Energy Transfer (Kinetic to Pressure) Transducer
When an object with a kinetic energy charge hits another object, it imposes pressure. Independently of the nature of an object (Whether it is a steel balloon or a molecule), the nature of this pressure stays unchanged. Pressure is measured in pascals. Originally, it is a measure of force per unit area. 1 Pa = 1N / m2
The simplest transducer of such energy transfer is a spring that moves a needle along a scale. The more advanced transducers are piezoelectric. The main principle of these sensors is the measurement of an electric charge between two conductors. The distance between them is changed when the force which creates pressure is applied. (Al-Jazarí, 1973)
Heat Transfer
Heat transfer is the physical process of temperature transfer from a warmer body to a cooler one. The measurement principle is based on comparing the temperature flow of a sample and the tested material. The essence of a measuring process Is based on creating the thermal flow which heats a flat sample of a definite thickness, and which is directed perpendicular to the largest sizes of the sample. The power, which is needed for creating this thermal flow, temperature of the opposite sides of a sample, and the thickness of the sample define the heat transfer. Then, the heat transfer is calculated in accordance with the following formula.
P = power needed
H = thickness of the sample
∆T = the difference of temperatures
S = square of the sample
The measuring unit is W / (m*K). (Serway, Jewett, 2003)
Aerodynamic
Aerodynamic flow is defined by numerous factors, such as temperature, pressure (density), humidity and clearness of a gas. The speed of the flow may be defined in several ways. The most common is the measurement of the torque of a propeller that is rotated by the aerodynamic flow which moves the blades. Depending on the torque of the propeller, the aerodynamic speed is defined. Additionally, the optical method may be used, when the flow is colored with smoke, and the optical system measures the flow speed and direction of the smoke stream. This method is more complete, as it also helps to consider additional factors. (Stokes, 2002)
Flow-Type
Flow type measurements are performed by pneumatic primary transducers. They are built with the same principle, which is used for manometers and aerodynamic speed transducers. The gas stream velocity is analyzed with the special tube that takes the sample of a gas. Then, the flow type is compared with the test sample, and the flow type is defined. Hence, this type of measurement helps to define the contamination of the flow, speed, density and transparency. (Shkatov, Mironov, 1980)
Momentum Transfer
The measuring unit of momentum transfer measurement is kg * m / s
Hence, the main principle of the measurement gadgetry is to measure the power of the moment of the highest power. In mechanics, this may be achieved by fixing the highest value of the measurement and dividing it by the time of action. (Serway, Jewett, 2003) The measuring principle should inevitably consider the time of effect, otherwise, the value will be measured in Pa, which does not require considering the duration of the power applied. (Burstall, 1965)
Reference List
Al-Jazarí. 1973. The Book of Knowledge of Ingenious Mechanical Devices. Springer, 1973.
Burstall, Aubrey F. 1965. A History of Mechanical Engineering. The MIT Press.
Serway, R., Jewett, J. 2003. Physics for Scientists and Engineers (6 ed.). Brooks Cole.
Shkatov, E. F., Mironov, Yu. G. 1980 Flow-type instrument for measuring the dust content of gas streams. Translated from Izmeritel’naya Tekhnika, No. 10, pp. 32–33, 1980.
Stokes, G. 2002. On the Theories of the Internal Friction of Fluids in Motion. Transaction of the Cambridge Philosophical Society (8), 287-305.