Final Design
Presented by: Chinaar Desai, Cassandra Moreno, Luke Bockman, Justin Moreno
Sponsored by: Triton Racing - UC San Diego’s Formula SAE Team
UCSD FSAE Engine Dynamometer Final Design
Final Design of Engine Dyno Test Bed
Overview
The dyno that was manufactured is a water brake engine dyno with functional requirements including: capability of measuring the power of a 90 kilowatt (kW) engine, measurability and recordability of revolutions per minute (rpm) and torque (Nm). The dyno test bed provides a real-time visualization of collected data, and allows the engine to be tested under various conditions for differing durations. Reliability and safety were also critical to the project success. The dyno components consists of: a welded steel frame, a manufactured aluminum water brake, a water recirculation system, and a data acquisition system.
The welded steel frame was manufactured after completing a finite element analysis of the CAD model and determining that the frame had a maximum deflection of less than a millimeter. In addition, with a load case set for 1300 N, the frame had a factor of safety of 4. This frame includes four subframes: base, main, engine, driveline subframes and a control panel. The frame also includes sheet metal protection against high speed rotating components. Also, the frame is powder coated for corrosion resistance and durability, and is easily mobile with lockable casters.
Engine Dyno Final Design
Annotated CAD Model of Final Design
Water Brake
The custom manufactured aluminum water brake was modeled after a Stuska Dynamometer XS-111 water brake. It has the ability to absorb and dissipate 90 kW (120 hp) of power continuously and rotate at speeds between 1500 and 6000 rpm.
This water brake includes a rotor, two stators, a shaft, two trunnions and a torque arm. The rotor was designed with a diameter of 24 cm, giving a theoretical power limitation of 200 kW. The rotor interfaces with the water brake shaft through a 80 micron interference fit. The stators provide a chamber for the rotor to operate, a surface by which viscous and shear forces will accumulate and provide a measurable torque corresponding to the output of the engine being tested. There are two trunnions, one of which holds a single 6006 ball bearing and the second holds two 6006 ball bearings. The torque arm reacts to the torque produced by the water brake such that the system is fully constrained and purely in compression.
Section View of the Water Brake
After completion of manufacturing the water brake, the rotor was coated with type-2 anodizing to prevent galvanic corrosion and was also professionally balanced for high speed rotation.
A section view is provided on the right to give a better view of what the water brake is composed of on the inside and how water enters in order to load it.
Water System
The water circulation system serves as a cooling system and to load the water brake. It includes a reservoir, radiator, circulator pump, pump filter, two gate valves, and flexible PVC tubing. The reservoir is polypropylene and has a volume of 26.5 L and the radiator is an automotive type after-market radiator with a core size of 66.67m x 32.385m x 4.445m. The pump is a TACO 0011 circulator pump with the capacity of 1.4 L/s at 3 meters of head. A Watts brass pump filter with a wye- pattern lead free cast strainer was chosen to prevent any large debris from entering the pump and causing damage. Gate valves were chosen to provide finer control of the flow to and from the water brake. The entire water system is plumbed with high temperature resistant flex PVC tubing.
Data Acquisition & Visual Interface
The data acquisition system (DAQ) allows for data collection and visualization. The goal was to use sensors to measure torque and rpm and calculate engine power using the equation:
Final Water Brake Design
Final Water Re-circulation System Design
LabVIEW Interface for Dyno Operator
A myRIO-1900 DAQ was donated to the project by National Instruments, and was programmed through LabVIEW by the team to collect and store data from four waterproof thermistors, a Hall-effect sensor rpm sensor, and an S-Type load cell. The four waterproof thermistors are Sparkfun DS18B20 sensors used to measure temperature at critical locations: inlet of the water brake, outlet of the water brake, reservoir, and at prior to the engine radiator. The Hall-effect sensor is a Littelfuse Hall-Effect Sensor - 55505 implemented on the driveline and measures up to 7500 rpm. The load cell incorporated is an AnyLoad NH-500 S-type that is rated for a capacity of 224 kg. The load cell is mounted on the torque arm, 0.1524m (6 in.) away from the rotational axis of the water brake, and is used to measure the torque of the engine.