Hi Eilrem, Have you determined your turbine's efficiency yet? Also, how did you compute the ideal tip speed ratio? I have material that computes diameter, speed and power from flow and head, but nothing on blade pitch. I guess this is buried in the specific speed of the prop, but I don't have info on how to get from specific speed to blade pitch. Could you point me towards reference material that would be helpful? Thanks kindly, Martin
--- In [email protected], Eilrem Fernandez <[EMAIL PROTECTED]> wrote: > Hi, > > I've tried using a boat propeller on one of our axial turbines (15kW, 3m gross head) and it worked. What I did is: first I computed for the ideal blade profile based on flow rate, gross head, and RPM requirements. Then, I looked for a propeller that closely matched my computations. By buying an off-the-shelf component, I ensure that replacement parts for the turbine will be available without special fabrication, although you have to sacrifice a bit of efficiency due to the inappropriate shape of the blade tip. The difficult part is in looking for a propeller that closely matches what you need. > > The blade has only a limited range of tip-speed ratio wherein it will operate at high efficiency. Increasing the tip speed will increase the RPM and reduce the pitch for a given head and flow rate. Increase in head will increase the RPM and flow rate if the turbine size remains constant. > Flow rate is proportional to the axial turbine's cross-section and is related to the square-root of the gross head. > > Use of flat plates will reduce your efficiency but if the flow rate is more than sufficient, I think it is worth it for a bit of sacrifice in efficiency in excange for simplicity of design, fabrication and maintenance. > > Axial pumps are not so available in the Philippines but there is a wide variety of propeller sizes, shapes and configurations. ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/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/
