• Subject Name : Engineering

Table of Content

Introduction and background

Methodology

Result and discussion

Conclusion

References

Introduction and Background on Air Intake and Exhaust System

In this era, motorsports activities have become one of the primary places of interest of many human beings throughout the globe. For many companies, it's exceptional opportunities that includes various kinds of activities like- speed oriented, simple road vehicle or alltrain vehicle, economic fuel oriented or any other criterion. It involves a great challenge to the engineers to overcome all the obstacles. If we take an example of India, basically there are two types of student-level events for formula-style car race which is SUPRA and FDC. 

The idea behind such events is to contract a design crew or team for the improvement as well as the development of a small formula-style car race by means of fictional manufacturing agency after satisfactory fulfillment of required desires. These designed cars will be judged on the basis of its quality and defined parameters for the better market product. These cars are constructed and manufactured only for tested the event site for encouraging better problem-solving techniques. Also, such cars are used for the racers to train them in their learning phase.

In automobile, air intake and exhaust system plays a very important role in different industries. Air intake system is used to bring in the air from surrounding of vehicle for internal combustion of engine. Oxygen is needed for a complete combustion, in the absence of enough oxygen, incomplete combustion takes place.

4CH4 + 7O2 → 2CO + 2CO2 + 8H2O

Due to this incomplete combustion some hazardous gases are generated like carbon monoxide (CO) which may increase the consumption of fuel so the fuel efficiency of an engine has reduced. For uniform distribution of oxygen throughout the combustion chamber, air intake system is needed. Intake system provides the power and efficiency of a vehicle so it is necessary to ensure a better engineering to boost up its basic properties. An efficient air intake system reduces the turmoil and minimizes the flow of air as per the requirement for the combustion chamber.

Functions of Intake system:

  • Supply enough oxygen into the combustion chamber to burn the fuel.
  • In the case of multi cylinder, supply uniform oxygen in each cylinder.
  • Purify air.
  • Provide necessary pressure and temperature for reaching the air into combustion chamber.

Air contains extra particles and contaminants which may affect the fuel combustion and the efficiency of the vehicle. Some intake systems are highly complex and use intake manifolds to distribute the air or fuel uniformly. Apart from it, if air is cool then combustion cannot be started easily or if temperature is high then there will be the case of pre ignition. Intake flow should be appreciably smooth not pulsating so it will restrict the noise and resonance.

Air intake system has three main parts which as follows:

  • Throttle body
  • Mass flow sensor
  • Air filter

An exhaust system takes out the wastage and other combustion products from the engine which generated by the combustion process. It also plays a major role in minimizing the noise, smoke and pollution that helps to make the environment clean. A properly maintained exhaust system is essential to operate a system smoothly. Combustion chamber should be completely empty so any by product gas of combustion process is not remain in the chamber. Secondly, gases should be made less hazardous at the time of outlet.

Functions of exhaust system are as follows:

  • Collect the gases form every cylinder in a multi cylinder system and release them in environment.
  • Slow down the noises of released gases to reduce the noise pollution.
  • Slow down the velocity and temperature of gases before releasing them into environment.
  • Convert the more hazardous gases into less one.
  • Don’t let the air and gases of environment back into the combustion chamber.

Earlier air intake systems consisted of plastic intake tubes and a cone shaped air filter that was made up of cotton gauze. With the technological advancement and ingenious engineering intake and exhaust systems are now in with great power and efficiency which gives the reinforcement to the vehicle by different kind of coatings. Intake systems are now available in metal tubes that allow the greater degree of customisation.

In automobile industry the air intake and exhaust systems market can be classified by type, application and geography. As it is said that necessity is the mother of invention so we have the formula one (F1) engines in the automobile industry. It is different in many terms like speed and the pressure of intake system. F1 engine has supreme speed about 6000 rpm that is beyond the limit of normal engine. This needs different techniques and engineering to built a F1 intake system.

Increasing demand of innovative ideas coupled with increasing production of vehicles and development in the automotive sector across all over the world is propelling the growth of global air intake systems market. Moreover, in the upcoming years there will be exponentially increment in applications of hybrid or F1 air intake systems that take the growth of automobile market to a new height.

There is a comprehensive evaluation of formula one intake and exhaust system and normal a normal intake system of an engine in this report. It has qualitative and quantitative data about the differences of both via in-depth. The projection is derived using literature, assumptions and research methodologies.

Literature Review of Air Intake and Exhaust System

In “Development of induction and exhaust system in third era Honda formula one engine” Ken Nishimori et al defines the necessary torque characteristics at low and medium speed in formula one and it’s important to design as a technique for their enhancement. To predict dynamic characteristics CFD is used. They develop the production techniques to shorten the time require to optimize the power characteristics.

In “Measurement of the effect on brake performance of the intake and exhaust system components in a motorbike high speed racing engine” Massimo Masi presents the performance measurement for a formula one (high speed) racing bike engine. In this he is presenting the assembly of each component belongs to intake and exhaust system. They investigate the effect of these components on the efficiency through different tests.

In “Development of a new air intake and exhaust system for a single seat race car” Damien Kennedy presents the design, analytics and noise emission testing of air intake and exhaust system for a single seat race car.

In “Influence of intake tumble ratio on general combustion performance, flame speed and propagation at a formula one type high-speed research engine” Thorsten Pfeffer et al showed the two different intake tumble ratios impact on the other parameters of combustion. The two zone combustion model was used for heat release and flame speed calculations.

In “Virtual engineering of formula 1 engines and airboxe” B. D. J. Mayne et al search for increased on-track speed, Formula 1 engine and chassis designers strive to maximise engine power. Computer co-simulations that couple a one-dimensional engine model to a three-dimensional computational fluid dynamics model of an airbox offer significant potential for optimising the design of engine and airbox packages.

Melaika et al. showed the effect of different air inlet restrictions on engine performance of Formula Student car engine using AVL BOOST numerical simulation model and the research was carried out on restrictor diameters, which varied from 15 mm to 60 mm. The smaller intake manifold pipe diameter increased hydraulic resistance of air intake and worsened therewith cylinder volumetric efficiency that resulted in lower engine power and higher brake specific fuel consumption.

 Mohamad et al. studied the effect of Ethanol-Gasoline blend fuel on engine power output and emissions. Their results showed great improvement in combustion process and exhaust gas characteristics.

Mohamad and Amroune used computational fluid dynamic (CFD) tools to describe the flow effects on engine exhaust chamber acoustic level and showed the transmission loss of muffler at different frequencies using 1D boost solver.

Abdullah et al. studied the engine performance in term of fuel consumption. Exhaust emission was influenced by the air intake pressure. The experimental results carried out demonstrated that the air intake pressure was influenced by the degree of opening throttle plate and venturi effect that draws the fuel to the combustion chamber in a carbureted engine. Without the air filter, the combustion process is improved due to a higher air intake pressure that transforms more fuel’s chemical energy into heat energy thus raising the exhaust gas temperature above values obtained with an air filter.

Mohamad et al. used a transfer matrix method (TMM) to perform the transmission loss of a muffler and the algorithm can also be used for other parts of the exhaust system. The result of their study of an existing muffler was compared with vehicle level test observation data. The transmission loss was optimized for new muffler design, while available literature played an important role in validation of obtained results.

Acquati et al. used mass and momentum balance equations to model the airflow and pressure around a nominal operating value computed using mean value models for intake system of a spark ignition engine.

Claywell et al suggested that in such events, distinct types of intake arrangements used. For a variation of volumetric efficiency, conical spline intake system has been used as compared to every cylinder and performance of the engine among all three types of intake concepts.

 Han-chi and Hong-wu suggested distinct types of optimization techniques used for both air exhaust and air intake systems. For designing air intake, nowadays orthogonal array testing has been used. Because of its inertia, it was assumed that the air inside the system, is sloshing from side to side and bouncing within the resonant cavities as a end result expansion and compression waves are passing via the pipeline, because of collision with open and closed ends, it gets reflected and also due to changes in the cross sectional area of the pipeline.

Hartmen and Jeff suggested that performance of the engine of JH600 motorcycle could be optimized with the help of energy balance equation for the complete system and for remaining section of the engine, mass balance could be used.

It was considered that the conservation of mass, momentum and energy equations requires in the approximated direction considering average of flow for the simulation of 1- D flow as per the Michael.

Methodologies of Air Intake and Exhaust System

Different researchers adopted the different approach and methodologies to model the formula one air intake and exhaust system. Traditionally, one dimensional (1D) simulation tools is used to optimize the design of multi-cylinder engines to replicate the uneven gas flow through the ducting of engine. With the help of these tools of simulation one can approximated the entire engine flow system that can be collected as of interconnected 1D Sub systems. This is the best technique when the flow losses meticulously expressed in one dimension.

Virtual 4-Stroke 1-D Engine Flow Diagram

Flow and flow losses are the parts of manifolds and inlets. These type of approaches used for the one dimensional modelling but when the case is different for the 3 dimensional (3D) modelling as it become little complex and 1D modelling will no longer valid, this 3D technology of modelling is used in air boxes of formula one engines. So to replicate the 3D model of engine computational fluid dynamics (CFD) is the most capable to model the engine and inlet system in three dimensions but it has some restrictions in terms of solution time. These restrictions can be solved by co-simulations between one dimension simulation and three dimensional computer fluid dynamics (CFD) packages and provide an attractive correlation to model the 1D and 3D individually. Currently this capability is offered by virtual-4 and fluent.

3D Fluent CFD Model of Airbox

In another research different types of analyses and modelling were used to design an engine with a better performance. In this research FEA analysis showed the best suitable air intake designs to distribute the air more even. To justify the results of FEA analysis dyno testing were done subsequently. For ensuring the issues of rigidity and strength of ABS material that is used in rapid prototype, physical testing was done. In formula one speed is the main asset of the engine which shows by the high RPM. At high RPM some vacuum is created due the contraction of walls of the intake system that makes the difficulty in generating the intake system from a number of assemblies sealing. Due to this drawback a different manufacturing approach is recommended to be used such as carbon fibre or plastic moulding. Major progress in recent years has been made by introducing nanofiber filters in engine system that increases the efficiency of engine and permeability than the traditional cellulose filter. Lubrication is essential for metallic moving parts of engine, for this purpose oil coating is done in the top of the parts of engine. Microscopic airborne particles can damage the film easily due to which the intake process become more rigid without any smoothness. This can be caused the less efficiency and lower the speed and power of the engine. To fulfil the requirement a new modelling is necessary with a high precision of diesel engine. To meet the stringent emission norms it needs 15000 L of air per unit fuel consumed. For keeping the purity of air and fuel in the intake system of engine meticulous filtration is necessary.

To achieve this fine filtration traditional approach of cellulose media filter cannot be sufficient. So a new approach to reinforce the filtration process a polyacrylonitrile bases nanofiber is used. Electro-spinning process is used to synthesis this nanofiber. Particular diameter of nanofiber is used to enhance the quality of intake system which is confirmed by scanning scope microscope image and 2D and 3D modelling is done with the help of this data. The trend of modelling the miniaturized model in filtration application and analysis using computational fluid dynamics has some restriction due to which it is limited research till now. The objectives for developing a formula one engine are to analyze variation of different properties of the inner engine like pressure drop and quality factor for different applications of automotive filtration. Ansys fluent analysis is used to calculate the pressure drops across the thin layer of nano-fiber filter, traditional fuel filter and double layer nano-fiber filter. Segregation of the particles which can damage the lubricating layer can be done through electro-spun nanofiber filter that is beneficial for the longer lifecycle and higher performance of an engine. Layers play a vital role in the process of filtration. In this aspect multi layers are better than the single layer. A single layer of polyacrylonitrile nanofiber filter is capable to force a minimum pressure drop that will result in higher quality factor for filtration applications. Pressure drop increases as the number of layers of nanofiber increases compared to conventional filter.

The air intake system consists of an inlet nozzle, throttle, restrictor and air box and cylinder suction pipes. The design and optimization of components is done by using CFD numerical simulations during the. Two main steps are to model the design of the air box and match it with the optimization of suction pipe lengths to torque over the entire range of different operating speeds. The software AVL-Boost is used to intake system was assessed acoustically and simulated by means of 1-D gas dynamics. To save a huge amount of time and resources before a new prototype intake manifold is built. New models enhance the quality of simulation in compared to AVL-Boost models.

Flowchart of the design and optimization process 1D model of the Honda CBR 600RR (PC 37) engine.

Result & Discussion on Air Intake and Exhaust System

By all researches, Software calculations and multi-iterations it is showed that a short runner impact a negative effect onto the air delivery in intake system. With this latest design, the airflow would be turbulent or noisy when entering the cylinder due to the uneven distribution of air which intake through the system. Due to this power delivered by the engine is decreased which lower the efficiency of the engine.

Noise or turbulence decreases the overall efficiency of engine so the noise test of the system will be done when the car is not in the moving position and it is also necessary that gear lever is not also in the working mode. To measure the sound level, device that will be a microphone in free field is placed behind the exhaust outlet about 1 m distance and there should not be any object or obstacle in between them. If there is more than one exhaust present in the system then the previous test is done on each and every exhaust and the maximum reading within all exhaust will be the final value of result. An average piston displacement that will be considered in specific value is about 914.4m/min and this is the required value for the noise test for the efficient engineering and industrial purpose. The highest permissible sound level for a test engine speed that is governed by the event committee is 110dB. That is the requirement of the test because as the rpm increases noise and turbulences also increases. Let’s say 11000 rpm is required so the noise level should be less than the 110dB.

In other research to validate the design by an analysis of CAD model of the system are carried out. Direction of flow is shown by the velocity vectors which take inside of intake and exhaust system. The air which comes in the intake system should have the particular velocity so this analysis shows the values of velocity of air and the gases came out from the exhaust at the inlet and outlet of the system.

There are various types of the automotive intake system, these are:

  • short pipe intakes
  • cold air intakes
  • ram air intakes

Short pipe intakes: In short pipe, intakes aluminium pipelines and very high flow filter has been used, which provides the better engine power at very higher RPM. It also enlarges the flow of the air into the vehicle’s intake manifold. It has disadvantages also that instead of the cold air, it store the hot air from under the hood of the vehicles, which is dense in nature and at the end the power of the engine is quite lesser as compared to other.

Cold air intake: If we talk about the cold air, it is better than complex compared to short pipe intakes. Also it pull out the cold air outside from the engine as the name suggest, due to which engine burn more fuel hence generate the more and more power.

Ram air intake: The most complex and difficult type of intake is ram air intake. It also draw he cold air same as the cold air intake systems. It is complex due to extra collector. Whenever a vehicle moves ahead, it withdraws the extra air. This ram air intake system helps to generate more or maximum power in car when it moves faster, it pressurizes the intake charge.

Conclusion on Air Intake and Exhaust System

Aerodynamics

A normal engine needs some technical persistence and a particular pressure mainly for the effect of air flow in intake system as it will not affect the motion of car adversely. In case of formula one aerodynamics plays a vital role so the automobiles are designed to make full use of airflow around it. As the applications are different of an F1 and normal engine so the F1 automobile’s body is streamlined so that there’s minimal drag at high speeds. It should be make sure that as speed increases the down pressure on the automobiles also increases effectively.

Engine

Engine of road cars or say a normal engine is engineered by focusing on reliability and robustness for a long service life about 15-20 years. Due to these demands engines are much heavier and contain less power in comparison to their weight. While an formula one engine needs more power as the service life is not a major concern. The main application of formula one engine is to provide the speed. According to Colin Chapman, “The ideal grand prix car would win a race and fall apart immediately after taking the chequered flag, having pushed every one of its mechanical tolerances to the absolute limit.” Therefore, every engine component is designed to ensure that its performance is not limited by the extra weight.

Dynamics

On a dynamic automobile object such as car different forces act like steering, braking and acceleration etc. It is assumed for the ease that centre of gravity is the main force due to which all are acting. In case of normal intake system automobiles, centre of gravity is far from the ground, moment is also higher. On the other hand formula one is extremely low slung so it has a centre of gravity close to the ground to help the efficient dynamics. Position of centre of gravity is the main point which causes the convenience loss moment to overcome the problems like rolling and pitching.

While in formula one not only the centre of gravity but also the damping ratio is also in the critical region to make sure the unsprung mass settle down in no time so there is the minimum losses of traction. This is the reason due to which ride is very uncomfortable but as there is the matter of performance not the comfort.

Braking Performance

In a normal intake and exhaust system many features are incorporated like ABS, EBD etc but formula one is not featured with all these driver’s aids. In case of normal automobiles active and passive safety is the main concern for users while in the case of formula one it’s all about the user who is going to handle that. There is no issue of safety. User has to decide that how it should be used. As in formula one the pressure and the temperature are the key features so there is advance type of brakes in that without fading.

Acceleration Performance

Formula one engine needs more acceleration as they are meant to perform in a particular field at a very high speed while a normal has just to carry the user from one place to another, Since formula one is needed to start quickly and bent at a sharp edge with a great speed, acceleration is the main in role. An average car requires 8-12 seconds to accelerate whereas formula one needs typically accelerates 0- 100 km per hour within few seconds on the different tracks.

Wheels / Tyres

As speed is the main feature of formula one so everything should be as light as possible. A huge force needs to be applied for greater mass so more power is required to stop a huge mass. When the cost is not the concern, to make a great balance between weight and strength low unsprung mass is used and the wheels are made up of magnesium. An impressive grip level of wheels is very important to achieve a high speed with power break. The life time of wheels is not more than a race.

While we concern about the road cars, safety, cost, material and power etc are the key features that play a great role to make it friendly and durable. Life time of wheels should be as more as possible.

References for Air Intake and Exhaust System

[1] Claywell M., Horkheimer D., “Improvement of Intake Restrictor Performance for a Formula SAE Race Car through 1D & Coupled 1D/3D Analysis Methods”, SAE 2006 Motorsports Conference, 2006-01-3654.

[2] HONG Han-chi, HUANG Hong-wu, and BAI Yi-jie, “Optimization of Intake and Exhaust System for FSAE Car Based on Orthogonal Array Testing”, School of Physics and Mechanical &Electrical Engineering, Xiamen University, China Mechanical Department of Xiamen University of Technology, China

[3] Hartman, and Jeff, “How to Tune and Modify Engine Management Systems”, 2003

[4] Delaney, and Michael, “Intake Manifold Tech: Runner Size Calculations”, www.teamintegra.net. [Online] 30 09 2002.

[5] Murray N., Clement A., Surgenor D., and Elrashidi K.,“SAE Air Intake, Exhaust & Engine Tuning”, Department Of Mechanical Engineering Dalhousie, Thesis

[6] Ryan I., Christopher B. W., “Design and Manufacture of a Formula SAE Intake System Using Fused Deposition Modeling and Fiber-Reinforced Composite Rapid Prototyping”, Journal, Vol. 16 Is: 3, pp.174 – 179.

[7] John Wall, “Dynamics Study of an Automobile Exhaust System”, 2003, Department of Mechanical Engineering, Blekinge Institute of Technology SE-371 Karlskrona, Sweden.

[8] Kennedy D., Woods G., and Forrest D., “Development of a new air intake and exhaust system for a single seat race car”. Dublin Institute of Technology, Thesis.

[9] Jianwei T., “Design of Automotive Helmholtz Intake Resonator Based on 1D /3D Models Coupling Simulation”, Automotive Engineering, 29, 10, (2007).

[10] 2011 Formula SAE Rules. http://students.sae.org/ competitions/ formula series/rules/ 30

[11] M.A. Ceviz. “Intake plenum volume and its influence on the engine performance, cyclic variability and emissions”. Energy Conversion and Management, 48, 961–966 (2007).

 [12] Kia Bauer. Orthogonal Array Testing Strategy. www.tcqaa.org laywell, Mark, Horkheimer, Donald and Stockburger, Garrett, Investigation of Intake Concepts for a Formula SAE Four Cylinder Engine Using 1D/3D (Ricardo WAVE-VECTIS) Coupled Modelling Techniques. 2006, p. 24.

[13] Melaika, M., Rimkus, A., Vipartas, T., 2017, Air restrictor and turbocharger influence for the formula student engine performance, Procedia Engineering, 187, pp. 402-407.

[14] Mohamad, B., Szepesi, G., Bollo, B., 2018, Review Article: Effect of ethanol-gasoline fuel blends on the exhaust emissions and characteristics of SI engines, Vehicle and Automotive Engineering, 2, pp. 29-41.

[15] Mohamad, B., Amroune, S., 2019, The analysis and effects of flow acoustic in a commercial automotive exhaust system, Advances and Trends in Engineering Sciences and Technologies III, Proceedings of the 3rd International Conference on Engineering Sciences and Technologies (ESaT 2018), September 12-14, 2018, High Tatras Mountains, Tatranské Matliare, Slovak Republic, pp. 197-202.

[16] Adbulleh, N.R., Shahruddin, N.S., Mamat, A.M.I., Kasolang, S., Zulkifli, A., Mamat, R., 2013, Effects of air intake pressure to the fuel economy and exhaust emissions on a small SI engine, Procedia Engineering, 68, pp. 278-284.

[17] Mohamad, B., Karoly, J., Kermani, M., 2019, Exhaust system muffler volume optimization of light commercial passenger car using transfer matrix method, International Journal of Engineering and Management Sciences (IJEMS), 4, 132-139.

[18] Acquati, F., Battarola, L., Scattolini, R., Siviero, C., 1996, An intake manifold model for spark ignition engines, IFAC Proceedings, 29(1), pp. 7945-7950.

[19] Winterbone, E., Pearson, R., Horlock, J., 2000, Theory of engine manifold design: wave action methods for IC engines, Professional Engineering Publ. London.

[20] Byam, B., Fsadni, J., Hart, A., Lanczynski, R., 2006, An experimental approach to design, build, and test a throttle body and restrictor system for Formula SAE racing, SAE Technical Paper 2006-01-0748, SAE World Congress, Detroit, MI, USA.

[21] FSAE MQP, 2011, Retrieved from http://moorsportsspares.com/file/2011_ttx25mkii_e.pdf (last access: 15.07.2019)

[22] Jawad, B., Lounsbery, A., Hoste, J., 2001, Evolution of intake design for a small engine formula vehicle, SAE Technical Paper, 2001-01-1211, SAE World Congress, Detroit, MI, USA.

[23] Shelagowski, M., Mahank, T., 2015, CFR Formula SAE intake restrictor design and performance, Proceedings of the 2015-ASEE North Central Section Conference American Society for Engineering Education.

[24] Tatschl, R., Schneider, J., Basara, D., Brohmer, A., Mehring, A., Hanjalic, K., 2005, Progress in the 3D-CFD calculation of the gas and water side heat transfer in engines, in 10. Tagung der Arbeitsprozess des Verbrennungsmotors (Proc. 10th Meeting on the Working Process of the Internal Combustion Engine), Graz, Austria.

[25] Vol. 111, Section 3: JOURNAL OF ENGINES (2002), pp. 643-656

Remember, at the center of any academic work, lies clarity and evidence. Should you need further assistance, do look up to our Engineering Assignment Help

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