Reference no: EM132296492

Computer Aided Engineering and Manufacturing - Advanced solid modelling and finite element analysis Assignment - 5 MW/61.5 m wind turbine blade analysis

Assignment overview: A 61.5 m (nominal length) blade design has been proposed for a 5 MW wind turbine. As a design engineer you must undertake an appropriate finite element analysis to determine the structural integrity of the blade during operation. The blade is defined via the coordinate system below:

Before commencing the assignment, it is strongly suggested that students familiarise themselves with appropriate wind turbine blade anatomy and terminology, including:

• Aerofoil chord length, twist angle, aerofoil thickness, leading edge, trailing edge, camber.
• Blade shell, spar, and shear web.
• Tip speed ratio.
• Blade root region, blade power production region, and blade tip.
• Blade flapwise (out-of-plane), lead-lag (in-plane), and torsional motions.

Further references can be found in the appendix (A5).

Assignment requirements:

Blade modelling:

1. Create a surface model of the blade geometry in Creo using the reference material in A1-A3. Aerofoil sections are available on blackboard in .pts format for use.

2. Import the blade surface model into ANSYS mechanical and undertake plate surface meshing of an appropriate quality for a finite element analysis. Ensure plate connections are made between all surfaces of the blade.

3. Apply the material properties specified in A4 to the blade shell (15 mm plate thickness), and the shear web sections (25 mm plate thickness).

4. Fix the model appropriately at the blade root to simulate a cantilevered beam condition.

Blade load cases:

1. Apply the flapwise and lead-lag aerodynamic loads detailed in A1 as a varying uniformly distributed load (hint: use node select and apply nodal force components using the tabular option in 'Direct FE').

2. Apply a rotational inertial load about the y-axis equivalent to 13 rpm at the blade root.

3. Undertake an eigenvalue buckling analysis to determine the first four buckling modes and load factors. Use combined aerodynamic and rotational loading.

4. Produce a Campbell diagram for the first six natural frequency modes for rpm = 0 to 20 rpm at increments of 2 rpm. Do not apply aerodynamic loading.

Project report:

Produce a succinct report detailing your analysis and investigation (10 pages maximum - excluding cover sheet and abstract). The document shall be formatted to an acceptable standard for an engineering report. Use appropriate figures and tables to concisely convey results. The report shall include:

1. A description of the blade finite element modelling process with all relevant assumptions detailed.

2. An assessment of mesh independence and histogram of element quality.

3. Details of the net model mass, centre of gravity, and moment of inertias.

4. The resulting force and moment reactions at the blade root due to the aerodynamic flapwise and lead-lag loads only.

5. The resulting axial (z-axis) reaction due to the rotational load only.

6. Maximum blade tip deflections in the flapwise and lead-lag directions due to combined aerodynamic loading and rotational loading. If the undeformed clearance between the rotor plane and tower is 6 m, will a blade/tower strike be avoided?

7. Maximum von Mises stress value and location due to combined aerodynamic and rotational loading.

8. A Campbell diagram of the first six fundamental modes at rotational velocities ranging from 0 to 20 rpm. Do not consider aerodynamic loading in this case. Natural frequency excitation, while unavoidable, is highly undesirable. Is this blade at risk of natural frequency excitation while operating at its design speed of 13 rpm?

9. First four buckling load factors and respective mode shapes (detail the location of any regions which may pose a risk of buckling). Consider both aerodynamic and rotational loading in this case. Are the respective load multipliers sensible?

10. Briefly detail any conclusions and recommendations.

Attachment:- CFD Assignment Files.rar