Reciprocating engines work similarly to the engines found in most cars, but they have been modified to include features like dual ignition systems for safety and redundancy, and air cooling to reduce weight.
To improve performance, turbochargers and, less frequently, superchargers can be added to aircraft piston engines. Typically, aircraft piston engines are fueled with AVGAS, but diesel-fueled engines are becoming more prevalent, particularly in light aircraft.
In this article, we will explore what a reciprocating engine is, it’s application, diagram, types, and how it works.
What Is Reciprocating Engine?
Reciprocal engines, also known as piston engines, are usually heat engines, but they may also be pneumatic or hydraulic. They work by using one or more reciprocating pistons to transform pressure into rotation.
Often called a reciprocating engine or “recip,” an aircraft piston engine is an internal combustion engine that uses one or more reciprocating pistons to convert pressure into a rotational motion.
One or more pistons are used in a reciprocating engine to transform pressure into rotational motion. This energy is converted by means of the pistons’ reciprocating (up-and-down) action.
Internal combustion engines, which are found in the majority of automobiles, external combustion engines, such as steam engines, and Stirling engines are just a few of the many varieties.
The triangular rotor of a rotary engine would allow it to perform the same function as a reciprocating engine, but in a totally different way.
One can further categorize internal combustion engines into two types: compression-ignition (CI) engines, in which the compressed air inside the cylinder heats up and ignites the fuel injected at that time or earlier, or spark-ignition (SI) engines, in which the combustion is started by the spark plug.
Apllications
- Combustion engines are crucial in the oil and gas industry for power plants, compression, and pumping.
- Power plants use engines to burn unsuitable fuel for turbines.
- Pumping systems provide mechanical drive.
- Compression moves natural gas through distribution lines.
- Reciprocating engines are widely used due to their high efficiency, flexibility, and reliability.
- Understanding reciprocating engines, their advantages, and maintenance requirements is essential.
Diagrams
Types Of Reciprocating Engine
Below are the various types of reciprocating engines:
Radial Engines:
A central crankcase is surrounded by a row, or rows, of cylinders that make up a radial engine. This kind of engine has shown itself to be very reliable and resilient. There might be three, five, seven, or nine cylinders in a row.
Two rows of seven or nine cylinders, one in front of the other, are radially placed around the crankcase in some radial engines. We refer to them as double-row radials. There are four rows of cylinders in one kind of radial engine, with seven cylinders in each row, for a total of 28 cylinders.
Some antique crop spray aircraft, warbirds, and freight planes still employ radial engines. There are still a lot of these engines in operation, although they are not very common.
With a two-section main crankcase and a one-piece nose, the single-row, nine-cylinder radial engine is comparatively straightforward in design. Compared to single-row engines, the bigger twin-row engines have a significantly more complicated structure.
The front portion of the Wright R-3350 engine, the four major components of the crankcase, the rear cam and tappet housing, the supercharger front housing, the supercharger rear housing, and the supercharger rear housing cover, for instance, make up the crankcase.
Despite significant differences in construction and nomenclature, Pratt & Whitney engines of similar size have the same fundamental parts.
Opposed or O-Type Engines:
With a crankshaft in the middle, the opposed-type engine has two banks of cylinders positioned straight across from one another. The single crankshaft is attached to the pistons of both cylinder banks.
The engine is mostly used in aviation, even though it may be either liquid-cooled or air-cooled. The cylinders are often positioned horizontally when it is installed.
The opposed-type engine is perfect for horizontal placement on the aircraft wings (twin-engine applications) due to its thin profile and low weight-to-horsepower ratio. Its low vibration properties are an additional benefit.
Inline Engines:
An inline engine typically has an even number of cylinders, though some three-cylinder engines have been built. They can be either liquid-cooled or air-cooled, and they have a single crankshaft that is either above or below the cylinders.
An inverted engine is one that is built to operate with the cylinders inverted, which offers the benefits of shorter landing gear and better visibility for the pilot.
As the engine size increases, the air-cooled, inline type presents additional challenges to provide adequate cooling, so this type of engine is limited to low- and medium-horsepower engines found in very old light aircraft.
V-Type Engines:
V-Type Engines V-type engines are characterized by a V followed by a dash and the piston displacement in cubic inches. The engines are used primarily in older aircraft and were used primarily during World War II.
For instance, V-1710 has 12 cylinders that are either liquid-cooled or air-cooled and are designated by a V followed by a dash and the piston displacement in cubic inches.
Rotary Engines:
During World War I, rotary piston engines were created for use in military aircraft. This design generates more airflow for cooling since the whole engine revolves with the propeller.
How Does A Reciprocating Engine Work?
Reciprocating engines work by producing mechanical energy from the heat and pressure that are created when fuel and air are burned. An engine that employs one or more pistons to transform pressure into rotational motion is known as a reciprocating engine.
They convert this energy using the pistons’ reciprocating (up-and-down) action. One row of cylinders (in-line), two rows convergent to a single point (V-engine), a double zigzag (W-engine), and two horizontal rows (opposed engine) are common engine block layouts.
The general case will be examined since the three engines—internal combustion, steam, and Stirling—all use slightly different procedures to finish the cycle.
- Intake: A fuel mixture enters the cylinder via the intake port to start the cycle, which causes the piston to expand to the cylinder’s bottom.
- Compression: The fuel mixture is compressed and ignited by the spark plug once the piston is forced to the top.
- Ignition: The ignition forces the piston downward, giving the engine productive activity.
- Exhaust: The cycle is repeated once the waste chemicals are released via the exhaust port.
The engine gets its energy from the four-stroke cycle, but it now has to convert that energy into rotational energy for the wheels, driveshaft, and gearbox. The crankshaft does this.
In order to preserve the discontinuous reciprocating energy as rotating energy, the crankshaft transforms this up-and-down action into rotational motion, which is often coupled with a flywheel.
FAQs
What is the difference between a reciprocating engine and a combustion engine?
A reciprocating engine, often known as a piston engine, is one of two kinds of combustion engines that use fuel to produce energy. Reciprocal engines are more prevalent, although rotary engines, an older form, are still in use today.
What is a reciprocating engine also known as?
Aircraft piston engines, often known as reciprocating engines or “recip” engines, are internal combustion engines that employ one or more reciprocating pistons to transmit rotational motion in response to pressure.
What is the difference between a reciprocating engine and a rotary engine?
In addition to using a different process to complete the four-stroke cycle, rotary engines vary from the more popular reciprocating engines in a number of ways. Reduced moving parts: Ordinary reciprocating engines contain at least 40 moving parts, but a two-rotor rotary engine has just three: two rotors and an output shaft.
What are the two types of reciprocating engines?
The fundamental idea behind reciprocating engines is the transformation of chemical energy, or fuel, into mechanical energy. Through the process of combustion, this conversion takes place within the engine’s cylinders. Spark ignition and compression ignition are the two main types of reciprocating engines.
What are the 4 main strokes of a reciprocating engine?
- Intake: Also known as induction or suction.
- Compression: Starts at B.D.C., ends at T.D.C.
- Combustion: Also known as power or ignition.
- Exhaust: Also known as outlet.