Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Dynamic Response


Optimum Design of Journal Bearings Dimensions for Rotating Machines

Tariq M. Hammza; Ehab N. Abas; Nassear R. Hmoad

Engineering and Technology Journal, 2020, Volume 38, Issue 10A, Pages 1481-1488
DOI: 10.30684/etj.v38i10A.1093

The values of Many parameters which involve in the design of fluid film journal bearings mainly depend on the bearing applied load when using the conventional design method to design the journal bearings, in this study, as well as applied bearing load, the dynamic response and critical speed have been used to calculate the dimensions of journal bearings. In the field of rotating machine, especially a heavy-duty rotating machines, the critical speed and response are the main parameters that specify bearing dimensions. The bearing aspect ratio (bearing length to bore diameter) and bearing clearance have been determined based on rotor maximum critical speed and minimum response displacement. The analytical solution of rotor Eq. of motion was verified by numerical solution via using ANSYS Mechanical APDL 18.0 and by comparing the numerical solution with the preceding study. The final study results clearly showed that the bearing aspect ratio has little effect on the critical speed, but it has a high effect on the dynamic response also the bearing clearance has little effect on the critical speed and considerable effect on the dynamic response. The study showed that the more accurate values of bearing aspect ratio to make the response of rotor as low as possible are about 0.65 - 1 and bearing percent clearance is about 0.15 - 0.2 for different rotor dimensions.

Experimental Study of Vibration on Pipe Conveying Fluid at Different End Conditions for Different Fluid Temperatures

Kayser A. Ameen; Mustafa J. Al-Dulaimi; Ali A. Hatem

Engineering and Technology Journal, 2019, Volume 37, Issue 12A, Pages 512-515
DOI: 10.30684/etj.37.12A.3

Dynamic behavior of a copper pipe conveying fluid at different fluid temperatures is investigated experimentally. Three types of supports are used, which are simply support - simply support, fixed – fixed support and fixed – free support. The effect of the support's types on the frequency and the amplitude of vibration for the pipe conveying the fluid are studied for various flow temperature. These vibration characteristics were tested at temperatures 50, 65 and 80 ºC

Study of the Wind-Induced Dynamic Response for a Parabolic- Trough Solar Collector

Mauwafak Ali.Tawfik; Bahaa.Ibrahim.Kazem; Haider.Hussein.Hamad

Engineering and Technology Journal, 2012, Volume 30, Issue 20, Pages 3637-3652

In this paper, the dynamic response of parabolic-trough due to wind loading was
conducted in different flow field environment and configurations experimentally
and numerically. First, Experimental modal analysis (EMA) was performed to
evaluate the vibrational characteristics for prototype of parabolic trough that
manufactured for this purpose. Direct pressure sensors array were used to measure
the pressure values over the parabolic trough model surface due to wind load at
different operational attitudes. Then, the dynamic response (displacement) of the
parabolic-trough due to measured wind loads (pressure) was measured
experimentally and numerically. The numerical solution for dynamic response was
performed using the finite element approach. The response of the parabolic-trough
to wind loads was evaluated for different wind velocities and different angles of
attack. A comparison between these results was made to verify the effect of the
angles of attack and wind velocity on the dynamic response. The results showed
that the suggested approach gave good indication for evaluating the wind load
effect on the dynamic response of parabolic trough the solar collector.