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The reciprocating piston petrol engine
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
For convenience of expression the opening and closing points of the valves have traditionally been shown in the form of a valve timing diagram (Figure1.121c), although the trend in present-day service manuals is merely to tabulate this data, or simply to quote the number of degrees before top dead centre when the inlet valve begins to open. For tabulating valve timing information the commonly used abbreviations BTDC and ATDC denote before top dead centre and after top dead centre, and refer to the positions of the crankshaft as the piston is respectively advancing towards, and retreating from, the combustion chamber. Similarly, BBDC and ABDC denote before bottom dead centre and after bottom dead centre, and correspondingly relate to the opposite sense of piston travel.
Work and energy
Published in J.N. Fawcett, J.S. Burdess, Basic Mechanics with Engineering Applications, 2012
Suppose that the drive torque acting on the flywheel due to the action of the drive motor is constant and has a value MO. Let the rotation of the crank, and hence that of the flywheel, be defined by the angle θ from the vertical corresponding to the upper extreme or top dead centre (TDC) position, as shown by the line diagram of the crank-slider mechanism in Fig. 5.52.
Geometry and trigonometry
Published in Allan Bonnick, Automotive Science and Mathematics, 2008
As a result of wear, the timing marks on an engine flywheel have been lost and it has become necessary to reinstate them. The top dead centre position has been determined and the rim of the flywheel marked accordingly. The task is to place a mark on the flywheel rim that indicates 15 before TDC.
The effect of vibration on kinematics and muscle activation during cycling
Published in Journal of Sports Sciences, 2022
Josef Viellehner, Wolfgang Potthast
Where lowEMG indicates the level of activation in the less active muscle and highEMG is the level of activation in the more active muscle. This ratio was multiplied by the sum of the activation detected in both muscles. This method accounts for the magnitude and timing of antagonistic muscle activation. EMG and kinematic data was normalized to the 360° crank cycle based on the pedal axis movement. The crank axis’s highest point marks the top dead centre (TDC) of the crank cycle, 180° crank angle mark the bottom dead centre (BDC). Functionally the phases of the crank-cycle separate into downstroke (30° – 150°), bottom of stroke (150° – 210°), upstroke (210° – 330°), and top of stroke (330° – 30°; Dorel et al., 2008; Figure 1). In addition to the time series, discrete values for mean activation and mean co-contraction over the entire crank cycle were calculated (Table 2, appendix).
Combustion, performance, vibration and noise characteristics of cottonseed methyl ester–diesel blends fuelled engine
Published in Biofuels, 2022
The tests were performed at 210 bar injection pressure and for 4 different loads (2.5, 5, 7.5 and 10 Nm). The engine speed was adjusted to 1500 rpm, and then gas spindle was held constant at this speed during all experiments. The exhaust gas temperature was measured by the aid of a NiCr/Ni thermocouple, an accuracy of 1 °C. A kübler sendix model encoder with an accuracy of 0.1° was attached to the crankshaft in order to measure the top dead centre (TDC), crank angle, and engine speed. Before starting the experiments, the test engine was run until approximately 5 minutes and the measurements were obtained after the stable data flow was obtained. The measured values were repeated five times under the same test conditions and then the arithmetic averages of these five measurements were calculated for each given value. A Febris combustion analysis software to collect the data and to analyse the combustion process was used in the study. Combustion data were processed by an Optrand Auto PSI-TC pressure sensor with a precision of 1% in the combustion chamber during all experiments. Depending on the crank angle (°CA), the heat release rate was determined by the start and finish of the combustion. All the data were obtained by taking an average of 500 cycles. This software calculated the heat release rate using the formula in Eq. (1) in accordance with the first law of thermodynamics.
Start of injection timing effect on performance and exhaust emissions of a combustion engine powered by a diesel-oleic acid methyl ester biodiesel blend
Published in International Journal of Ambient Energy, 2023
Ahmed Ketata, Olfa Moussa, Zied Driss
In the first part, the numerical one-dimensional (1-D) model has been validated with test data for six blends of diesel and oleic methyl ester biodiesel. The considered volume fraction percentages of the biodiesel in the blends are of 0%, 20%, 40%, 60%, 80% and 100%, denoted as B0, B20, B40, B60, B80 and B100. In the second part, the B20 blend has been chosen for studying the effect of the start of injection timing on the performance, flow characteristics and exhaust emissions of the engine. Six starts of injection timings are −40°, −30°, −20°, −10°, −5° and 0°. These angles are relatives to the top dead centre crank angle of the engine. It is worth mentioning that the crankshaft angle of 0° matches the top dead centre of the cylinder.