Dynamic Balance of hydraulic turbine runner
Dynamic Balance of hydraulic turbine runner
(OP)
Hello everybody:
As a normal practice in the manufacture of hydraulic turbine runners, the Technical Specifications indicate to perform in the final steps of the process, the static and dynamic balancing of the runner.
In one particular case, the manufacturer agrees to perform only the static balance but not the dynamic balancing. Regardless of the Specifications, under what circumstances the dynamic balancing can be ignored? Technically, how can the manufacturer support this position? Should be the owner of the equipment rigorous in demanding the realization of this dynamic balance?
Your comments are welcome. Thanks in advance.
As a normal practice in the manufacture of hydraulic turbine runners, the Technical Specifications indicate to perform in the final steps of the process, the static and dynamic balancing of the runner.
In one particular case, the manufacturer agrees to perform only the static balance but not the dynamic balancing. Regardless of the Specifications, under what circumstances the dynamic balancing can be ignored? Technically, how can the manufacturer support this position? Should be the owner of the equipment rigorous in demanding the realization of this dynamic balance?
Your comments are welcome. Thanks in advance.
El que no puede andar, se sienta.





RE: Dynamic Balance of hydraulic turbine runner
staical and dynamical balancing cure different illnesses, see sketch. At rot-speeds where centrifugal forces have to be considered, dynamical balancing is a must. Ask the bike people, if you want to go fast you take care of the wheels, those shouldn't start "hammering" @ 35 mph or so. But don't take this number to your case...
In general, it is not only balancing as such, but in some cases this should be done for 2 or even 3 planes of the object.
The effect of disbalance is centrifugal forces, additional dynamical loads on bearings, shafts etc. Then this can induce frequencies leading to excitation --> resonance. Further effects as per your particular case.
Given all factors their due consideration --> dynamical balancing might not be necessary. Commonly seen at low rot- speeds. A case decision for the agreed specialist / appointed expert.
Regards
R.
RE: Dynamic Balance of hydraulic turbine runner
RE: Dynamic Balance of hydraulic turbine runner
Thanks for your valuable opinions.
El que no puede andar, se sienta.
RE: Dynamic Balance of hydraulic turbine runner
RE: Dynamic Balance of hydraulic turbine runner
RE: Dynamic Balance of hydraulic turbine runner
These are Francis turbines, with 1.035 mm in diameter and rotating at 720 RPM. The nominal water flow is 7,5 m³/s per turbine and a net head of 120 m.
El que no puede andar, se sienta.
RE: Dynamic Balance of hydraulic turbine runner
RE: Dynamic Balance of hydraulic turbine runner
David
RE: Dynamic Balance of hydraulic turbine runner
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)