Session: IMECE Undergraduate Research and Design Exposition

Paper Number: 113536

113536 - Fluid Friction Dynamometer Senior Design 

The Northern Michigan University SAE Baja racing team needs a device to test their engines. The team has had issues with engines losing noticeable performance after particularly intense races but lacked a way of accurately quantifying the severity of the performance loss. This also meant that when repairs and maintenance were performed there was no way of verifying the effectiveness of the repair. Such a device would aid in troubleshooting any powertrain losses and wear as well. As part of a year-long, senior design project, a cost-effective, user-friendly, device was developed to allow the team to better assess when to do performance sustaining maintenance throughout the lifetime of their variously sized engines.  A fluid friction dynamometer was designed to assess the engine horsepower, torque, and speed on a benchtop outside of the buggy. The buggy’s engine drives a fluid pump via a belt and pulley system that includes a tachometer to measure the RPM. The pump is powered to push hydraulic fluid through a reservoir in a closed fluid loop.  Two pressure transducers separated by a flow throttling valve provide a pressure difference whose readings are fed through a DAQ board into LabView with a custom program leveraging the mechanical energy equation to determine torque and horsepower. The pressure loss across the two transducers represents a head loss in the system, by calculating the other head losses due to fluid friction and the various fittings, then adding those to the variable head loss from the throttling valve, the amount of head, or energy, added to the fluid by the pump is determined. This allows the system to measure the power of the pump and therefore the engine driving the pump. With a known engine speed from the tachometer and a known engine power from the fluid loop, the torque of the engine is also determined. The dynamometer was calibrated and validated with a 5HP 3-phase electric motor driven by a variable frequency drive to get a known input power and verify the projected losses within the system. The system was then tested with two gasoline engines, one 7.5HP and one 10HP. Several trials were conducted with the electric motor and the gasoline engines to verify the repeatability and reproducibility of the system as well as the accuracy of the system. The student developed and built fluid friction dynamometer design cost approximately $1,600 - well below the price of “off the shelf” solutions. 

Presenting Author: Andrew Jennings Northern Michigan University

Presenting Author Biography: Andrew is a senior studying Mechanical Engineering Technology at Northern Michigan University.

Authors:

Andrew Jennings Northern Michigan University
Seth Norberg Northern Michigan University
Kollen Jansma Northern Michigan University
Jaden Knapp Northern Michigan University
Weilan Larose Northern Michigan University