying to use that to come up with an equation to estimate the frictional loss.
s - the uniform gap between the disc and the...
Hi, there. I'm trying to use a VFD for my motor. I was reading VFD spec and it says
maximum current/power with 115% overload for 60 seconds; every 10 minutes
Does this mean I can operate VFD at 115% for 1 minute and 100% for 9 minutes or 115% for 1 minute and 0%/no load for 9 minutes?
I'm reading up on this article about heat sink calculation. Link
I'm confused about the Reynold's number equation. Eq 10.
It shows Re = (rho)(V)/(mu)(b)(b)/(L) b is the fin spacing and L is fin length.
The author treated hydraulic diameter, Dh, as b^2/L. I don't really understand why. I...
I recently worked with a HVAC personnel. He told me that, if you have a lot of refrigerant inside the condenser coil, you can reject the refrigerant inside the condenser coil by covering up the condenser coil with cloth while the fan is running or shut the fan off. (basically heating up the...
Hi, i'm fairly new at the pump curve stuff. I just started looking at a PD pump curve for my working fluid at 60C. If my fluid goes down to 40C, will the curve stay the same or shift toward left? PD pump should have a predictable flow rate at given pressure/speed, so even though colder fluid...
I'm going over the P-h diagram for R-134a. I was wondering how I can explain "flash" in P-h diagram. The refrigerant starts in the liquid state, but, through pipe resistance, head lost...etc, the refrigerant will flash off. I just don't know how to explain that phenomenon in P-h diagram.
I have 2 questions about an evaporator. Please correct me If I'm wrong. This is just my understanding.
1) If an evaporator (hot air/r134a) has a max rating of 10 kW, how do they come up with that value (Q_dot)?
2) For a given system, the evaporator can be pair up with a 10 kW heater, but...
Hi, it has been years since I last worked with refrigerant. I was looking up on enthalpy for r-134a. In my text book (Moran and Shapiro 3rd ed), at 40C, hf = 106 kJ/kg, hg = 268 kJ/kg. I came across this DuPont Suva HFC-134a technical information and it has hf = 257 kJ/kg, hg = 420 kJ/kg at...
I have a fabricated enclosed water jacket vessel (internal dimensions (~25" ID, 25.5" OD and 30" length)). The water jacket skin all around is about 0.38" thick and it has to withstand ~ 3 bars of water pressure. Customer wants to use regular tap water without additives. The water jacket has...
My original problem is to find the torsional frequency for a rotor cage. I first looked into the torsional frequency for 2 discs (J1, J2) and 1 massless rod in between (standard textbook problem). Using torsional stiffness equation, kT = G*J/L, I was able to find my torsional frequency of the...
The problem I have is finding the natural frequency for a cantilever beam mounted on a vibration isolation pad. I first modeled a cantilever beam fixed at one end and found the natural frequency using the standard formula Link Based on the frequency, I simplified the system into a mass spring...
