Humpback-Inspired Savonius Turbine Testing

ISEF Category: Energy: Sustainable Materials and Design

Subcategory: Wind and Water Movement Power Generation  ·  Difficulty: Intermediate  ·  Setup: School Lab  ·  Time: 1 to 2 Months

The Hook

A whale’s flipper can help make a wind turbine better. That sounds odd, but tubercles, the bumps along a humpback whale’s flippers, can change how air moves over a blade. You can test whether the same idea improves a small Savonius turbine. The result is a clean engineering project with real numbers, not just a cool-looking model.

What Is It?

A Savonius turbine is a vertical-axis wind turbine. Picture two curved scoops that catch the wind and spin around a center shaft. It is simple, sturdy, and easy to print in parts. The power coefficient tells you how well the turbine turns wind power into useful mechanical power. Higher is better, up to a point.

Tubercle edges are small bumps or waves along the blade edge. Humpback whales use them to change how water flows over their flippers. In air, those bumps can delay flow separation, which means the air stays attached to the surface longer. That can change torque, start-up behavior, and performance at different wind speeds. Your job is to test whether a tubercle pattern helps a small Savonius turbine, and whether the effect changes as wind speed rises.

Why This Is a Good Topic

This is a strong science fair topic because you can change one design feature, measure one clear output, and compare several versions under the same wind conditions. It connects to clean energy, turbine design, and biomimicry, which means copying ideas from nature to solve engineering problems. You can learn how to plan controls, graph performance curves, and judge whether a design change really helps or just looks fancy.

Research Questions

• How does adding tubercle edges to a Savonius turbine change its power coefficient at different wind speeds?
• What is the effect of tubercle size on the turbine’s starting torque in a box-fan wind tunnel?
• Does a tubercle pattern improve efficiency more at low wind speed than at high wind speed?
• To what extent does the number of tubercle waves around the blade edge affect rotational speed?
• Which blade design, smooth or tubercled, produces the most stable output across repeated trials?
• How does the tubercle pattern change the turbine’s response when the wind angle shifts slightly?

Basic Materials

• 3D printer or access to one, with suitable filament.
• Savonius turbine STL files or CAD software to design your own.
• Box fan with adjustable speed settings.
• Digital tachometer or optical RPM sensor.
• Small multimeter or data logger for voltage and current.
• Resistor load set or adjustable electronic load.
• Anemometer for measuring wind speed.
• Tripod or fixed stand to hold the turbine in the same spot each trial.
• Ruler or calipers for measuring blade features.
• Notebook or spreadsheet for recording results.

Advanced Materials

• Access to CAD software for iterating blade geometry.
• 3D printer with fine-layer settings for comparing edge shapes.
• Wind tunnel or ducted fan setup with controlled airflow.
• Torque sensor or inline dynamometer.
• Microcontroller-based data acquisition system.
• High-precision anemometer.
• Laser tachometer or encoder for shaft speed.
• Variable resistor bank or programmable load.
• Force balance for drag or lift-related measurements.
• Flow visualization supplies such as smoke, yarn tufts, or dye tracing, if the lab allows it.

Software & Tools

• Excel or Google Sheets: Organizes trial data, calculates power coefficient, and makes comparison graphs.
• ImageJ: Measures blade geometry from photos and checks whether printed tubercles match your design.
• Fusion 360: Helps you design and compare turbine blade variants before printing.
• Python: Helps you fit curves, compare groups, and test whether differences are real.
• Logger Pro: Records sensor data and supports clean time-based analysis if your school has it.

Experiment Steps

1. Define the exact blade feature you will change, such as tubercle size, spacing, or edge shape.
2. Choose one baseline Savonius design and keep every other dimension the same across versions.
3. Plan how you will measure wind speed, rotor speed, and electrical output at the same test points.
4. Build a comparison set that includes at least one smooth control and one or more tubercled variants.
5. Decide how you will convert raw measurements into power coefficient so you can compare designs fairly.
6. Set up repeated trials and a data table that lets you check consistency, not just peak performance.

Common Pitfalls

• Changing blade shape and rotor size at the same time, which makes you unable to tell which feature caused the result.
• Measuring output without a steady wind-speed reading, which turns your power curve into noise.
• Using a box fan without fixing turbine position, which changes the airflow angle and distorts comparisons.
• Comparing a single lucky run to another design’s average, which creates false winners.
• Ignoring print quality differences, which means rough surfaces or warped blades can hide the real tubercle effect.

What Makes This Competitive

A stronger project goes beyond a simple before-and-after comparison. You can test several tubercle patterns, look at performance across a range of wind speeds, and report both average output and repeatability. Good controls matter here, along with clear error bars and a fair way to compare designs. A top entry also explains why a certain geometry works, not just which one won.

Project Variations

• Test whether tubercle edges help more on a two-blade Savonius turbine than on a three-blade version.
• Compare tubercle patterns on the leading edge versus the trailing edge of the blades.
• Analyze whether tubercle modifications improve electrical power output, rotor speed, or self-starting behavior most strongly.

Learn More

• NOAA National Weather Service education resources: Search for wind basics and turbine-related background on NOAA’s education pages.
• NREL wind energy basics: Find free explanations of wind turbine performance and rotor design on the National Renewable Energy Laboratory site.
• NASA Earth Observatory: Search for articles on wind, drag, and fluid flow concepts that help explain biomimicry.
• MIT OpenCourseWare fluid mechanics: Use free course notes and lectures to review flow separation, drag, and lift.
• PubMed: Search review articles on biomimetic blade design and humpback whale tubercle aerodynamics.