Hi dear all
I'm interest in Wind Turbines and I found tow types Horizontal Axis & Vertical Axis, I wonder which one is more efficient? why? thank you
I´ve been reading about wind turbines and found out about your question, so I´m sending you an interesting files comparing boths types of turbine..you might like it .
Best regards!
Industrial wind turbines fall into two general classes depending on how they spin: horizontal axis and vertical axis. Vertical axis machines, which spin about an axis perpendicular to the ground, have advantages in serviceability since all of the control equipment and generator are at ground level. The main drawback to this configuration, however, is that the blades cannot be easily elevated high into the air where the best winds blow. Vertical axis turbine types would hardly be able to beat the efficiency of a propeller-type turbine. As a result, horizontal axis machines "HAWT"— which spin about an axis parallel to the ground rather than perpendicular to it — have come to dominate today’s markets. All grid-connected commercial wind turbines today are HAWT. Megawatt-sized HAWT's will be ideal for offshore applications, and for areas where space for siting is scarce, so that a megawatt machine will exploit the local wind resources better.
I agree with Malawi. VAWT are sometimes better in low wind speed areas. They can work with winds blowing from each direction. But in HAWT there is a yaw motor which turns the nacelle towards the wind direction. To summarize, in commercial scales, HAWTs are better.
I have a VAWT design that could potentially be as efficient as a HAWT.
Normally VAWT are non directional which makes them simpler in design and control. this however mean they are less efficient.
I created a VAWT that would tack into the wind like a sailing boat using aerofoils though - it never really got of the drawing board although I did do a number of simulations.
Wind is parallel to ground surface. If the turbine has an horizontal axis all its blades are in same position with respect to wind. Of course if the rotor has big diameters the ratio between axial velocity and tangential will chnage and impose a special profile and even an angular dependen control.
If the axis is vertical there are several aspects reducing the efficiency. First of all is the fact that the tangential velocity of the rotor which is in the horizontal plane (the same as the wind wectors) makes with the wind vector an angle from zeo to 360°. At zero it has same direction at 180° it is exactly the opposite and at 90 and 270° it is normal to it. Part can be corrected but not all!
This is quite difficult to explain but if you continually change the pitch of the areofoil with respect to wind direction you achieve a positive rotational vector whatever the rotor position with the exception of 90 and 270 degrees where the pitch is at zero (as it crosses over).
Imaging an aeroplane wing tipped up on its end which is powered and controlled such that it always provides a positive rotational vector. The wing is powered with a geared motor but it always goes with the wind so to speak so the motor power is not that great. The efficiency of this design will never probably be as good as a HAWT however the advantages are that the generator is low to the ground and the pitch can be set optimally in low wind and less optimally in high wind so it will work in gale conditions. I thought this design would be good for tidal as all the electrical moving parts could be above the water line. I never proceeded with the design as I never was able to convince the patent office it was novel there are a lot of patents on wind turbines.
Do not undersetimate the reduction in relaibility of a too complex system which could have MTBF so small that the maintenance cost will be prohibitive. As always the problem isto find the RIGHT compromise.
Dear All
Thank you for your helpful comments I'll print them and study carefully and answer with my thoughts.
regards to all
With regard to your original question. What is the most efficient.
A good analogy would be antennas. A VAWT the barrel or egg whisk type - you know the ones with the long names can be regarded as dipoles ie: just a length of conductor - almost omnidirection - they radiate everywhere.
Whereas a HAWT could be regarded as a parabolic dish which has a massive gain but only in one direction.
So the VAWT rotate whatever the wind direction but with less power compared to HAWT which you point into the wind.
Horizontal axis wind turbine is more efficient than vertical axis..bcoz vertical axis only used for small power applications..
Wind is parallel to ground surface. If the turbine has an horizontal axis all its blades are in same position with respect to wind. Of course if the rotor has big diameters the ratio between axial velocity and tangential will change and impose a special profile and even an angular dependent control.
It doesn't matter which is more efficient. Doesn't matter! What matters is which gives you the most energy at the best time for the least money. The answer will be different for each location and turbine size. On your house, you'd probably go for the VAWT, because it's less complicated and works on lower windspeed.
As-Salamu Alaykum,
for the normal causes, generating power for the grid, the horizontal axis is better. Although for stand-alone solutions the vertical axis could be better for small power (up to 50kW).
Greetings from Germany
Vertical Axis Wind Turbines (VAWT) are of two types: Savonious and Darrious. There are five configurations in Horizontal axis wind turbines (HAWT). For low speed applications, VAWT are recommended and these can rotate for any direction of wind. However HAWT are more efficient because of its high tower height. for each 10m increase in height, 20% increment in wind speed and 34% increment in power. Large scale HAWT with pitch and yaw control are more efficient and reliable.
Dear friends
I'm thankful very much for your support answers.
Now I wonder if any one can help me to find a supplier to supply me with a VAWT home type about 3 or 5 Kw, in turky or jordan and the price please?
There are quite a number of China company for low speed WT. You can search from the Small WT. In thailand, we have some University design and construct WT for low speed (1-25 kW). Please search in Dr.Wichai at Rajchamangkara Technonolgy University at Pathumthani province (near Bangkok). that's all.
It completely depends on the conditions.If u need to have high torque and wind speed is usually slow (less than 8m/s) then VAWT will be better but then you will have to sacrifice with the speed but if the you got to need high speed and wind speed is fairly good HAWT is used .HWAT is basically used to electricity generation.
Dear Mr Mohannad,
Each type has its applications. It depends on the wind speed and place to be fixed on. Any way the horizontal axis with propeller blades is the most common one, since its efficiency is about 60%.
Regards
Crazy idea that I will throw out there. A VAWT turbine could be used as the top for a minaret or other tower to provide not only energy but a distinctive structural element. Rather than a spherical structure, an onionlike structure could be used and made of anodized aluminum to provide color and beauty. Am I totally off the deep end here?
The VAWT offer the advantage of locating the generator (the most heavy part) flat on the ground, but the fatigue effects on the blades are much higher and they break easily. The other problem is that near the ground the wind speed is lower and more turbulent. For those reasons you will find very few VAWT in commercial wind farms around the world.
For anyone interested in exploring the commercial potential of the latest wind turbine research, you may want to join us at (or present your research at) the upcoming Future Energy conference in New York and Boston. If you're working on revolutionary research in this area, we'd love to hear from you.
http://futureenergy.eventbrite.com/
http://ultralightstartups.com/future-energy-startup-application-form/
Graham.
Can you suggest me a project related to this topic for my b.tech major project
Q: For BLDC motor for wind turbine of 8V DC(with 15 degree) 50-60 wattt
Which wind turnbine design is better verticle or horihontal?
What could be size i.e length of the blade?
What could be weigth of the blade?
What is the optimun range of the speed?
mail me indipendent or all anawer:
Mr Sunil Payak follow below mentioned list: I guide what to do next to publish a paper on the same...
Dr Dharmasa-00968-95231621
For BLDC motor for wind turbine of 8V DC(with 15 degree) 50-60 wattt
Which wind turnbine design is better verticle or horihontal?
What could be size i.e length of the blade?
What could be weigth of the blade?
What is the optimun range of the speed?
mail me indipendent or all anawer:
Catch the power of the gusts with the VA. Some one needs to computer model the fluid motion of the wind with different blade shapes.
I´ve been reading about wind turbines and found out about your question, so I´m sending you an interesting files comparing boths types of turbine..you might like it .
Best regards!
My understanding is that a significantly greater aerodynamic efficiency can be obtained with a HAWT. Two reasons for this are that (1) a HAWT can be designed so that its blades operate at the optimal angle of attack, and (2) a VAWT will always suffer from interference effects between blades that will cause turbulence and reduce efficiency. That said, what is usually most important for wind turbines is not efficiency but overall cost of energy (COE). The greater efficiency of HAWT's helps give them a lower COE than VAWTs in many cases, which is why HAWTs are the standard choice for large-scale wind energy. However, there are probably applications in which VAWTs would have a lower COE and would therefore be more suitable.
I am fascinated by the innovation of generator designs which might incorporate a different mounting axis. Almost all airflow is horizontal; however axis mounting, for force capture, can include vertically engineered construction. The design I am looking at would effectively reduce the 'eyesore' complaint of wind power detractors. By modifying the ubiquitous windmill design of current wind power intallations, I believe wind force could be captured as it skims along earth or marine surface. A horizontal axis mounted blade wheel (similar in design to a typical blower motor) would enable a lower profiled installation.
You can found some graphics following image. The power coefficient Cp as a function of the tip speed ratio for different wind machines designs. Note that the efficiency curves of the Savonius and the American multiblade designs were inadvertently switched (Eldridge, F. R., 1980) in some previous publications, discouraging the study of the Savonius design.
The theoretical maximum efficiency of a wind turbine is given by the Betz Limit, and is around 59 percent.Practically, wind turbines operate below the Betz Limit.
http://www.intechopen.com/source/html/16242/media/image67.jpeg
Horizontal axis for sites with a small variation of wind velocity and vertical axis for large variation of wind velocity and direction, turbulence.
Collarabarative work or good quality of reviewing leads good project/paper, which is useful for the society.
Problems of reseach coordination:
Non-payment of nominal charge for revieweing research papers for the below mentioned conference. http://www.iccsit.org/
I have been cheated by above organization by not paying of nominal charge for revieweing research 16 research papers. I have all communicated information/documents with Reviwer Code: EN300117-ICCSIT ; http://www.iccsit.org/, aper code ,email:[email protected].
Can I say please don't review papers of such conference, which is not having basic ethics of engineering.
From: Dr.Dharmasa,
Caledonian University College
Oman -968-95231621
Hello,
HAWT are typically more efficient than VAWT (power coefficient of HAT are arround 0.4-0.5 and 0.3 for VAWT. It is because in an VA system when the blade are in the downstream they are not efficient!!
In connection with HAWT and VAWT. Now we have to design a blade in such way that it must take/convert enitre/almost all wind energy (flowing top-to bottom or from left to right)into power.
It is IMPOSSIBLE since if you take all energy the air does not move any more. Have you heard about theory of Betz which defines the maximal portion of wind energy which can be harvested?
As for the VAWT it is really effective on only 1/3 of path if blades are oriented as function of angle to wind.
It is a solution to obtain a better result but I let you find it.
Nick Hamburger, it nice to see your knowledge. Regarding Rankine- Betz euqations
Blades are take energy.
Please keep Vertical-Horizontalmotion of baldes hab as reference.
Dear Dr.Dharmasa,
Here are two sources of information for you, the fist is a book quite new (2011) and covers the whole field, the second is only as written an explanation how the Betz equation can be derived.
1-Wind Turbines Theory - The Betz Equation and Optimal Rotor Tip ...
www.intechopen.com (open acces)
2-The derivation of the Betz limit for a wind turbine
www.wind-power-program.com/betz.htm
I knew the equation was written first y Betz in 1919 but I never saw ths equation connected to Rankine's name. Could you please indicate a source where I can see why this connection ?
I would appreciate.
Thanks
PS Please explain better what you wrote in your last 2 sentences, I do not get the point and I would prefer to undestand what you wanted to say.
Dear Mr DH,
I am still waiting an explanation of your text. Is it so difficult for you to give it an understandable form ?
Nick wait,
I am happy to hear yes it is difficulty make understand.
I think vertical are more efficient in terms of real estate usage (less land required) and the source of wind itself vary vertically as well (which should be utilized as well)
Hi to all,
some years ago (60's - 70's) a lot of prototypes were built to test the efficiency of the most common HAWT and VAWT. These studies gave as results the graphs that are presented in the document that L. Andrada has attached.
Despite of its simpler design the VAWT designs tested were less efficient, mainly because of its blades could face the incoming wind flow properly when they were downstream, as J-F. Charpentier said. The reason is that the downstream flow is disturbed by the upstream blade.
HAWT instead, they do face better the incoming wind flow.
After those experimentation years HAWTs started to commercialize.
Nevertheless, as A. Szewczyk says, I think that VAWTs could present a higher energy / land-area than HAWTs.
Hope it helps!
Sorry, mistake!
[...]
Despite of its simpler design the VAWT designs tested were less efficient, mainly because of its blades could NOT face the incoming wind flow properly when they were downstream, as J-F. Charpentier said
[...]
It is not only about the Betz number, but also the zone 1, 2 and 3 windspeeds. The cut-in and cut-out speed. When the turbine begins to spin and when the turbine has are significant aerodynamical torque. E.g. if a turbine is rated at 10kW at the end of zone 2 and the beginning of zone 3, and I connect it with a load of 2kWh at a wind speed beyond the cut-in (e.g. 12m/sec) and it cannot spin around anymore because of a lack of aerodynamic torque. Than what is the use of the system?
VAWT have the properties of starting to spin around at low speeds (some manufacturers claim 2-5m/sec). But the aerodynamical torque is really far below standard. Meanwhile HAWT have between 5m/sec - 12m/sec) already a significant torque to spin a generator with a significant load.
Nevertheless HAWT's are quite huge and need height and space.
My personal preferences are HAWT's beacause of their controlability and high torques at low wind speeds (10m/sec- 20m/sec).
Dear Mohannad Al-Mahdawi,
more description about the axes of wind turbine is mention in the following paper.
Rajeev Kumar, “Electrical and wind energy co-ordination system for vehicles” International Conference on Methods and Models in Science and Technology (ICM2ST-10), published in American Institute of Physics, New York, USA, AIP Conf. Proc. 1324, pp.140-144, Dec. 2010
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Energy
- Energy-Generating Resources
- Renewable Energy