So far, the team has completed a final 3D model outline of the exhaust system, Selected a muffler to be purchased off the market, and the team has Started contacting manufactureres to create plans for manifold and mid-pipe fabrications.
currently, The 3D model has been completed and is undergoing CFD studies on Solidworks' flow simulator. The team has decided to utilize a Stainless Bros muffler made of 304 stainless steel and is 17 inches in length with inlet and outlet diameters of 2.25 inches.
The team has also requested a quote for manufacturing price for the 4 outlet engine coupler from the Ultimate Precision Tech and are waiting for them to get back with the exact price. The estimated price would be around $300. This is more than what the team expected but given that the welding of the different parts of the exhaust is going to be provided free of charge there won’t be a need to increase the budget just yet.
The main goal for the design was to boost engine horsepower by 10% to achieve an acceleration advantage during curves at the FSAE competition. At the beginning of the design process, the team decided to aim for an increase in engine performance in ranges between 5000 - 8000 RPM after reaching the conclusion that the car will not be reaching high RPMs due to the many curves and corners present in the track. After working around the formulas found in the book Performance Tuning in Theory and Practice Four Strokes from A.Graham Bell, we finalize a design intended to increase torque outputs at 5500 RPM. The final design was eventually governed by the dimensions from the engine exhaust ports, and the available space where the exhaust midpipe and muffler could fit. Knowing these constraints helped the team decide what type of diameters and pipe lengths were the optimal choice, hence, to what RMP could we be expecting an increase in Horsepower. The material selected(SS 321) for the design was based on its thermal properties and its availability to the team.
Based on the team’s Computational Fluid Analysis (CFD), the team has concluded that the design of the collectors which are placed between each significant exhaust component successfully creates a decrease in pressure. This behavior is desirable because as a result it creates a standing wave behavior as the exhaust gasses flow through the system.
Due to the complexity of using the program Ansys for CFD purposes, the team looked for alternative programs and decided to perform the same analysis using Solidworks. After studying about the CFD simulations offered by SolidWorks and Ansys, the team concluded that the precision of this analysis relies on how closely the assumed boundary conditions imputed into the CFD align with reality. Our simulations currently present a variety of errors due to our imputed conditions, moreover our initial guesses for the boundary conditions in respect to volumetric flow rates, pressure and temperature were vaguely obtained from videos of other already preformed simulations. The team plans to continue their research efforts to acquire a more accurate approximation of the boundary conditions, more specifically to the conditions the engine would be experiencing at 5500 rpm.
In coordination with the UH FSAE powertrain team, we were now given expected available space at the exhaust ports of the engine for us to fit the exhaust headers. As shown in the image, our primary pipes go past the available space given, therefore the team will redesign the configuration of the primary pipe headers to avoid interference with any other component of the car.
Before the spring 2024 semester begins, the team will finalize the exhaust system prototype design. Additionally, the team will have completed a comprehensive simulation using Computational Fluid Dynamics [CFD] to analyze the proposed exhaust system design and correct our model based on the results. Which is a crucial goal needed to begin the manufacturing process on time or with time to spare. For the validation preparations, the team will have in hand the necessary measuring equipment, at an economic price. This includes an infrared camera, infrared gun, decibel meter, torque sensor, and a hall effect sensor, which will be utilized to test engine, sound level, and temperature gradient performance. Furthermore, the team will also have a stock exhaust system ready for the key testing parameters to have as our baseline data and compare with them to the prototype results. Lastly, the team will have a finalized plan with the company that will manufacture the components and where the rest will be purchased from based on the sponsors, budget, and time.
Comments