Maximization of Flow through Intake

1
Maximization of Flow through Intake Exhaust
Systems

• P M V Subbarao
• Professor
• Mechanical Engineering Department

Use Complex Wave Gas Dynamics for effective
breathing.
2
Acoustic Theory of Piping

• The intake manifold to an internal combustion
  (IC) engine will consist of a network of
  interconnecting pipes.
• The lengths of these pipes, and to a certain
  extent their diameters, must be chosen carefully
  as they will determine the resonant frequencies
  of the manifold.
• When the engine is run at a speed where one or
  more of these resonances is excited, then both
  the volumetric efficiency and the intake noise
  level maybe affected.

3
Acoustic Modeling of Complex Piping System
Induction System Model
4
Build Considerations for Resonating Piping System

• Variable Length Runners for RPM matching
• Materials Selection Criteria
• Weight, Fabrication, Surface Finish, Heat
  Isolation
• Intake placement
• Isolate from heat sources (Engine, Exhaust,
  Radiator, Pavement)
• Fuel Injector Placement

5
Experimental Methods to Understand Resonant
Frequencies of Induction System
6
Modulation of Acoustic Waves
7
Pipe with Throttle
8
Junctions
The most complex cause of pressure waves is when
the intake valve closes. Any velocity left in the
intake port column of air will make high pressure
at the back of the valve. This high pressure
wave travels toward the open end of the intake
tract and is reflected and inverted as a low
pressure wave.
9
Central Theorem for Acoustic Design

• The tuning peak will occur when the natural
  Helmholtz resonance of the cylinder and runner is
  about twice the piston frequency.
• The Engine can generate highest Torque at turning
  peak conditions.
• The aim of acoustic design is to achieve tuning
  peak at highest speed or highest power
  conditions.
• Tuned port simply means that the intake runners
  are tuned to have highest volumetric efficiency
  at specific rpm range.

10
Acoustic Characterization of Components
Using Engelman's electrical analogy we can define
the system as a system defined by capacitances
and inductances.
11
Acoustic Modeling of Runner
Ideal Helmholtz Resonator
The theory behind what happens in the intake (and
exhaust systems) is called A Helmholtz
Resonator. Induction pressure waves can have an
effect on how well the cylinders are filled. It
can help (or hurt) power in a narrow rpm Range.
12
Primary Volume/Capacitance
13
Determination of Primary Capacitance

• The Primary Volume is considered to be the
  Cylinder Volume with the Piston at mid-stroke
  (effective volume).

• Writing Clearance Volume in Terms of Compression
  Ratio

14
Acoustic Modeling of Runner with Port

• For a single degree of freedom system

A1 Average Area of Runner and Port L1
LPort Lrunner K1 642 C Speed of Sound
15
Primary Secondary Induction Systems

• The prime system responsible for flow of air is
  called as primary system.
• The remaining part of the system, which is not
  actively feed the cylinder is called as secondary
  system.