Design intake air restriction of 20mm on and

Design & Analysis for Intake System of Formula
SAE Car

Prashant A Dhaware*,
Chetan Sumbare, Chinmay Sonawane,

Abhishek Rasane,
Mahesh Take

Faculty* &
Students

Mechanical
Engineering department, RajshriShaucollege of Engineering & Research,

Narhe, pune,Maharashtra,
India.

 

Abstract

Team IRON HEAD,
RSSCOER Pune University performed the study of intake restrictor design to
improve engine performance and increase team’s competitiveness at Formula SAE
competitions. Objective of this project was to optimize the venture type of
restrictor included in the intake system as imposed in the FSAE rule. Various
intake designs were studied like top/center feed intake, side entry intake, and
conical spline intake designs. The fluid flow through the intake was analyzed
using CFD flow modeling software. The CFD results observed the converging and
diverging angles of 12 degree and 6 degree respectively achieving minimum
pressure drop

 

INTRODUCTION

Formula
SAE is a student design competition organized by SAE International (formerly
Society of Automotive Engineers). The first competition was started back in
1979 after Mark Marshek, at Houston University, contacted SAE Department of Educational
Relations in 1978.

A
rule was imposed by FSAE rules committee for the intake air restriction of 20mm
on and below four stroke engines. The Engines used are limited to 610 cc
engines having an output of 15000 revolutions with 120 horsepower. Team Iron
Head has used dual cylinder, liquid cool 296cc engine having an output of
38.5bhp at 11000 RPM and torque 27N-m at 10000 rpm. The flow of air takes place
from the throttle body and the plenum of intake system before entering the
runner which feeds to the engine. The Internal Combustion Engine takes in air
from the atmosphere and the appropriate ratio of air-fuel mixture is combusted
into the engine cylinder. Air must flow from single 20mm restrictor to intake
manifold so engine have two cylinder and two throttle intake having 25mm
diameter of each cylinder. This drastic change reduces the air flow to the
engine thereby controlling its power output. The objective behind designing the
intake system is to allow maximum possible air flow with minimum pressure drop.9

 

Engine
Performance And Research

Engine
Specification

 

Sr.no

Parameter

Specification

1

Displacement

296cc

2

Max. power

38.5
[email protected]

3

Max. torque

27N-m
@10000rpm

4

Engine
description

Liquid cooled,
4 stroke Parallel twin

5

Cooling

Liquid cooled

6

Fuel system

Fuel injection
Ø32mm*2 with dual throttle valve
 

7

Ignition

Digital

9

Compression
ratio

10.6: 1

10

Bore

62mm

11

Stroke-

49 mm

12

No. of
cylinder
 

2

13

Power to
weight ratio-

223.83bhp per
tone

14

Torque to
weight ratio

156.97N-m per
tone

15

Specific
output

130.06bhp per liter

Table No. 1 Engine
specification

 

Fig1.
Manifold with Ø20mm air restrictor. 8

 

Intake
Restrictor

 

Fig
(2). Basic Design of Intake Restrictor

 

In order to limit the power capability
from the engine, a single circular restrictor must is placed in the intake
system between the throttle and the engine and all engine airflow passes
through the restrictor. The intake restrictor is a device adapting a venture
portion at its throat,            for the
increase of velocity of inlet air. The throat venture diameter is maintained at
20.0 mm (0.7874 inch) according to the rules initiated by SAE Supra .The
restrictor is a non-movable portion of the throttle barrel. The velocity of
charge in the intake system should not decrease to such limits so that fuel
will start falling out of suspension. But the design should be careful so that
fuel mixture is sufficient for supporting peal torque RPM. For 3 to 6 cylinder
engines the plenum volume of 0.8 to 1.5 works well while engines with 8, 10 and
12 cylinders run well with even lesser. But with the restrictor, the plenum has
to be slightly large. If the engine is left to the air purely higher RPM it may
suffocate.

Design Constants and Variables:

 Since the aim is to optimize the intake
restrictor, the mass flow rate calculation is to be done. Maximum flow rate is:

For an ideal compressible gas:

Where A = cross-sectional area at which
the flow is sonic, P0 is the stagnation pressure,T0 is the stagnation
temperature, R is the specific gas constant, and k = cp/cv is the specific heat
ratio of the gas.

The maximum flow rate can be expressed
in terms of inlet temperature Ti and inlet pressure Pi by expressing the
stagnation temperature and stagnation pressure as 

Where,

Vi is the inlet velocity.

Mass flow rate is maximum when M = 1. At
these conditions, flow is choked. The mass flow rate from above equation is
calculated using the following data values:

 M
= 1

 A
= 0.001256 m2 (20 mm restriction)

 R
= 0.286 KJ/Kg-K ? = 1.4

 P0= 101325 Pa

 T
= 300 K

Mass flow rate = 0.0703 kg/sec 5

 

Parts
and Assembly of Intake System

 

Fig.(3)Assembly of intake system 1

 

Parts: 1.Air Filter, 2. Throttle Valve,
3. Intake Restrictor, 4. Plenum, 5. Cylinder

 

Plenum:

In order to reduce the influence of the
restrictor, it is necessary to minimize the maximum instantaneous flow velocity
through it.A way to obtain this objective is to place a plenum chamber between
the restrictor and the engine. The plenum allows one to minimize the pulsating
flow through the restrictor. As a consequence the pressure drop at the
restrictor decreases and the mass flow rate elaborated by the engine raises
allowing growth of engine performance. 1

 

Discussions & Conclusion

FSAE is all about speed, acceleration
and economy. In this competition, all the teams are busy trying to utilize
almost a single horse power available even with the restrictor attached. This
gives rise to the increase in research and optimization of intake system
designs. The optimum solution is to achieve the maximum mass flow rate of air
through the flow restriction device. 
Venture serves the best design for this objective. It allows a maximum
flow rate of 0.0703 kg /sec of air flow to the engine.

 

 

 

ACKNOWLEDGEMENT

We would like to express my sincere
thanks to our friend Chetan petkar who helped us to research on this title
accurately, after lots of practice and hours put into it.  Sincere thanks to Prof. Prashant dhaware of
Mechanical Department for giving us the opportunity, for his guidance and
supervision in all respects of this paper.

 

REFERNCES

1.      
Giovanni Vichia, Luca Romania, Lorenzo Ferrarib,
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2.       Luca Romania,
Giovanni Vichia, Alessandro Bianchinia, Lorenzo Ferrarib, Giovanni Ferrara”Optimization
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Electronically Actuated”

3.       Abhishek Raj,
J.C. Mohanta, Bireswar Paul, Mohd. NayabZafar “DESIGN OF A NEW IMPROVED INTAKE
MANIFOLD FOR  F-SAE CAR” ISSN
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6.       “Pranav Anil
Shind, “Research and optimization of intake restrictor for Formula SAE car
engine” International Journal of Scientific and Research Publications, Volume
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7.       S N Waghmare, N
S Karekar, P PKarande,  S B Pandhare,
“Intake System of Formula SAE Car: A Proposed Model” International Journal of
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8.       Mindaugas
Melaikaa,b,*, Alfredas Rimkusa,b, Tadas Vipartasb ”
Air Restrictor and Turbocharger Influence for the Formula Student
Engine Performance”

9.       SAE
Supra Official Site

 http://suprasaeindia.org/

 

 

 

 

 

 

 

 

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