Exhaust and Muffler Design of a Formula SAE car

Design and fabrication of exhaust and muffler of a formula SAE vehicle • • •

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Gajendra Gulgulia 09BEM085 Manu Pant 09BEM031 Mohit Mundra 09BEM033 Project Guide: Prof. Thundil Karupparaj. R Program Manager, Energy Division SMBS, VIT.

LITERATURE REVIEW  KEY POINTS

1. The exhaust system was targeted for maximizing low rpm torque while maintaining a broad flat curve without significant loss of high rpm horsepower. 2. Considerable attention had to be given to the exhaust primary tracts, collector and silencer designs. 3. Effects of modifying the restrictor design, intake runner length, intake camshaft profile, exhaust geometry and silencer design were measured using a transient dynamometer. 4. Optimum design –short inlet manifold, long diffuser, reduced valve overlap. 5. Design ,development and testing of a restrictor for use in formula SAE racing.

KEY POINTS 6. Design objectives  – Increase air flow between a pressure drop of 5 to 15 inches Reduce pressure loss upon plenum entry. Minimize the effects of reversion. Develop a throttle body for minimal flow saperation. 7. A combined analytical CAE procedure and durability experiments are used to calculate the durability of complete exhaust system. 8. Durability issues associated with the exhaust system components such as hot ends bracket, converter cone pipe region ,exhaust pipe system, muffler pipe system, muffler hanger design, and residual stresses in the exhaust system assembly. 9. Aimed at raising engine power and drivability . 10.Ways to get engine power improvement are combustion improvement, the change of the cam profile, and supercharging. 11.Intake air collector and air restrictor redesigned in consideration of  installation

KEY POINTS 12.RLDA(Road load data acquisition) is one of the most important steps to verify exhaust system durability performance . 13. First a two degree of freedom system is analyzed; second , 2D and 3D beams sre studied. Then FEA comparison between body side input and exhaust side input are conducted for an exhaust system. 14.At idle engine speed, the exhaust discharge noise is influenced by resonances in the whole system, which is composed of connecting pipes and silencers. 15.The pipe resonance radiates a high level of low frequency discharge noise ,which is dominated by the low order harmonics of the engine firing frequency. 16.This low frequency noise deteriorates the vehicles interior noise level and quality.

FSAE RULES: The Problem Statement ARTICLE 3: EXHAUST SYSTEM AND NOISE CONTROL IC3.1 Exhaust System General IC3.1.1 Exhaust Outlet The exhaust must be routed so that the driver is not subjected to fumes at any speed considering the draft of  the car. IC3.1.2 The exhaust outlet(s) must not extend more than 45 cm (17.7 inches) behind the centerline of the rear axle, and shall be no more than 60 cm (23.6 inches) above the ground. IC3.1.3 Any exhaust components (headers, mufflers, etc.) that protrude from the side of the body in front of  the main roll hoop must be shielded to prevent contact by persons approaching the car or a driver exiting the car. IC3.2 Noise Measuring Procedure IC3.2.1 The sound level will be measured during a static test. Measurements will be made with a free-field microphone placed free from obstructions at the exhaust outlet level, 0.5 m (19.68 inches) from the end of the exhaust outlet, at an angle of forty-five degrees (45°) with the outlet in the horizontal plane. The test will be run with the gearbox in neutral at the engine speed defined below. Where more than one exhaust outlet is present, the test will be repeated for each exhaust and the highest reading will be used. IC3.2.2 The car must be compliant at all engine speeds up to the test speed defined below. IC3.2.3 If the exhaust has any form of movable tuning or throttling device or system, it must be compliant with the device or system in all positions. The position of the device must be visible to the officials for the noise test and must be manually operable by the officials during the noise test. IC3.2.4 Test Speeds The test speed for a given engine will be the engine speed that corresponds to an average piston speed of  914.4 m/min (3,000 ft/min) for automotive or motorcycle engines, and 731.5 m/min (2,400 ft/min) for “industrial engines”. The calculated speed will be rounded to the nearest 500 rpm. The test speeds for typical engines will be published by the organizers. IC3.3 Maximum Sound Level The maximum permitted sound level is 110 dBA, fast weighting. • • •

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Aim of muffler: -To meet packaging constraints -To provide required reduction in noise -To provide minimum back pressure Types of muffler -Straight through muffler(low B.P, low attenuation) -Resonating Chamber design(Higher B.P, better attenuation) -Reverse Helmholtz resonator

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PROJECT DETAILS: A STEP WISE Approach: 1. Design: a. Modelling b. Analysis c. Modification d. Finalization 2. Manufacturing 3. Testing: a. Flow Test b. Dyno Test c. Noise Test 4. Redesign-Repair-Retest(3 R phase) 5. Finalize and conclude

GANTT CHART

Initial Modeling

Initial practice simulation

REFERENCE PAPER

POINTS DERIVED

1.Exhaust system design for a four cylinder Engine- Badih Jawad,Christopher Biggs and Bradley Klein

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2.Experimental optimisation of manifold and camshaft geometries for a restricted 600cc four cylinder four stroke engine – R.H.McKee , G.McCullough,G Cunningham,J.O.Taylor.

3,4

3.An experimental approach to design ,build and test a throttle body and restrictor system for formula SAE racing.- Brooke Byam, Jackie Fsadni ,Allen Hart And Rachel Lanczynski

5,6

4.Structural durability evaluation of exhaust system components – Lakshmikanth Meda, Helge Lawrenz, Martin Romzek.

7,8

5.A study on intake and exhaust system of turbocharged engine under the regulations of formula SAE.  – Syuhei Yamamoto, Shinya Matsumoto, Tomoaki Kodama,Yasuhiro

9,10

REFERENCE PAPER

POINTS DERIVED

8.Model transient FEA study to simulate exhaust system road load test -Fulun Yang and Henry cheng.

11,12

7.Optimal design of the exhaust system layout to suppress the discharge noise from an idling engine.- C-Y choi, T-K SIM,S-H yang

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8.The Scientific Design of Exhaust and Intake Systems- Smith and Morrison