planetmeister_2000 wrote: > > Fellow group members: > > I'm constructing a crossflow turbine for a high-flow > low-head canal. The head is about 5 feet, and the flow is > 3-6 cubic feet per second. > > I have designed a runner with a diameter of 20 inches and a > length of 60 inches. There are 25 blades with a central angle of 42 > degrees and a radius of 7.38 inches (following Aziz' design) > > I want to construct a wide nozzle to capture all the flow - > > could you help with some theoretical proportions for the nozzle? I'd > The literature isn't very clear on this... I would > greatly appreciate it!! > > Thanks! > > Mike Bishop > [EMAIL PROTECTED]
Mike, For the crossflows we make, the width of the nozzle at maximum opening is 9.5% of the runner diameter. So for a 20 inch runner, the value is 1.9 inches. However, our design is a little different from yours - we use 18 blades and for a 20 inch runner we would have a blade radius of 6.52 inches. Other members of the group may be familiar with the particular design you have chosen and be able to improve on the 9.5% value I have given - but even so, I would expect it to be much the same. With a 1.9 inch nozzle width, using the values you have given, the turbine will handle a maximum flow of 13.1 cubic feet per second. So, the turbine will always be operating at part flow. Now, whilst the part flow efficiency of a crossflow is good, the turbine is much bigger than you need. If you are sure that the maximum flow you want to cater for is 6 cubic feet per second then I suggest you reduce the width and/or diameter to limit the maximum flow to 6 - 9 cubic feet per second. I have crossflow design software, as an Excel spreadsheet, which I am happy to provide, however it uses the metric system of units. Contact me directly if you would like a copy. Regards, Max Enfield Planetary Power ------------------------ Yahoo! Groups Sponsor --------------------~--> In low income neighborhoods, 84% do not own computers. At Network for Good, help bridge the Digital Divide! http://us.click.yahoo.com/EA3HyD/3MnJAA/79vVAA/FGYolB/TM --------------------------------------------------------------------~-> Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
