SARM Engine - A new concept of Concentric Rotary Engines

DEPARTMENT OF MECHANICAL ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING VISWAJYOTHI COLLEGE OF
ENGNIEERING AND TECHNOLOGY
Guided By:- Presented By:-
A STUDY ON A NEW CONCENTRIC
ROTORY ENGINE
AJO ISAAC JOHN
ASST.PROFESSOR
ME Dept.
ANUROOP PA
REG NO: VJC15ME029
ROLL NO: 15

VISION AND MISSION
DEPARTMENT
 Vision :
• “ Moulding socially committed engineers capable to meet the global challenges in
the mechanical engineering stream”
 Mission :
• To provide ample facilities to foster excellent ambiance for teaching , learning
process in the department.
• To enhance the creative ideas, analytical talents and soft skills in the students to
cope with emerging trend in technical field.
• To enable the students to meet real life problems in mechanical engineering with a
zeal to human and ethical values.
2

OBJECTIVE
To study the principle and working of basic rotary engines
To study the new SARM rotary engine in contrast with others
To study the advantages and disadvantages of the mentioned engine
To observe the impact of the mentioned engine in the society and technological
world
3

In general, there are two main types of internal combustion engines: the reciprocating and the rotary
engines.
On the one hand, apart from the technologies that are not yet in the market, the core internal combustion
engines Research and Development is mainly related to the reciprocating engine improvement.
One of the core disadvantages of reciprocating engine is the mechanical system responsible for the
conversion of the reciprocating to rotational motion.
On the other hand, the similar research in rotary engines is limited. It solely focuses on the only
commercially available rotary engine: the Wankel-type engine
INTRODUCTION
4

INTRODUCTION
Here the idea is an innovative type of rotary engine and its possible contribution to a significant
increase in thermal efficiency and power density.
The main idea behind the present configuration is in envisaging an engine that avoids the drawbacks
of existing devices, leading so to a more efficient and environmental friendlier source of power
production.
The utilization of a modified Atkinson thermodynamic cycle allows a remarkable efficiency
improvement at a theoretical level.
As spark ignition (SI) engine efficiency is 32 to 35%, the Atkinson-type engines have efficiencies
near 40%
5

Table 1 : Modern technological developments in ICE
Recent Advancements
6

THE CONCENTRIC ROTARY ENGINE
7
Fig.1 The concentric rotary engine

Working Principle
8
Fig.2 Separate Chamber Concept
A compression chamber (CPC = Compression Chamber) is
necessary for the ambient air to enter and get compressed up
to the desired compression ratio.
This chamber can be highly cooled to lower the peak temperature
developed during the combustion process
To transfer the compressed air from the compression chamber to
the combustion chamber a third chamber - the pressure chamber
(PC = Pressure Chamber) – is necessary.
This chamber stores air under high pressure, which is the pressure
that air reaches at the end of the compression process.

Working Principle
9
Fig.3 The main moving part consisting of two pairs
of pistons (α & β), motion arm and engine shaft.
The engine comprises of two pairs of
symmetrically located pistons (each pair
consists of one CPC- and one CBC-piston).
The symmetrically located pairs of pistons
balance the engine, neutralizing oscillations
due to centrifugal and inertial forces.
The engine’s pistons rotate on different
rotation radius (RCPC & RCBC)
One or more motion arms transfer the motion
of the CBC-piston to the engine shaft which
subsequently moves the CPC-piston

Compared to most SI engines, where all processes take place within the same space but during different
strokes, in this engine, all processes occur simultaneously but in separate chambers.
There is an extra intermediate chamber (called pressure chamber) between the compression and
combustion chamber
This feature allows the independent optimization of each thermodynamic process (intake, compression,
combustion, expansion)
The generated symmetry and its inherent concentric operations eliminates the mechanical vibrations and
diminishes the sound effects
THE CONCENTRIC ROTARY ENGINE
10

WORKING
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Fig.4 Free Rotation Of CPC piston
Phase I: Free Rotation of the CPC Piston
Initially, the CPC piston (α) moves freely inside the inner
toroidal chamber (Figure 4).
The cylindrical pressure chamber (PC) is isolated from its
neighboring chambers and stores air under high pressure.
The pressure inside the PC depends on the pressure
developed inside the CPC at the end of the compression
process.

Contd..
12
Fig.5 Intake and Compression process
Phase II: Intake and Compression Process
All intake processes take place at the back side of the CPC piston and all
compression processes at the front side of the same piston (Figure 4).
All combustion-expansion processes take place at the back side of CBC-
piston and all exhaust removals at its front side.
When the CPC sliding port (γ) closes, the piston drags ambient air through
the intake port (δ) and fills the CPC while the piston is rotating.
At the same time, the compressed air is trapped between the CPC piston (α)
and CPC sliding Port (γ’).
The first sliding port allows for a successful intake process while the second
one enables the compression to take place respectively

Contd…
13
Fig.6: end of compression process.
Phase III: End of Compression Process
There is a moment, defined by the desired compression
ratio, when the compression process comes to its end and
then the pressure inside the CPC is equal to the pressure
inside the PC (Figure 6).

Contd…
14
Fig.7: communication of the chambers.
Phase IV: Air Transfer Process
All valves open and the communication of the PC with both other
chambers (CPC & CBC) is allowed (Figure 7).
Simultaneously, high-pressure air is forced to move from the PC to
the CBC.
When the high pressure volume VCPC + PC connects with the low-
pressure volume V CBC, a united volume VCPC + PC + CBC is formed.
At the same time, the injection process initiates. Fuel is injected
either inside the PC or the CBC.

Contd…
15
Fig.8: End of air transfer process - CBC
valve closes.
Phase V: End of Air Transfer Process (CBC Valve
Closes) Ignition and Combustion Process
The compressed air transfer continues until the pressure inside
the CBC volume comes to its highest value. At that point,
CBC-valve closes (Figure 8).
The high-pressure air-fuel mixture is ignited at the back side of
the CBC-piston, and the combustion process takes place.
Simultaneously, the front side of the same piston removes the
exhaust gases from the previous operation cycle through the
exhaust port (ε) to the environment (Figure 9).

Contd…
16
Fig. 9: End of high-pressure recovery
inside PC - CPC valve closes.
Phase VI: End of High-Pressure Recovery Inside
the Pc (CPC Valve Closes)
Once the pressure inside the pressure chamber becomes
equal to the pressure it was before the valves open, the
CPC-valve closes, and the CPC-sliding port opens to
allow the CPC piston to pass through (Figure 9)

Advantages of Designing a Concentric Rotary Engine
Apart from the main reason of avoiding extra components for translating the reciprocating motion to rotating,
there is also a secondary reason.
In reciprocating engines, the net force exerted on the shaft ends up being much smaller than the pressure force
applied to the piston.
The high pressure developed inside the combustion chamber (FK) applies a force on the piston that is much
greater than the force transferred to the engine shaft (FT).
On the other hand, the latter is the only force responsible for the engine’s torque generation. So, no matter how
great pressure force is developed inside the combustion engine, only a portion of that force (FT) is responsible
for the power production
A concentric rotary engine allows 100% of the pressure force applied to the piston to be transmitted
tangentially on the outer surface of the engine shaft, taking so full advantage of the pressure force that
generates power
Concentric Rotary Engine
17

The Wankel type engine is famous for its significantly higher power density than any other commercial
engine type. Each power stroke lasts 90o of the rotor’s rotation.
Since the driveshaft (output shaft) spins three revolutions for each revolution of the rotor, each power
stroke lasts through 270 o of the output shaft’s rotation
The SARM engine allows the production of a power stroke every 180o as it consists of two symmetrical
pistons responsible for each process. 9o are used for the air transfer from the PC and 11o for the CBC-
piston to pass and reveal the exhaust port. Thus, 160o out of 180o produce the engine’s mechanical work.
For all these reasons, the SARM engine is capable of reaching a higher power to weight ratio than any
other commercially available engine.
POWER DENSITY
18

THERMODYNAMIC CYCLE ANALYSIS
19

Higher efficiency, almost constant at the entire speed range, because of the existence of a pressure
chamber.
 Atkinson thermodynamic cycle (+20%).
 Fewer moving parts, resulting in lower friction losses.
Significantly lower weight (up to 6 times).
Greatly reduced volume (up to 5 times).
Few moving parts and thus oil usage as low as possible
Does not need a flywheel due its motion arm and pistons.
Industry
 Can replace existing IC engine applications
 Decreased engine volume allows the inspiration of new vehicle designs
Energy
 Low fuel consumption engines
Environment
 Better quality emissions
Advantages
20

The project is yet to be realized into practice
Complicated Valve and slide port timings
No cycle can be utilized in full potential and efficiency may not be as high as
calculated
Activity inside the pressure chamber cannot be controlled
Manufacturing and assembly is a complex process
The existing automotive designs would be changed and this poses a challenge
Disadvantages
21

Automotive
 Heavy duty engines
 Hybrid vehicles
Shipping
 Commercial and passenger ships
Aviation
 Large drones
 Small aircrafts
Energy
 Oil platforms
 Electricity production
Applications
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1. Savvakis, S., Gkoutzamanis, V., and Samaras, Z., "Description of a Novel Concentric Rotary Engine," SAE Technical Paper
(© 2018 SAE International); 2018-01-0365, 2018; doi:10.4271/2018-01-0365.
2. Spreitzer, J., Zahradnik, F., and Geringer, B., “Implementation of a Rotary Engine (Wankel Engine) in a CFD Simulation Tool
with Special Emphasis on Combustion and Flow Phenomena,” SAE Technical Paper (© 2015 SAE International) ;2015-01-
0382, 2015.
3. Zhang, L., Su, T., Zhang, Y., and Feng, Y., “Numerical Investigation of the Effects of Split Injection Strategies on Combustion
and Emission in an Opposed-Piston, Opposed Cylinder (OPOC) two-Stroke Diesel Engine,” Energies 10(5):684, May 2017.
4. F. Redon, C. Kalebjian, J. Kessler, N. Rakovec and et al., "Meeting Stringent 2025 Emissions and Fuel Efficiency
Regulations with an Opposed-Piston, Light-Duty Diesel Engine," SAE Technical Paper 2014-01-1187, 2014.
5. Ashley, S., “New Axial-Piston Engine Aimed at Range Extenders, Military Applications,” SAE Automotive Engineering, Aug.
2014.
6. A. Shkolnik, D. Littera, M. Nickerson, N. Shkolnik and et al., "Development of a Small Rotary SI/CI Combustion Engine,"
SAE Technical Paper 2014-32-0104, 2014.
7. V. G. Gkoutzamanis, S. Savvakis and A. I. Kalfas, “Numerical Simulation of a Novel Rotary Engine Compared to
Conventional Reciprocating Engine Cycle,” in GPPS Conference 2017, Shanghai, Oct 30 - Nov 1, 2017.
REFERENCES
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SARM Engine - A new concept of Concentric Rotary Engines

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