M.D. Jenks’s scientific contributions

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Publications (3)


Photoelastic stress analysis on a Phoenix 7. 9-meter blade
  • Conference Paper

October 1991

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4 Reads

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1 Citation

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M.D. Jenks

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R.M. Osgood

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J.A. Johnson

Photoelastic tests were conducted on the Phoenix 7.9-meter blade to develop the basic methodology for locating critical strain areas on full-scale composite structures. Under relatively low elastic loading the strain fields over various regions on the blade planform were documented with 35mm photographs under different loading conditions at the Solar Energy Research Institute (SERI) Structural Test Facility (STF). Strain concentrations were easily located and quantified. Principal strain magnitudes and directions were determined at the highest strain areas using separator gages. Results were compared to measured operating loads. This experiment demonstrated the value of experimental stress analysis using the photoelastic technique for the evaluation of composite blade designs. 9 refs., 6 figs., 3 tabs.


Aerodynamic pressure measurements on a rotating wind turbine blade

May 1990

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22 Reads

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6 Citations

A microprocessor-controlled measurement system has been designed and built to make accurate measurements of low pressures on a rotating wind turbine blade. This Pressure System Controller (PSC) is capable of simultaneously operating four pressure scanners (128 channels total) while rotating on a wind turbine blade. Calibrations and purge sequences are performed automatically on all 128 channels while the turbine is rotating. Data are fed to a Pulse Code Modulation (PCM) data-acquisition system and recorded on magnetic tape for later processing. Accurate measurements have been made down to pressures of 11 microbars (0.00018 psi) for low Reynolds Number tests. These rotating-blade pressure measurements are used to compare with wind tunnel data to see how blade rotation alters airfoil performance. A description of the test setup and instrumentation design is given along with examples results. Recommendations for future work and changes in the design approach are also discussed. 7 refs., 13 figs.


A comparison of two- and three-dimensional S809 airfoil properties for rough and smooth HAWT (horizontal-axis wind turbine) rotor operation

February 1990

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33 Reads

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12 Citations

At the Solar Energy Research Institute (SERI), we carried out tests to measure the effects of leading-edge roughness on an S809 airfoil using a 10-m, three-bladed, horizontal-axis wind turbine (HAWT). The rotor employed a constant-chord (.457 m) blade geometry with zero twist. Blade structural loads were measured with strain gages mounted at 9 spanwise locations. Airfoil pressure measurements were taken at the 80% spanwise station using 32 pressure taps distributed around the airfoil surface. Detailed inflow measurements were taken using nine R.M. Young Model 8002 propvane anemometers on a vertical plane array (VPA) located 10 m upwind of the test turbine in the prevailing wind direction. The major objective of this test was to determine the sensitivity of the S809 airfoil to roughness on a rotating wind turbine blade. We examined this effect by comparing several parameters. We compared power curves to show the sensitivity of whole rotor performance to roughness. We used pressure measurements to generate pressure distributions at the 80% span which operates at a Reynolds number (Re) of 800,000. We then integrated these distributions to determine the effect of roughness on the section's lift and pressure-drag coefficients. We also used the shapes of these distributions to understand how roughness affects the aerodynamic forces on the airfoil. We also compared rough and smooth wind tunnel data to the rotating blade data to study the effects of blade rotation on the aerodynamic behavior of the airfoil below, near, and beyond stall. 13 refs., 11 figs.

Citations (3)


... the typical size of wind turbine blades has grown past the current testing capabilities at NREL. For smaller wind turbine blades, the bending moment in the flap direction is the predominate fatigue factor [27,28]. As blades have increased in size, the lead-lag bending moment, influenced primarily by blade weight, became a significant factor in damage calculations. ...

Reference:

New Method for Dual-Axis Fatigue Testing of Large Wind Turbine Blades Using Resonance Excitation and Spectral Loading
Photoelastic stress analysis on a Phoenix 7. 9-meter blade
  • Citing Conference Paper
  • October 1991

... For the visualization of regions with separated flow so-called stall flags are used [8], which have to be mounted on the rotor blade surface. In addition, surface pressure measurements with pressure taps and microphones [4,2,39] or hot film measurements [38] are possible, though these methods are invasive to the rotor blade surface. The preparation of the rotor blade is time consuming and the precise positioning of the equipment is a costly process, as a turbine stop and the ascent by rope access technicians or the use of a work platform is necessary. ...

Aerodynamic pressure measurements on a rotating wind turbine blade
  • Citing Conference Paper
  • May 1990