Causes of unbalance - aircraft design, Other Engineering

Assignment Help:

Causes of unbalance

Unbalance may be caused by a variety of factors occurring singly or in combination with others. These factors include:-

a) Eccentricity

Eccentricity exists when the geometric centreline of a part or assembly does not coincide with its axis of rotation. This may be as a result of locating features (eg. spigot location, bolt holes, splines, serration's, couplings), being eccentric to the bearing location.

1544_cause of unblance.png

b) Variation in Wall Thickness

1705_cause of unblance1.png

Variation in wall thickness may be as a result of eccentricity between an inner and outer diameter of a cylindrical type feature, or it may be as a result of a difference in thickness between a radial section of a disk type feature and the section diametrically opposite.

c) Blade Distribution

Unbalance can be caused by an unequal or unsymmetrical arrangement of a set of blades, either by reference to their mass moments or their dead weights depending on the size of the blades. This can be as a result of faulty weighting, inaccurate or illegible recording or assembly errors.

d) Unsymmetrical Features

1508_cause of unblance2.png

These may be due to manufacturing processes, such as blow holes in castings or design features such as offset holes, locating dogs, slots, keyways, etc.

e) Distortion

This can be caused by stress relieving, eg. after welding, or by unequal thermal growth during running.

f) Fits and Clearances

Clearance between mating parts allows relative movement of the parts and a consequent shift of the axis of rotation during running (or even during balancing). Joints incompletely assembled, eg. chamfers fouling radii, abutment faces not pulled together, may cause a ‘bent' rotor or an unsuitable joint, which may cause a shift during running. It is important to prevent separate locating, or fixing, features from influencing each other eg. bolt holes, spigot locations, serration's, etc. must be geometrically controlled to prevent ‘fighting' between more than one feature. See also the section on tooling, adapters, drives, dummy rotors, etc.

g) Swash

362_cause of unblance3.png

Swash is caused by out of squareness of abutment faces relative to the bearing diameter, abutment faces not being parallel across the component, eg. spacers, adjusting washers, disks, etc. It is important that the bolted joints are tightened in sequence and in increments according to the torquing instructions.

h) Miscellaneous

Foreign bodies inside assemblies, oil accumulation, carbon deposits, usually found when check balancing after running.

 


Related Discussions:- Causes of unbalance - aircraft design

Embedded system, I have an assignment of engine control unit (hardware desi...

I have an assignment of engine control unit (hardware design and programming) if you have an expert.....

Determine the data rates for different modulation, Question: (a) OFDM s...

Question: (a) OFDM signals have a higher PAPR that signal carrier signals do. Describe (i) Why this is so and what is the impact on radio transmission systems? (ii) How

Finance derivative, What are the no-arbitrage lower bound, and the no-arbit...

What are the no-arbitrage lower bound, and the no-arbitrage upper bound, of the vertical spread c(k1)-c(k2)?

Trigonometry( bearings and rectilinear figures), a pilot entering a bay on ...

a pilot entering a bay on course 60.3 degrees at speed 12 miles per hour sees a light bearing 37.3 true and 20 minutes later he sees it bearing 20.0 degrees true. if he keeps the

What is basic function of subroutine, Question: a) Write the detailed ...

Question: a) Write the detailed operation/description of the following mnemonics: (i) MOVX @DPTR, A (ii) MOVC A, @A + PC (iii) PUSH add b) What is a subroutine and

Financial management, I have a homework assignment with 12 present value an...

I have a homework assignment with 12 present value and future value related investment problems. Can you guys help with me these types of problems please?

Sources of engine noise - aircraft design, sources of engine noise To u...

sources of engine noise To understand the problem of engine noise suppression, it is necessary to have a working knowledge of the noise sources and their relative importance.

Ubiquitous networks, Ubiquitous network applications are generally designed...

Ubiquitous network applications are generally designed for a whole network. This notion should be reflected in the way a network is programmed. We believe that providing abstractio

Oil pumps - aircraft engine, OIL PUMPS The oil pumps fitted in a recirc...

OIL PUMPS The oil pumps fitted in a recirculatory system are normally gear-type or Gerotor type pumps. The pumps are usually mounted in a pack containing one pressure pump and

Co-ordination number, Q.  Define co-ordination number. Ans.CO-ORDINAT...

Q.  Define co-ordination number. Ans.CO-ORDINATION NUMBER: The number of atoms which are directly surrounding a given atom is known as coordination number. Number of atoms w

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd