Measurement of pulsating temperature and velocity in an internal combustion engine using an ultrasonic flowmeter

Invited review article: Unsteady and pulsating pressure and temperature: a review of experimental techniques.

Abstract: Unsteady flow of liquids and gasses are important in many scientific, engineering, and biological contexts. Measurement of the characteristics of unsteady and pulsating flows is more difficult than that of static flows. Time constants of the sensors must be understood, sampling rates must satisfy basic signal processing criteria and synchronization of the measurements with the flow may be necessary. Because of development of more advanced measurement devices, there has recently been a growing interest in unsteady and pulsating flow measurements and the number of papers in this field has increased in recent years. This paper reviews the current state of the art in sensors and measurement techniques for the characterization of pressure and temperature in unsteady and pulsating flows including an analysis of the advantages and limitations of each technique.

Simultaneous measurements of dynamic values using the transit time method

Abstract: The problem of simultaneous and accurate measurements of two dynamic values, time dependencies of flow velocity and ultrasound velocity in the flow, is analyzed. In order to measure two dynamic values simultaneously a theory of the transit time method has developed, and the theoretical model of a microprocessor-based measuring system has been derived. The ways to improve the accuracy and information of such dual-channel measurement systems have been examined. It is shown that invariance between two channels of a measurement system can be achieved when dynamic, nonlinear, parametric models of these channels are identified in real time during the process of measurement, and when the multipulse irradiation of flow is used. The results of computer simulation of transit time method dynamic errors are represented. A method of minimizing these errors has been proposed. >

Hydrocarbon Emissions from Spark Ignition Engines

Abstract: To contrast the phenomenon of HC formation in a Diesel and a spark ignition engine, a chapter is included on the latter. The absorption and desorption of fuel by cylinder lubricating oil films has been modelled using principles of mass transfer in this Chapter. Henry’s Law for a dilute solution of fuel in oil is used to relate gas to liquid phase fuel concentrations. Mass transfer conductances in gas and liquid phases are considered, the former via use of Reynolds’s Analogy to engine heat transfer data, the latter through assuming molecular diffusion through an effective penetration depth of the oil film. Oxidation of desorbed fuel is assumed complete if the mean of burned gas and lubricating oil film temperatures is greater than 100 K. Below this value, the desorbed fuel is considered to contribute to hydrocarbon emissions. Comparison with engine test data corroborates the absorption/desorption hypothesis. The model indicates the equal importance of gas and liquid phase conductance.

Method and arrangement for the detection of misfire of internal combustion engines

Abstract: A method and system are provided with which it is possible to detect non-firing and untimely firing events in internal combustion and, if necessary, the temperature of the gas in the exhaust gas pipe. This is performed in general by measuring the speed of sound and determining the phase angle between the sender and receiver either arranged on different sides of the exhaust gas pipe or on the same side of the exhaust gas pipe. The receiver, depending on the measurement principle, can include one, two, or in special applications three receivers. Additionally, if necessary, it is possible to suppress the structure-borne sound influence on a speed of sound measurement with low cost and high stability.

Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

Abstract: Energy carried by engine exhaust pulses is critical to the performance of a turbine or any other exhaust energy recovery system. Enthalpy and exergy are commonly used concepts to describe the energy transport by the flow based on the first and second laws of thermodynamics. However, in order to investigate the crank-angle-resolved exhaust flow enthalpy and exergy, the significance of the flow parameters (pressure, velocity, and temperature) and their demand for high resolution need to be ascertained. In this study, local and global sensitivity analyses were performed on a one-dimensional (1D) heavy-duty diesel engine model to quantify the significance of each flow parameter in the determination of exhaust enthalpy and exergy. The effects of parameter sweeps were analyzed by local sensitivity, and Sobol indices from the global sensitivity showed the correlations between each flow parameter and the computed enthalpy and exergy. The analysis indicated that when considering the specific enthalpy and exergy, flow temperature is the dominant parameter and requires high resolution of the temperature pulse. It was found that a 5% sweep over the temperature pulse leads to maximum deviations of 31% and 27% when resolving the crank angle-based specific enthalpy and specific exergy, respectively. However, when considering the total enthalpy and exergy rates, flow velocity is the most significant parameter, requiring high resolution with a maximum deviation of 23% for the enthalpy rate and 12% for the exergy rate over a 5% sweep of the flow velocity pulse. This study will help to quantify and prioritize fast measurements of pulsating flow parameters in the context of turbocharger turbine inlet flow enthalpy and exergy analysis.

Measurement of -- Gas Temperature in an Engine by the VELOCITY OF SOUND METHOD

Abstract: THIS paper outlines a new method of measuring end-gas temperatures within the cylinder of an operating engine. The new instrument measures the acoustical properties by the pulse method, transmitting an acoustical impulse through a gas path of known length and measuring the time of propagation through the gas. The method yields a value for the average velocity of sound in the path. The authors describe the instrument and engine modifications necessary. The results of tests are also discussed, with a detailed description of one series. The appendixes outline the mathematical steps of finding the sound velocity in gas mixtures and the fuel-air cycle for the detailed series of tests.

Simulation and Evaluation of a 4-Stroke Single-Cylinder Spark Ignition Engine

Abstract: This paper deals with the development and evaluation of a mathematical model for a 4-stroke, single-cylinder, spark ignition engine. The first part describes the development of the mathematical model and the computer program. The assumptions that were made in the model are also described. The instruments that were developed for the evaluation of the model are included in the second part, which also contains the evaluation of the results obtained from the model. /GMRL/

A Sonic Velometer

Abstract: Wind-velocity measurement at remote winter mountain sites is hampered by icing of the moving parts of the measuring device and by restrictions on the amount of electrical power which is available. A sonic velometer which determines the wind velocity by measuring the transit times of sound pulses in air and has no moving parts has been developed. The sound pulse transit times are measured accurately through the use of phase-locking techniques. Circuit construction is exclusively solid state, with integrated circuits used for several functions. The device exhibits an uncertainty of 0.05 percent in the determination of the pulse-transit times yielding a wind-velocity resolution capability of 0.13 m/s. The velometer has been tested over a dynamic range of 5 m/s.