The Exhaust System of the new Porsche 911 Carrera

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Darrell Merritt
8 years ago
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1 Januar 2012 Seite 1 von 25

2 38261 Ricardo User Conference 2012 Ludwigsburg, engineered for Emotions Dr. Ing. h.c. F. Porsche AG 30. Januar 2012 Seite 2 von 25

3 7th Generation Porsche 911 all new 911 generation increased engine performance and Effiency aluminium-steel body reduced weight enhanced emotional experience Nürburgring laptime 7:40 min Seite 3 von 25

4 Sound Sources of the 911 Exhaust Orifice Engine Mechanics Intake Orifice Seite 4 von 25

5 Development Targets for the Exhaust System characteristic 911 sound provide an optional sport exhaust system absence of acoustic annoyances like low engine speed booms reduced backpressure to increase specific engine power meet all global drive-by-noise targets weight reduction Seite 5 von 25

6 Package package space between engine an rear bodywork only system wrapped around the Engine completely different concepts in this package has been evaluated three different production systems to be offered: - base System for 3,4 litre - base System for 3,8 litre - optional sport exhaust system for both Seite 6 von 25

7 WAVE Usage evaluation of concepts exhaust orifice noise simulation sound evaluation by WAVE audio files torque characteristic of each variant considered decision of hardware variants engine with intake- and exhaust manifold modelled by powertrain CAE, using WAVE Mesher air cleaner and exhaust silencer system modelled by powertrain acoustics, using WB3D Seite 7 von 25

8 Baseline Exhaust Systems specific baseline exhaust systems for 3,4 litre and 3,8 litre Engine 3,4 litre: - single, oval tailpipes - duct routing and general layout carry over from previous system 3,8 litre: - double, circular tailpipes - engine performance + 15 HP over predecessor mainly by reduced exhaust backpressure - flap system - sound different to 3,4 litre system - avoid perceptible flap switchpoints - compensation of flap weight versus previous system Seite 8 von 25

9 3,4 litre Baseline System Model carry over layout with center pre silencer and main silencers right and left side silencer volumes, package and sound adapted WAVE used for - chamber layout - duct diameters and lenghs CAD WB3D WB Seite 9 von 25

10 3,4 litre Baseline System Orifice Noise Simulation microphone position: - right tailpipe - 25 centimeter, 45 degrees Simulation Measurement Seite 10 von 25

11 3,8 litre Baseline System Model flaps in pre silencer WAVE used for - definition of flap position, main or pre silencer - flow distribution between bypass and main duct routing - chamber layout - duct diameters and lenghs CAD WB3D WB Seite 11 von 25

12 3,8 litre Baseline System Orifice Noise Simulation Measurement Flaps open Flaps open Flaps closed Flaps closed switchpoint Simulation Seite 12 von 25

13 Sport Exhaust System impressive flat six sound, different from 3,8 litre baseline polished double, circular tailpipes flap system absence of annoying booms with open and closed flaps over entire engine speed range audible Sound step by open flaps optimised torque and power behaviour reduced weight versus previous sport exhaust system Seite 13 von 25

14 Sport Exhaust Concepts 1. Flow Cat > Side Silencer > Center Silencer 3. Snail System, long Tailpipe GT3 System, Flaps after Cat Turbo System, single big Silencer Seite 14 von 25

15 Sport Exhaust Concepts WB3D Models 1. Flow Cat > Side Silencer > Center Silencer 3. Snail System, long Tailpipe GT3 System, Flaps after Cat Turbo System, single big Silencer Seite 15 von 25

16 Sport Exhaust Concepts Orifice Noise Simulation 1. Flow Cat > Side Silencer > Center Silencer 3. Snail System, long Tailpipe high 4.5th order at low speeds high 1.5th order at low speeds 3rd order resonance, above target decreasing order level GT3 System, Flaps after Cat Turbo System, single big Silencer impressive Sound 3rd order at low speeds above target appropriate sound high 3rd order from 1500 rpm above target Seite 16 von 25

17 Sport Exhaust Production Concept pre silencer slpit in two volumes flaps in cross section between both volumes clear recognizable sound by interaction of both cylinder banks with flaps open high low speed torque by separation of both cylinder banks with flaps closed manifold, cat and main silencers kept from 3,8 litre baseline System very good correlation between simulation and measurements, even for higher engine orders Seite 17 von 25

18 Sport Exhaust Orifice Noise Simulation Simulation Measurement Flaps open Flaps closed Flaps closed switchpoint Flaps open Seite 18 von 25

19 Sport Exhaust Orifice Noise Simulation Simulation Measurement Flaps open Flaps open Flaps closed Flaps closed switchpoint Seite 19 von 25

20 Sport Exhaust Pressure Simulation pressure simulation of cross section, 3500/min Seite 20 von 25

21 Sport Exhaust Production System Seite 21 von 25

22 Sounds 3,4l Baseline 3,8l Baseline Sport Exhaust Seite 22 von 25

23 Summary three different exhaust systems has been developed aural emotions were enhanced by sound engineering different sound characters of the three systems were achieved a sport exhaust system was created, which is able to switch a bypass and a cylinder bank interaction simultaneously WAVE acoustics was useful to evaluate different exhaust concepts WAVE acoustic results were sufficient for concept and variant decisions weight of sport system was reduced by 5 kilograms Seite 23 von 25

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Absorption mufflers in exhaust systems. Rolf Jebasinski. J. Eberspächer GmbH & Co. Abstract

1 Absorption mufflers in exhaust systems Rolf Jebasinski J. Eberspächer GmbH & Co Abstract Absorption mufflers or combined absorption/reflection mufflers are an almost indispensable element of modern exhaust