Abstract
This paper presents the development and implementation of a novel robust sensing and measurement system that achieves fine granularity and permits new insights into operation of rotational machinery. Instant angle speed measurements offer a wealth of useful information for complex machines in which the motion is the result of multidimensional, internal, and external interactions. The implementation of the proposed system was conducted on an internal combustion engine. The internal combustion engine crankshaft’s angular velocity is the result of the integration of all variables of motor and resisting forces. The crankshaft angular velocity variation also reflects the interaction between the internal thermodynamic cycle of the engine and the plant it powers. To minimise the number of variables, we used for our experiments an aero piston engine for small air-vehicles—a well-made and reliable powerplant—connected to a propeller. This paper presents the need for a better sensing and measurement system. Then, we show the development of the system, the measurement protocol and process, recording and analysis of the data, and results of some experiments. We then demonstrate the possibilities this sensing suite can achieve—a deeper insight into the operation of the machine—by performing high-quality analyses of engine cycles, well beyond capabilities in the state of the art. This system can be generalised for other rotational machines and equipment.
Highlights
High-fidelity characterisation of operation of rotary machines has been conceptually straightforward but difficult to achieve in practice.The literature—detailed in Section 3—has demonstrated that a knowledge and technology gap has existed in successfully implementing instant angle speed (IAS) measurement systems for rotational equipment and engines
It is worth noting that the distancing of the detectors was not in opposition
The thermodynamic cycle in the internal combustion engine (ICE)’s combustion chamber drives the piston, connecting rod, crankshaft, and the power consumer—here, the propeller—at an angular velocity with a typical variation shown for one engine cycle (EC) in Figure 15
Summary
The time between each two-consecutive intersection ni points between the signal and the reference line is calculated, and the IAS can be computed. 3. Determine pulse-period Si (Table 1) of the counts difference between every point ni and precedent one ni− 1 , where the falling signal line intersects the reference line and record the delta values (Figure 12). Considering the case of a slow rotation with n near to 0 (Hz), the signal would rise on a vertical line at 180 ◦ e at pk = Sk /2. In this case, the signal tilting angle αk shows the offset of the middle point nk by ∆pk. An independent and separate tachometer speed check was performed for verification purpose
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