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Jeff,
To give the short answer, Mazda is turning the impeller in the correct direction (namely in the direction correlating to the increasing scroll volume, as depicted in your "Water Pump Pulley 03.jpg").
The long answer is that the impeller blades, oriented as they are, is a stable, wide operating band style impeller. To use an aircraft analogy, this pump has a positive static margin.
Something that's interesting about pumps such as this is that they can squeeze more efficiency out of the impeller by rotating the blade on the impeller. The downside to increasing the efficiency in this manner is that the operating range is reduced and, similar to reducing the static margin in an airplane, is that you pay for it in stability. If a pump of this design were "flying" at its neutral point, the blades would be oriented radially from the axis of rotation. Continuing with the airplane analogy, if the pump were "flying" with negative static margin, but also at its most potentially efficient, but also most likely to cavitate and go unstable, the blades would be mirror-imaged from the orientation they're in now, but still rotating in the same direction.
I'm sure what I've explained is clear as mud, yes?
Anyway, hope it helps.
Regards,
Cedric Gould
On 8/5/2011 5:13 AM, Jeff Whaley wrote:
Why do I get the feeling these impellors are being turned in the wrong
direction?
Image 1 is a scan of a test engine … from my cockpit the prop turns
clockwise and so does the e-shaft with an RD1-C - as referenced to this
scanned image.
Now look at these water pump impellors … if I wanted to move water I’d
cup my hand and scoop it, not use the back of my hand.
Has Mazda got this wrong? Or am I missing something?
It looks like I’ll have to change the water pump, as the flange may be
warped and the thread bosses are definitely burred.
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