Impeller Blades

I assume we are talking about a centrifugal compressor impeller. You really need to be more specific, this is a very complex subject.

Very simplistically back-swept blading has

• reduced work input for set tip speed and reduced Mach number at the impeller for specific work input.
• improved stability because of a nice pressure rise characteristic.
• peak efficiency is away from surge whereas for a radial impeller it is too close to surge.
• Better blade loading with less losses.

Sure I missed something or got something not quite right but thanks anyway to R.L. Elder - CIT

I too have some questions to ask about this.

• Doesn't the arched vane not only increase the the pressure but also the vacuum at the inlet?
• Doesn't the inner end of the vane is placed on the rotating table in an angle so that it seems to leads the outer end of the vane? (Meaning that the back or concave side of the vane has a cavity that at forward motion creates a vacuum?)

Hello Isti80:

Just to say.....................I could not AGREE more on your Signature, and 'Political Correctness!

Maybe if there was a little less Political Correctness'', there would be less kids running around knifing people etc.

When we did anything wrong, any of my neighbours were free to say what they thought and just shout at us if they had to, but, it worked, and got things done! And stopped potentially dangerous things happening. Whay they would call 'Anti-Social' things I guess you could say?

Thats my view anyway.

Take care.................

Thanks babybear.

I actually meant it more for adults than kids. Adults who already grew up like today's kids (Spoiled brats?) and obviously they can hardly behave any better than their children, if at all.

(I too used to be reprimanded all the time: on the way to school, at school, on the way home from school, at home and so on.)

Hello Isti80:

Think I know what you mean. I get kinda fed up when friends and just general parents these day, do not have any idea how to raise kids. Always blaming the child's poor behaviour on television, or, there is no where to do anything, no where to do this and that, you know? I was pretty poor when I was young and, our playground was the local woods. Making bow and arrows, camps swings etc. I never had any toys other than a ball and tennis racket.

Seems odd, that in real terms todays kids have so much but not only expect more but, are so blo-dy rude. I am not saying all kids but the ones who have computers, game-boys, their own TV and two or three Mobil phones. You know the thing?

My godson who I have disowned now for his rudeness, at 8 years old, when his Dad was at work his Mum just refused to say anything when he was f-ing and blinding at me because I might have said what he was doing was wrong? The worst thing was when his Mum would talk about him when he was watching and listening. So she may say, "I can't stop him from going out at midnight and I can't tell him what to do. His Dad will tell him when he gets home. Of course by then after his Dads night shift all was forgotten. He is 16 now and I have seen him twice since he was 8. But, when a boy spits in my face and scratches my face as well, and his Mother stands there and laughs..........Well. I think you get my drift.

Take care...........

Hi babybear,

Good on ya, dumping that spoiled brat.

Wonder what the mother's reaction was? I think she probably couldn't care less anyway.

I came up with my current signature after some discussions I used to have and I could notice how sometimes people (males) become occasionally reluctant to say what's on their mind.

Yet, the very essence of democracy is to be able to voice yourself but, due to this damn expression 'political correctness' is under mining the freedom of speech.

Maybe this 'political correctness' is a remanence of the senior Bush government's commitment, when at the end of the cold war they said, we should utilise the best of both systems, as neither were perfect.

With this expression, political correctness, you can shut and trivialise good people and things in order to give way to fools and crooks to praise and profile themselves.

This can include a lot of people in any society, from top politicians down to the last s...g, which make up the majority again in any society.

Of course some societies (the more politically correct ones) practise it with more care so their citizens do not notice it, least of all during an election campaign. While in the other camp there's no worries because oppression's the way...I hope you understand what I really mean!!!

Hello Isti80:

no worries, I fully understand your point!

And, the only reason she was not pleased I was not around her and her son any more, was because I was their 'Taxi'. The husband worked permanent night-shift and after 18:00 I was their only means of transport! He would not dare to speak to me the way he did in front of his Mum, .......IF his Father was there. He would get a right clip round the ear for sure! You could tell his attitude was changing as if you had flipped a switch. One minute it would be all nice and 'smarmy'. Then, when his Dad was out of the way the 'true' person came through. IE. The horrible one. And the way his Mum was around him and the way he was able to talk to her and push her around, was all her own doing! She would even shout at her husband if he told his son (my godson) off! He is still a bar-ta-d. But he is so thin he always loses in fights. He is the apple of his Mums eye. And he is going to grow up very quickly indeed when he leaves school!.

Thanks for getting back to me.

Take care..........

Hello babumechanical:

I have always thought the backwards pointing/slanting blades of an Impeller, were designed to allow the air or water to flow off the blade more efficiently, and not act as a 'brake'?

Just my idea. May not be right, but as a car has an up-turned rear to break the airflow and make the air-flow coefficient better, so the blades facing backs do the same thing. Not very well explained, but I have always thought that. I am open to any other 'real knowledge' though!

They are not backward. They are supposed to be that way, it is your pre-conceived notion of which way they should curve that is backward

Hello Guest,

whatever........