OWEC - Breadboard

The experiment evolved with construction of a breadboard built to add real hardware to the analytical part of this project. Loss factors are very difficult to accurately assess and baseline operations of breadboards can shed much light on the problem. Also, integrated parts behavior and sizing are more easily understood and debugged. The .5"x4'x8' wooden board and frame is hinged on a base thereby providing underside access to fasteners. It accommodates a .5"x2'x4' aluminum sheet portion having appropriate mounting holes for affixing energy converting components. The sheet includes two large holes for alternate flywheel or armature locations. Support components of the energy converting assembly are affixed to the aluminum portion and a wave simulator servo system, for controlling driveshaft reciprocation length and frequency, is affixed to the plywood portion.

Due to the horizontal orientation of the breadboard and driveshaft, means for simulating effective buoyancy and weight forces were required. A wave simulator servo system of consideration would implement two springs, in series, acting on the driveshaft. One non-constant spring models a buoy under varying conditions of partial submergence and a constant spring replicates the weight of driveshaft and buoy. This method was rejected in order to use gravity force of simpler 3, 5, and 10 pound weights sling suspended from a 5' high scaffold, by block and tackle, and connected to a driveshaft end thereby enabling simulation of various driveshaft weights and gravity. A servo system of a 3:1 reduction block and tackle configuration is connected from the other driveshaft end to the post on a drive disk and motor. A .25hp, 120v synchronous stepper motor, with t of 720 oz-in @ 72 RPM, is vertically affixed to the breadboard by a steel plate. The motor axle is perpendicularly mounted with a 15" diameter steel disk having six threaded holes, each 1" apart in radial alignment from hub to rim, for carrying a post. Placement of the post in a certain hole, relative to others, provides specific radii that translate disk rotation to sinusoidal motion and particular driveshaft stroke lengths ranging from 1.5' to 5.5' maximum. Reciprocation frequency is calibrated as a function of simulated wave period and manually adjusted with motor controls that allow speeds from 0-41.5rpm

During testing with the wave simulator, which was designed to exert linear forces of 150 pounds and simulate buoy and shaft weights of 15 pounds, it was quickly discovered that the motor was sorely under powered. The 3:1 gear reduction ratio of the simulator, shafts, bearings, and generator wielded a large amount of force on the system. At the extreme settings, maximum driveshaft travel could not be sustained due to motor undersizing relative to simulator torque. In particular, the selected transmission was overscaled and exerted inordinate resistance on the drive train. The unloaded axle, downstream of the transmission and without the generator attached, resulted in rotation speeds of 20-70 rpm but could achieve barely 20 rpm when the generator was in line. In final runs, the transmission was eliminated to directly connect the flywheel to the generator. Reduced friction produced more favorable operation and the motor enabled tests of 16-32 inch height waves.

Compiled data from interrelated assembly operation studies provides input power point values for modifying a preexistent computer program already written for this overall design. Program development has capability to correlate equations of motion for ocean wave height, length, period, and celerity for plotting vertical velocity of the hydroface as a function of time. Additionally, the sums of fundamental, secondary, and tertiary wave heights, etc. are described. Further development has enabled characterization of effective buoyancy from different buoy shapes, effect of driveshaft inclined reciprocation axes relative to various directions of wave procession, transmission calculations, and subsequent electrical output.

The experiment evolved with construction of a breadboard built to add real hardware to the analytical part of this project. Loss factors are very difficult to accurately assess and baseline operations of breadboards can shed much light on the problem. Also, integrated parts behavior and sizing are more easily understood and debugged. The .5"x4'x8' wooden board and frame is hinged on a base thereby providing underside access to fasteners. It accommodates a .5"x2'x4' aluminum sheet portion having appropriate mounting holes for affixing energy converting components. The sheet includes two large holes for alternate flywheel or armature locations. Support components of the energy converting assembly are affixed to the aluminum portion and a wave simulator servo system, for controlling driveshaft reciprocation length and frequency, is affixed to the plywood portion. Due to the horizontal orientation of the breadboard and driveshaft, means for simulating effective buoyancy and weight forces were required. A wave simulator servo system of consideration would implement two springs, in series, acting on the driveshaft. One non-constant spring models a buoy under varying conditions of partial submergence and a constant spring replicates the weight of driveshaft and buoy. This method was rejected in order to use gravity force of simpler 3, 5, and 10 pound weights sling suspended from a 5' high scaffold, by block and tackle, and connected to a driveshaft end thereby enabling simulation of various driveshaft weights and gravity. A servo system of a 3:1 reduction block and tackle configuration is connected from the other driveshaft end to the post on a drive disk and motor. A .25hp, 120v synchronous stepper motor, with t of 720 oz-in @ 72 RPM, is vertically affixed to the breadboard by a steel plate. The motor axle is perpendicularly mounted with a 15" diameter steel disk having six threaded holes, each 1" apart in radial alignment from hub to rim, for carrying a post. Placement of the post in a certain hole, relative to others, provides specific radii that translate disk rotation to sinusoidal motion and particular driveshaft stroke lengths ranging from 1.5' to 5.5' maximum. Reciprocation frequency is calibrated as a function of simulated wave period and manually adjusted with motor controls that allow speeds from 0-41.5rpm During testing with the wave simulator, which was designed to exert linear forces of 150 pounds and simulate buoy and shaft weights of 15 pounds, it was quickly discovered that the motor was sorely under powered. The 3:1 gear reduction ratio of the simulator, shafts, bearings, and generator wielded a large amount of force on the system. At the extreme settings, maximum driveshaft travel could not be sustained due to motor undersizing relative to simulator torque. In particular, the selected transmission was overscaled and exerted inordinate resistance on the drive train. The unloaded axle, downstream of the transmission and without the generator attached, resulted in rotation speeds of 20-70 rpm but could achieve barely 20 rpm when the generator was in line. In final runs, the transmission was eliminated to directly connect the flywheel to the generator. Reduced friction produced more favorable operation and the motor enabled tests of 16-32 inch height waves. Compiled data from interrelated assembly operation studies provides input power point values for modifying a preexistent computer program already written for this overall design. Program development has capability to correlate equations of motion for ocean wave height, length, period, and celerity for plotting vertical velocity of the hydroface as a function of time. Additionally, the sums of fundamental, secondary, and tertiary wave heights, etc. are described. Further development has enabled characterization of effective buoyancy from different buoy shapes, effect of driveshaft inclined reciprocation axes relative to various directions of wave procession, transmission calculations, and subsequent electrical output.
\| About OWECO \| Our Mission \| Inception \| Tank Test \| Breadboard \| Drawing \| \| OWEB Map \| Proposal \| Contact Us \| Discussion Forum \| - Ocean Wave Energy Company -