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We studied the effect of steering dynamics on lateral dynamics for a 1.6 ton 4x4 sport utility vehicle (SUV) on deformable surfaces. The vehicle used for the outdoor tests was equipped with (1) a steering robot to apply repeatable steering wheel excitations and (2) a high-precision differential GPS (DGPS) system to gather physical measures that describe lateral dynamics: lateral acceleration, yaw rate, and vehicle sideslip angle. The vehicle was driven over three different deformable surfaces~a loess and a sandy soil and wet snow~with a constant speed of 10 km/h. The steering robot applied inputs of (1) sine wave excitation at 0.5, 1.0, and 2.5 Hz, and (2) ramp change (or trapezoidal) excitation with steering wheel rate at 100, 500, and 1500 deg/s. Results are presented as frequency paths and time courses to analyze effects of surface and steering dynamics.

The paper contains experimental results of soil stress state under loading of commercial wheeled vehicles. The measurements were performed with the use of SSTs (Stress State Transducers), which enable to determine soil pressures needed for calculations of stress state at a point: principal stresses and their direction cosines as well as octahedral stresses. A detailed description of the measuring method with an introductory theory of operation of the SST together with some methodology aspects of soil pressure measurements are included. The field tests were conducted on three different soil surfaces: loess, sand and turf as well as on snow surface in winter conditions. For the tests, two vehicles were used: a 5,6T 4x4 truck and a 14T 6x6 truck. The vehicles were driven at constant low speed or at different speeds. Moreover, effects of wheel loading, reduced inflation pressure, drive modes (rolling or driving) were also analyzed.

The ignition method significantly affects the combustion process in piston aircraft engines. This paper presents the results of bench tests of two variants of the radial piston aircraft engine: equipped with a standard magneto system and an electronic dual ignition system. The engine was tested in steady states for operating points defined by rotational speed and load. Their values corresponded to a load ranging from 50% of nominal power to take-off power. The ignition advance angle was constant for the engine equipped with ignition magnetos, while for the second engine variant it was determined by the developed algorithm introduced to the electronic ignition system control unit. The analysis of the combustion process was based on pressure measurements in one cylinder.

The paper presents the results of the analysis of the simulation tests of the flow of fuel through the fuel rail for the designed radial aircraft engine. A 3D model has been developed for CFD calculations including the fuel rail and elements supplying the fuel to the injectors. Simulation tests were carried out using Star-CD software. The objective of simulation tests has been to determine flow characteristics of the fuel rail design. This design is atypical due to: the shape of the rail - a torus with internal diameter 630 mm, and the fuel flow rate of approximately 30 l/min. Analysis covered flow velocity and pressure at selected points of the design. The tests were conducted for two cases. The first covered constant fuel flow from all injectors; the second covered dynamic states that take place when the injector is opened. The purpose of these tests was to check the possibility of using this solution for prototype purposes.

The paper presents the results of analysis of radial piston carburettor engine operation irregularities. The analysis covers indicated pressure and maximum pressure and the angle of its occurrence. Both the values of these parameters at different points of operation of this engine and individual differentiation of individual cylinders in the given points are shown.

The paper presents a simple method of analyzing and modeling the cycle-to-cycle variation of engine work. The method is based on the dependence between parameters of consecutive cycles. The author proposes applying an additional forgetting factor that defines to what extent the previous state of the object (i.e. the analyzed or modeled value) affects its present state. The paper outlines a method of determining this factor's value on the basis of signal analysis. A method of modeling a process of any configuration of three parameters: mean value, standard deviation and forgetting factor is described. Finally, the paper presents the results of cycle-to-cycle analysis of mean effective pressure variation in the function of spark advance of the IC engine working in idle speed. A method of interpreting the results is proposed, allowing for symmetry of the process analysis: forward and back in time.

In this paper a model of the wheel-soil system and its identification are presented. The model assumes the interaction between a wheel and soil can be described by the soil stress state under wheel loads. The stress state can be defined by means of the major stresses and their direction cosines, as well as the stresses in the octahedral stress system. Based on the soil stress analysis, traction forces in the wheel-soil system can be obtained by integrating the stresses. Identification of the model was performed using a 5T 4×4military truck, which was driven over three different soil surfaces and over a snow surface. For the identification of the model, values of drawbar pull force as well as soil stresses and deformation were required and they were measured in field experiments.

The fluctuations in the combustion process of diesel fuel with hydrogen addition in an internal compression ignition engine were investigated. The cyclic combustion pressure was measured and its cyclic oscillations were expressed by indicated mean effective pressure per cycle. The statistical and multifractal analyses applied to the corresponding time series showed considerable changes in the engine dynamics for hydrogen percentages ranging from 5% to 20%. The study for the diesel engine was carried out for 11 various operating points and at the speeds ranging from 1200 to 2000 rpm. Also, exhaust gas components were analyzed. The hydrogen addition was found to affect the differentiation of the indicated mean effective pressure in the engine. A reduction of CO₂ emissions and an increase in NOx emissions were registered.

The paper presents the results of experiments on the effects of supply pressure and supply voltage on the pulse gas injector opening time. Two characteristics have been investigated into: the opening lag time and the time of opening. The injector's opening lag was defined as the time between the occurrence of a control signal and the moment of the valve's starting to move. The injector's time of opening was defined as the time of the valve element's movement from the closed to the fully open position. The analysis covered 6 injector types differing in the design of the valve element and the coil. The injectors types were representative of designs most popular in the market: piston and plate injectors calibrated by means of the piston stroke or the outlet diameter. The experiments were conducted in a bespoke test bed, and compressed air was used in lieu of gas fuel.

Ammonia, which is one of the most produced inorganic chemicals worldwide, has gained significant attention in recent years as a carbon-free fuel due to its significant energy density in maritime and power plant applications. This fuel offers several advantages including low production costs and being safe for storage and transport. Reactivity controlled compression ignition (RCCI) combustion mode is considered as a promising strategy reducing the level of nitrogen oxides (NOx) emissions and particulate matters (PM) in internal combustion engines (ICEs) due to the lower combustion temperatures and charge homogeneity. Ammonia-based RCCI combustion strategy can offer a simultaneous reduction of CO2 and NOx. In this study, a RCCI engine fuelled by ammonia and diesel is numerically simulated considering chemical reactions kinetics mechanism of the combustion.

The paper considers the effect of axial and radial clearances of compression rings in the piston grooves on the engine blowby. A mathematical model of piston-rings-cylinder seal, which integrates model of gas flow through the crevices of the RPC seal and model of rings motions in the grooves was used to predict the influence of particular clearances values on the blowby. The results of numerical calculations show that this influence is different for the top and second ring clearances and depends on engine operating conditions (especially rotational speed). The paper also presents some results of experimental research conducted to verify the model. The results of the experiment confirmed the results of the numerical predictions.