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This paper aims to characterize the acoustic field radiated by the piston transducer and measure a few parameters through the data visualization method.

Using the theoretical model of the ultrasonic transducer, the acoustic field data were acquired by scanning the ultrasound field of the piston transducer. And the visualized graphs of the ultrasonic data were displayed through 3D graphs including slice, iso‐surface and volume rendering, respectively. Furthermore, a few parameters of the transducer including beam width and spread angle were measured using the visualized data.

The visualized graphs of the acoustic field radiated by the piston transducer show that the data visualization method can expose obviously the space distribution of the ultrasound field and describe directly the cylindrical shape. And this method provides the basis of reliable measurement and assess for the ultrasonic transducer.

This paper presents a kind of measured method of the acoustic parameters using the visualized data. The measurement range has limitation.

This method is possible used in Medical ultrasonic.

This paper presents the visualized description of the acoustic field of the piston transducer and a measurement of two acoustic parameters using the visualized data.

This article aims to propose a new measurement method for ultrasonic power based on self-reciprocity theorem which turns the estimation of ultrasonic power to the measurement of first echo current and open-circuit voltage of the driving source.

The formula for ultrasonic power is derived which has corrected the position of pressure reflection coefficient on the interface of water and steel. The diffraction correction for focusing transducers is evaluated using numerical computation of the Rayleigh integral. One way to estimate the reflection coefficient of focusing beams on heterogeneous interface is also depicted.

Comparison experiment with radiation force balance method demonstrates that ultrasonic power measurement using self-reciprocity is sound in theory and feasible in practice.

It has a better capability of anti-environmental interference and, thus, can be extended to low-level and high-frequency power measurements.

A prototype gas prover was constructed to serve as the Italian primary standard for gas flow rates in the range 0.1 ml/min to 2 l/min. The new prover is used to calibrate high‐quality industrial standards, as well as the MFCs used in microelectronic fabrications and preparation of reference gas mixtures.Design/methodology/approach – The prover measures gas volume transfers caused by displacements of a 120 mm dia. motor‐operated piston, which is introduced into a temperature‐controlled chamber containing up to 3 l of the required working gas at near ambient conditions. Gas delivery is made at constant rate, whereas possibly variable incoming flows are measured at constant pressure. Displacements of the piston are measured by an optical interferometer.Findings – The analysis shows that standard uncertainty ranges between 0.013 and 0.03 percent. Owing to the very accurate control and measurement of both pressures and temperatures, these figures refer equally to volume and mass flowrate. Experimental comparisons with similar national standards at LNE‐France and NIST‐USA confirmed the consistency of measurement results in the three Nations.Research limitations/implications – The gas prover should be used with inert gases only.Practical implications – The national industrial gas standards and the best flow transducers can now be calibrated accurately down to unprecedented flowrate values.Originality/value – The need for measurement of extremely low gas flows is quite recent, therefore possibly less than ten primary national standards are available today worldwide. Several completely different principles and designs have been developed; description of design and performance of each instrument is important to assess their respective merits. The described apparatus is innovative as regards measurement range, accuracy and control techniques.

The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of the piston ring and liner. Mechanical properties of the piston ring, like ring stiffness, are also not altered. Effect of variation in bore on the movement of piston ring can be studied with the proposed technique.

The gap Hmin between the cylinder liner and the piston ring is formed due to the hydrodynamic pressure generated by the presence of oil film between piston ring and liner. This gap can be inferred by measuring the movement of the inner surface of piston ring with reference to a sensor mounted on the piston at a fixed distance from the piston ring. The piston ring is connected to the sensor through reasonably rigid member. The underlying assumption here is that there is no elastic deformation of the piston ring due to the hydrodynamic pressure. The fundamental sensor to measure oil film thickness used in this setup is a set of strain gauges.

It is possible to measure oil film thickness by the proposed arrangement for the entire stroke without changing the surface properties. Mechanical properties of the piston ring, like ring tension, are not affected. The results possibly provide the correct picture of the piston ring movement throughout the stroke. The measurement at near zero speed can give information on the movement of the piston ring due to hydrodynamic action and to the variation in the bore. The measurement is not affected by engine vibrations. The proposed technique can be helpful in validating the theoretical models proposed in the literature.

The measurement is possible only in unfired condition. However, this attempt can be considered as the basis to measure OFT in fired condition with necessary improvements. It is not feasible to measure quantity of lubricant/extent of lubricant on leading or trailing edge of piston. Effect of temperature on the oil film thickness cannot be studied as the engine is not fired. It is assumed that the piston ring does not pass through elasto‐hydrodynamic lubrication regime. Debris/worn out particles in the oil may affect the indicated oil film thickness at local points.

Engine friction will continue to affect the efficiency of vehicle power plants as long as we have vehicles that use their own prime movers. A consequence of this, of course, is the fact that the truly “adiabatic” power plant needs rather more than an insulated combustion chamber. What is not so certain is the extent to which engine friction could be reduced and whether that reduction when achieved is worth all the effort.

An engine test rig has been designed and built for evaluation of monolithic ceramic components and metal components protected by ceramic shields or coatings for operation in the high temperature environment of the combustion gases of an uncooled diesel engine. Tests on the first monolithic ceramic components have shown thermal shock capability to be more critical than resistance to tensile bending, or vibration induced stresses. Configuration design can reduce the effects of the latter more readily than it can deal with thermal shock.

This paper aims to carry out a thermal-hydraulic simulation model for pump and hydraulic system to predict the temperature increasing and pump performance. Based on the model, how to alleviate the temperature is introduced. Besides, the optimization of piston is carried out.

This paper analyzes the heat generation in lubricating interfaces of the pump with energy conversion theory. The heat transfer inside the pump is analyzed with the control volume method. The simulation model is constructed in AMESim because of its operating friendly nature. The experiment is carried out to prove the validity and accuracy of the simulation model.

Temperature has less effect on the mechanical loss of pump. However, it has a great impact on volumetric efficiency. To reduce the temperature on the piston surface, the size of the piston should be optimized.

This paper fulfills a novel thermal-hydraulic model to evaluate the temperature of the pump. Based on the model, the performance of the pump is determined and optimization is carried out.

This paper describes a free‐piston driven expansion tube and its instrumentation. The facility is used to generate rarefied flows at speeds of approximately 10 km/s. Although the flow in the tube itself is in the continuum regime, rarefied flow conditions are achieved by allowing the test gas to further expand as a free jet into the facility's test section. The test flow is surveyed to provide bar‐gauge pressure measurements. Numerical simulation is then used to describe more fully the test flow properties. The flows produced are suitable for the aerodynamic testing of small models at superorbital speeds and should provide data that are suitable for the calibration of Direct Simulation Monte‐Carlo codes.

The purpose of this paper is to investigate, theoretically and experimentally, the sealing performance of the axial piston seal on a larger diameter (100 mm in diameter) axial piston and reveal the sealing mechanism of the axial piston.

Based on the characteristics of the clearance flow between the seal and the piston, reasonable boundary conditions for Navier‐Stokes' equations are determined and the equations are modified, so that the final equations can describe the real flow state of the clearance flow.

Through combining the final equations with finite element method, the pressure distributions within the clearance field for the sealing part during the reciprocating motion of the piston and the leakage rate with the pressure are obtained. The deflections of the sealing part which affect sealing performance have been given.

Theoretical and experimental results show the internal relationship between the seal and the piston, also help to develop some newer piston pumps and improve on the seals of present high‐pressure piston pumps.

The purpose of this paper is to present a measurement technique wherein the film thickness is measured in unfired condition for entire stroke length but without impairing the original condition of piston ring, liner and lubricant, i.e. non-invasively. Film thickness is measured at different speeds up to 500 rpm. The measurements are initially carried out at near zero speed followed by speeds mentioned above. Measurement highlights the combined effect of variation of bore diameter and ring face profile on the film thickness.

The film thickness is measured with the help of a set of strain gauges. Four strain gauges are mounted on a sufficiently elastic steel strip which is mounted in a simply supported condition. This assembly of strain gauge is mounted on small rectangular bracket. A cutout is made in the piston to accommodate the bracket. A pin bearing a slot of size sufficient enough to accommodate the piston ring on one side is fixed between the piston ring and the strain gauge assembly. This ensures the transfer of the movement of the piston ring on to the strain gauge. The deflection of the strain gauge is pre-calibrated against a sufficiently accurate dial gauge. Hence any radial movement of the piston ring is sensed by the strain gauge assembly. A data logger unit is connected to the strain gauge output to log the data at every crank angle. A rotary encoder is connected to the crank shaft, to have the correlation of the strain gauge output with the crank angle.

The technique is capable of measuring oil film thickness for entire stroke at low speeds in unfired engines. The effect of variation in bore diameter on the oil film thickness is significant and hence such measurement can enlighten the path for research to reduce friction. The experimental results of the oil film thickness are in good agreement with predicted values, particularly in the forward stroke (BDC to TDC).

The methodology is not suitable for fired engines as on date but can be taken up as a future work with necessary modifications. It does not take into consideration the effect of elasto-hydrodynamic lubrication.

It can be used to measure OFT between piston ring and liner in unfired engines and reciprocating compressors also.

It can help to indentify the areas of research so that the friction between piston ring and liner can be reduced thus increasing efficiency of the engine and reducing fuel consumption and emissions.

The work presented is a part of PhD work under progress at S V National Institute of Technology, Surat, India. The setup is in the college premises and the experiments are conducted on the same.