We were trying to do a vibration test of compressor assembly in a electrodynamic shaker at an external lab. Initially, the test lab personnel did a sine sweep from 5 to 1000Hz at an input acceleration of 1g and a sweep rate of 1 oct/min. Thereafter we need to do a resonance dwelling at the...
I am referred to a gear (helical) rattle under both unloaded and loaded (?) condition. The gear box is that of a screw compressor (positive displacement). I can understand rattle under unloaded condition, due to a probable higher dynamic torque, which would aid in the separation of the gear...
I was trying to measure the axial natural frequency of a male rotor on its bearing(antifriction) in rest ( load equiavlent to its normal operating condition). I have prediction value (just the first mode, which is very similar to SDOF system) based on bearing stiffness and this is 386Hz. The...
I have a drive train comprising of a motor (4 Pole 3 phase induction motor, 50Hz), resilient coupling and a compressor (screw compressor- 4 male lobes / 5 female lobe combination). These compressors make a strong modulating / beating noise, which gives a perceptional feel that something is...
I have a drive train comprising of a motor (4 Pole 3 phase induction motor, 50Hz), resilient coupling and a compressor (screw compressor- 4 male lobes / 5 female lobe combination). These compressors make a strong modulating / beating noise, which gives a perceptional feel that something is...
thread384-207749
Dear All
I was referred a noise problem with 3cyl engine driven (Deuz)compressor. On analysing the spectrum, the engine firing frequency and its harmonics are contributing to the overall levels, as one would expect. The engine has a muffler , which is sourced outside. I am...
Dear All
I was referred an abnormal noise arising out of a motor driven screw compressor (4 lobe compressors) during unloading. Typically these compressors run at the same speed (1450 rpm in this case) for loading and unloading conditions. The operating pressure of these compressor under...
My collegue is involved on a problem identification of a "belt loosening / slippage problem leading to failure" in a motor (11kW power) driven screw compressor after a few (20 - 30) hours of operation.
Is there anything else he needs to consider apart from the static design, contact angle...
Hi All
I am looking for a test equipment, which could measure the dynamic torsional stiffness of couplings. If you have come across the same, kindly let me know.
Regards
Jeyaselvan
thread384-165178
How do we hand calculate the static load distribution (with known mass, inertia & CG) at each mount (know stiffness and locations relevant to CG) support manually for a 4 mount support system? Static indeterminate for more than 3 supports and force & moment balance does not...
This is primarily concerned to the coupling selection / design. Usually, we do the static torque design estimations (take some safety factor!)and free torsional analysis to ensure that we are away from opertaing in resonance. The coupling manufacturers tyically gives the peak torque as twice the...
I am working for a compressor design & manufacturing company, wherein we use disel engine driven compressors(screw compressor). Usually the drives are mostly 6cyl and few cases of 4 cyl engines. Recently we had a new application with 3 cyl engines.
We are observing a lot of pitching vibration...
I was trying to estimate the torsional response of the drive train comprising of a compresor driven by a four stroke four cylinder diesel engine compressor. The model is based on eigen value / vector and modal summation approach.
I have obtained the torsional - crank angle informations...
Is is required to estimate the mounted resonant frequencies (the first translational and rotational modes) while doing a isolation design apart from the transmissibility requirements? This, I believe, could possibly eliminate any coincidence with the excitation frequencies. I am analysing a...
Is there some commercial instruments available for non intrusive shaft torque measurement? Primarily looking for shaft torque measurement in Motor/Engine-Coupling-Compressor drive train.
I am already looking into strain gauging with telemtery based systems. Anything more ? Thanks
I have observed that most of the structures (structures which responds to vibration & radiate noise) concerning NVH have very high global stiffness. I believe they are primarily intended to make the structure more stiffer by have lesser modal density. This effects in less modal responses thereby...
I am trying to understand the limits in resolving two sources (located say within the acoustic wavelength). If we assume that the sources independently generate acoustic waves of say 100Hz & 150Hz is it really possible to decipher the sources with p-p sound intensity method?
I am sure that your...
I am designing a Helmholtz resonator for reducing the intake noise of screw compressor. As put forward by Mr.Rob45 in earlier threads on similar subjects, no reference has been given in text books available for actual sizing. I initiated the design such that the product of resonator volume(in...
In a compressor test rig, we intend to use an automated throttle valve to load the compressor at finer resolutions of say 0.05 bar or better at working pressures of 5 to 15 bar.The pressure downstream of the valve is near atmospheric. Currently we are using a 1" ball valve with pneumatic...
