The team’s progress has consisted of contacting manufacturers, looking in the market for slip-on mufflers and selecting the optimal RPM for the engine’s performance. The team has completed research regarding the wave phenomenon scavenging where our findings led to a finalized exhaust formation of the headers leading to a 4 -to- 2 -to- 1 exhaust system. The connections of the headers will run through 3 collectors, as shaded in the following drawing, and will lead to one pipe where the single pipe leads to a slip on the muffler.
Figure1: Exhaust Dimensions Rough Draft
Team 8 has been able to get in contact with a possible manufacturer, Houston Muffler Shop. This meeting brought to the team’s attention the possibility of using galvanized steel as the material for the exhaust system, given that it is the material used by most welding facilities in Houston and it is more economical. If we decide to continue with the 321 stainless steel material, the shop is willing to weld the components together only if we provide them cut and ready to weld. They have also brought our attention to an easier and beneficial technique of welding where we could utilize v-bands to weld the components together through the v-bands. This would be beneficial given that it is easier to disassemble if any issues may occur. The muffler shop has also mentioned 4 different brands of mufflers available, but warned us to consider the standard muffler diameter size from the final prototype exhaust pipe diameter. Lastly, the shop mentioned they could include a hole in the mid pipe for the bung and include the necessary thread to insert the oxygen sensor.
Figure 2: Unconfigured V-Band used to weld exhaust extremities together
The team has selected to aim our design and results to function by considering an RPM in the 5500s. The endurance race will not lead the driver to stay at the highest RPMs the engine could endure, so the team decided to aim for an RPM that the driver will maintain in often.
The team is still in the process of selecting a muffler given that the material used might be replaced. The exhaust system must have the same material throughout each component to be welded together. However, the type of muffler that will be selected will still be absorptive, usually composed, given that it is the optimal option because it is the one that has the least impact on back pressure of the exhaust gasses.
Although the team is currently behind schedule, there will be more time allocated in the following week to finalize the remaining tasks.
The team will work on 3D modeling the exhaust system up until the end of the mid pipe using the diameters and lengths of the pipes calculated. The initial configuration will be based on the space available in the chassis and also on feedback provided from other subteam leads. By looking at where the midpipe will be ending at, the team will select a muffler to be purchased to finalize the entire exhaust system modeling.
Figure 3: Initial Exhaust header CAD
After this initial outline of the system has been determined, the team will perform CFD analysis and simulation using Ansys fluent to reiterate the design as necessary to achieve the backpressure desired for scavenging. This program is new for all members of the team so we will be basing most of our analysis on material found online and on feedback from our CFD professor Dr.Lee. Moreover, through this entire process of 3D modeling the exhaust system, the team will continuously communicate changes to our manufacturer to make sure our ideas are capable of being fabricated.
By the end of this upcoming two weeks, the team plans to be close or finished with a final design of the exhaust system intended to increase horsepower by 10% at 5500 RPM. If time allows the team will learn how to use a program named Ricardo wave to help get better approximations on the Boundary conditions that the headers will be undergoing to further input them into the Ansys simulation.
There are a few possible bumps on the road to the completion of the design. For example, as the team has a lack of hands on experience with creating CFD relevant CFD simulations, the team has begun to build a foundation of practice on familiarizing themselves with the software (ANSYS Fluent), but getting the background to make accurate assumptions in the creation of this software may cause a delay in the team’s schedule. To mitigate this, The formula exhaust engineers have contacted a University professor with extensive experience with the given software (The same professor that recommended the team to use ANSYS Fluent for the design/simulation aspect of this project)
In addition to a lack of familiarization with software, another issue the team has begun to anticipate is difficulty to find local tube bending shops that are willing to give out discounts to FSAE teams. Even though we have already considered paying full price for the welding and bending for the tubes, we would like to make the most of UH FSAE and their officers as a resource to find any good deals on the fabrication of our design if and when it is possible. If the team does not find any viable sponsorship option by the time the header and midpipe design is acceptably optimized (Mid December at max) the team will follow through with the initial plan to quote the bending and weld of the design from a steel shop at full price as originally planned.
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