1. Results : Design: Summary: As oil and gasoline prices continue to rise, along with their environmental concerns, the discovery of natural gas sources in the United States creates the opportunity to utilize natural gas as an alternative for transportation fuel This project relates to the means for delivering a portion of Compressed Natural Gas (CNG) or any gaseous fuel for use in an internal combustion engine through the use of a mass flow distribution device It is our goal to create a test fixture which involves the stepper motor provided by CTS Corp. that can control mass flow in a repeatable and accurate manner Schuyler Witschi (EE) Lianna Dicke (EE) Selden Porter (ME) Luke McKean (ME) Gas Flow Theory: The final design integrates a ball and seal valve operated by a push rod that rides a cam. The cam is driven by an automotive actuator that uses CAN protocol. Lifting the ball a known distance (a function of the cam profile and actuator position) results in a solvable choke area and mass flow rate. By measuring flow out of the device under certain conditions we could plot the position to lift graph of the device which can be used to tune it By 25% throttle opening, the lower value of target flow rate range for 60 psi was met. At the upper limit of the available flow measurement equipment, the flow was still in the target range. The cam profile can be tuned for different applications with different flow control requirements. To prevent leak, the ball is pressed into the seat with a spring. The spring, combined with the force from the pneumatic pressure differential, makes a positive seal. O-rings are used in all mating surfaces to prevent leak and provide adequate sealing. Cam Seat Ball Actuator The flow was determined to be choked due to its high pressure differential. The following formula was used to determine the effective valve throat area needed to meet the engineering requirements: Where A 0 is the effective throat area, m* is the mass flow rate through the throat, T 0 is the total temperature at the throat, P 0 is the total pressure at the throat, R is the specific gas constant, and γ is the adiabatic ratio of the gas. This assumes the flow is isentropic meaning it neglects viscosity and assumes there is no heat transfer in or out of the flow. Eng. rqmt. #ImportanceDescriptionUnit of MeasureTarget ValueMeasured Value ER19Accuracy of Position% of commanded value± 5< 2 ER29Repeatability of Position% of previous value± 5< 1 ER39Leak Rate of Devicesccm25200 ER49Operating Voltagevolts13.512 ER59Dynamic Range of Position Steps# of motor steps123>100 ER63Flow @ 4 bar-g (58 psig)g/s12-1816 ER73Operating Inlet Pressure Rangebar-g (psig)4 (58)1.7-4.1 (25-60) Will be acknowledged in the design: ER89Total Leaksccm0 ✓ ER99Open Response TimemsN/A260 ER109Close Response TimemsNA250 ER113Operational Temperature Range°C (°F)-40-85 (-40-185) ✓ ER123Burst Pressurebar-g (psig)TBD ✓ ER133Operating lifehrs10,000 ✓ ER141Compatible Engine Sizeliters5.7 ✓ Regulated Output Natural Gas Input Natural Gas