Turbine Characteristics With Respect to Form of Blade Passages

 

Impulse Turbine.—It may be defined as a system in which all steam expansion takes place in fixed nozzles and none occurs in passages among moving blades.

A Single-State or Simple-Impulse Turbine.— Here the steam expands from its initial to its final pressure in one nozzle (or one set of nozzles, all working at the same pressure), resulting in a steam jet of high velocity which enters the blade passages and, by exerting a force on them due to being deflected in direction, turns the rotor. Energy of all forms remaining in the steam after it leaves the single row of blading is lost.

The steam volume increases whenever the pressure decreases, but the resulting velocity changes depend on the type of turbine. As a matter of fact, these velocity changes are distinguishing characteristics of the differ­ent types.

A Velocity-Stage Impulse Turbine has one set of noz­zles, with several rows of blades following it. In passing from the nozzle exit through one set of blades, the velocity of the steam is lowered by virtue of the work done on the blades but is still high. It then passes through a row of fixed guide blades which change the direction of the steam until it flows approximately parallel to the original nozzle direction, discharging it into a second row of blading fixed to the same wheel. The second row again lowers the steam velocity by virtue of the work delivered to the wheel. A sec­ond set of guide blades and a third row of moving blades are sometimes used.

The steam enters through a steam strainer and governor valve into a steam chest supplying the various nozzles spaced around a portion of the periphery. Individual nozzles may be opened or closed by a hand-wheel on the stem of the nozzle-control valve. The turbine wheel is mounted on a shaft which passes through the casing to bearings out­side, carbon packing being used in the shaft glands of this turbine to maintain steam tightness. The governor is mounted on the right-hand end of the shaft and operates the balanced piston governor valve through a lever and link. On the left end of the shaft goes the coupling for attaching the driven machinery. (E. M.)

 

 

Task: find all the peculiarities of this style.

 

 

b) Newspaper style

 

Text 1

 

Dependent

 

STUDENTS who want a bigger say in the running of universities will be reinforced in their view by the latest effort of the vice-chancellor of Liverpool University and some other academics.

Today these allegedly wise and learned individuals issue, under the patronage of the Right Wing Institute of Economic Affairs a statement of the "urgency of establish­ing an independent university".

By "independent" they mean one which is dependent on finance from rich private individuals and Big Business, instead of from the Government..

It is a monstrous misuse of the English language to claim that such a university would be independent. It would depend entirely on the good will of the rich, and would find its finances cut off immediately if it displeased them.

Universities already have to rely too much on Big Business sources of finance, including from US and other firms engaged in war preparations.

Whatever criticisms there may be about the Government's part in their finance at any rate there is some possi­bility of democratic control over the public money allocated to the universities.

There would be none if it all came as a result of board-room decisions.

 

 

Text 2

 

No to NED

 

SCOTTISH miners know from their own experience what Tory planning means. In the Scottish coalfield Gov­ernment planning aims to close pits employing 5,000 men.

This is a plan for poverty and the Scottish area of the National Union of Mineworkers is resisting it. It ought to be able to count on the Trades Union Congress for help.

But the T.U.C. leaders by a majority have decided to join Mr. Selwyn Lloyd's National Economic Development Council. They are thus to take part in the work of an organisation set up by the Tories to carry out Tory eco­nomic policy.

The T.U.C. chiefs say they will be able to criticize the Government's proposals. They can do so more effectively if they refrain from wedding NED.

By joining NED, the T.U.C. weakens the fight against Tory pay-pause policies and the Tory Government. Mr. Gaitskell will have a convenient excuse to soft-pedal La­bour's attack.

He will be able to trot out arguments against embar­rassing "our T.U.C. friends who are engaged in compli­cated and delicate discussions" and so forth.

The T.U.C. should be told to keep out of NED and help to smash the pay-pause instead.

 

 

Task: find all the peculiarities of this style.

 

 

c) The style of official documents

 

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