298
A. A. Kadam et al.
Hence, studies related to combustion phenomena still attract the interest of many
combustion engineers for meeting the twenty-first-century society needs.
The challenge posed by modern society in terms of curtailing the effect of global
warming is critical and is of paramount interest. Therefore, better quality of life is
at a crux of combustion. In reality, combustion is an everyday business with wide
variety of applications ranging from usage of firewood to powering the space ships.
Combustion as a process proceeds with a small kernel formation and grows up to
a matured flame front through unburnt charge. Furthermore, nature of flame front
may initially begin as laminar and then progress to turbulent phase depending on
the prevailing conditions, as generally witnessed in fire hazard cases. Therefore,
studies related to effects of combustion process (flame stabilization, lift-off, blow-off,
auto-ignition, etc.) are significant.
The combustion properties such as flame speed, ignition delay, minimum ignition
energy, and the flammability limits [1–3] are greatly influenced by mixture strength,
pressure, and temperature. Among these, laminar flame speed is significant, which
strongly affects the burn rate and thus a critical property in the design of combustors
[3]. Furthermore, laminar flame speed possesses inherent details such as diffusivity
and reactivity of mixture involved [4], and the laminar flame speed data is also used
in validation of chemical reaction mechanisms [5]. Various methods of measuring
flame velocity are flat flame burner, slot burner, constant volume bomb method,
constant pressure bomb method, tube methods, and so on [6]. For the present work,
tube method was considered because of its simplicity for the purpose of burn rate
model studies at the Combustion Research Laboratory of Jain College of Engineering,
Belagavi.
Major advantage of the tube method is that the effect of the surrounding atmosphere due to diffusion is not present as in case of burner method. Also, the quantity
of fuel required is small as compared to the burner system. To minimize the effect
of convection, a horizontal tube is used instead of a vertical one. On the other hand,
the cylindrical tube method possesses few problems such as parallax error of human
eye, quenching effect along the walls of tube, a hook shaped flame front along the
axis, and distorted flame front due to reflected pressure waves which are well known
issues. In the following section, the details of automation on in-house developed
flame tube along with measurement of flame speed considering LPG–air mixtures
are discussed.
2 Experimental Setup
Flame propagation as a subject needs sophisticated modern measurement system due
to the sensitivity in handling time intervals and flame front studies; this constitutes
a major challenge while studying this subject. Transparent glass tube made up of
borosilicate glass of 3 m length and 0.025 m of internal diameter was considered.
The entire test-rig was designed based on the dimensions of the flame tube. The
A. A. Kadam et al.
Hence, studies related to combustion phenomena still attract the interest of many
combustion engineers for meeting the twenty-first-century society needs.
The challenge posed by modern society in terms of curtailing the effect of global
warming is critical and is of paramount interest. Therefore, better quality of life is
at a crux of combustion. In reality, combustion is an everyday business with wide
variety of applications ranging from usage of firewood to powering the space ships.
Combustion as a process proceeds with a small kernel formation and grows up to
a matured flame front through unburnt charge. Furthermore, nature of flame front
may initially begin as laminar and then progress to turbulent phase depending on
the prevailing conditions, as generally witnessed in fire hazard cases. Therefore,
studies related to effects of combustion process (flame stabilization, lift-off, blow-off,
auto-ignition, etc.) are significant.
The combustion properties such as flame speed, ignition delay, minimum ignition
energy, and the flammability limits [1–3] are greatly influenced by mixture strength,
pressure, and temperature. Among these, laminar flame speed is significant, which
strongly affects the burn rate and thus a critical property in the design of combustors
[3]. Furthermore, laminar flame speed possesses inherent details such as diffusivity
and reactivity of mixture involved [4], and the laminar flame speed data is also used
in validation of chemical reaction mechanisms [5]. Various methods of measuring
flame velocity are flat flame burner, slot burner, constant volume bomb method,
constant pressure bomb method, tube methods, and so on [6]. For the present work,
tube method was considered because of its simplicity for the purpose of burn rate
model studies at the Combustion Research Laboratory of Jain College of Engineering,
Belagavi.
Major advantage of the tube method is that the effect of the surrounding atmosphere due to diffusion is not present as in case of burner method. Also, the quantity
of fuel required is small as compared to the burner system. To minimize the effect
of convection, a horizontal tube is used instead of a vertical one. On the other hand,
the cylindrical tube method possesses few problems such as parallax error of human
eye, quenching effect along the walls of tube, a hook shaped flame front along the
axis, and distorted flame front due to reflected pressure waves which are well known
issues. In the following section, the details of automation on in-house developed
flame tube along with measurement of flame speed considering LPG–air mixtures
are discussed.
2 Experimental Setup
Flame propagation as a subject needs sophisticated modern measurement system due
to the sensitivity in handling time intervals and flame front studies; this constitutes
a major challenge while studying this subject. Transparent glass tube made up of
borosilicate glass of 3 m length and 0.025 m of internal diameter was considered.
The entire test-rig was designed based on the dimensions of the flame tube. The