This paper investigates the effect of separated exhaust expansion chamber parameters on pressure oscillations in spark-ignited internal combustion (IC) gasoline engines. It is known that exhaust expansion chambers are becoming increasingly more popular among both – original equipment (OE) and aftermarket equipment (AE) exhaust system manufacturers for performance-oriented motorcycles equipped with mainly single cylinder engines, but the companies are reluctant to reveal any detailed principles of operation of the mentioned expansion chambers. The subject of this research is the type of expansion chamber (separate) as used on performance-oriented motorcycles, particularly its’ effect on exhaust pressure pulsations as different chamber volumes, locations and passage sizes are tested. Time-dependent computational fluid dynamics (CFD) analysis was carried out in Solidworks Flow Simulation environment on a simplified exhaust header pipe model imitating engine operation at full load and steady speed. Honda CRF450R motorcycle engine was used as the example and fully defined using a 1D engine performance calculator software to determine the combustion chamber pressure and exhaust valve lift at any given crankshaft position. Volume flow rate of exhaust gasses at the header pipe inlet was calculated based on engine parameters and operating speed. The average pressure values with respect to physical time were measured and graphed across the header pipe inlet cross-section. Eight different header pipe and exhaust expansion chamber combinations were modelled, tested, and results compared at low, medium and high engine speeds. It was found that the presence of exhaust expansion chamber tends to dampen the amplitude and decrease the frequency of pressure oscillations generated at the opening of the exhaust valve(s). Observations show that the addition of an expansion chamber as per design of performance-oriented motorcycles helps to decrease the negative effect of engine tuning while also dampening the positive effect.

This paper investigates the effect of separated exhaust expansion chamber parameters on pressure oscillations in spark-ignited internal combustion (IC) gasoline engines. It is known that exhaust expansion chambers are becoming increasingly more popular among both – original equipment (OE) and aftermarket equipment (AE) exhaust system manufacturers for performance-oriented motorcycles equipped with mainly single cylinder engines, but the companies are reluctant to reveal any detailed principles of operation of the mentioned expansion chambers. The subject of this research is the type of expansion chamber (separate) as used on performance-oriented motorcycles, particularly its’ effect on exhaust pressure pulsations as different chamber volumes, locations and passage sizes are tested. Time-dependent computational fluid dynamics (CFD) analysis was carried out in Solidworks Flow Simulation environment on a simplified exhaust header pipe model imitating engine operation at full load and steady speed. Honda CRF450R motorcycle engine was used as the example and fully defined using a 1D engine performance calculator software to determine the combustion chamber pressure and exhaust valve lift at any given crankshaft position. Volume flow rate of exhaust gasses at the header pipe inlet was calculated based on engine parameters and operating speed. The average pressure values with respect to physical time were measured and graphed across the header pipe inlet cross-section. Eight different header pipe and exhaust expansion chamber combinations were modelled, tested, and results compared at low, medium and high engine speeds. It was found that the presence of exhaust expansion chamber tends to dampen the amplitude and decrease the frequency of pressure oscillations generated at the opening of the exhaust valve(s). Observations show that the addition of an expansion chamber as per design of performance-oriented motorcycles helps to decrease the negative effect of engine tuning while also dampening the positive effect.

An induction motor reliability survey at an egg processing plant shows that almost 50% of the total motor failures are fan induction motors. Visual investigations of the faulty fan motors show that the main cause of the induction motor failure is air gap eccentricity. In this study, experimental tests are performed on a 1.1kW three-phase induction motor to detect air gap eccentricity and overheating of the induction motor. Heating tests show that end shield housing temperature reaches 100°C with blocked air flow from the fan, which can reduce the lifespan of the bearing. Dimension measurements of the end shield housing show that the dimensions of both tested motors back-end shields are larger than ISO tolerance grade limit. It leads to a loose fit between the housing and bearing, causing air gap eccentricity. Also, both motor back end shield housing has an out-of-round condition leading to an unbalanced magnetic pull. To detect the air gap eccentricity caused by too loose of a fit between housing bore and bearing, current Park’s vector approach is used. To measure three phase current, Hall Effect current transducers, a digital oscilloscope is used and Matlab software to process the measurement data. Results show that Park’s vector approach can be used to detect the air gap eccentricity caused by too loose a fit between bearing and housing. Therefore, the Park’s vector approach can be used to diagnose air gap eccentricity and analyse the type of the air gap eccentricity.

An Induction motor reliability survey at an egg processing plant shows that almost 50% of the total motor failures are fan induction motors. Visual investigations of the faulty fan motors show that the main cause of the induction motor failure is air gap eccentricity. In this study, experimental tests are performed on a 1.1kW three-phase induction motor to detect air gap eccentricity and overheating of the induction motor. Heating tests show that end shield housing temperature reaches 100°C with blocked air flow from the fan, which can reduce the lifespan of the bearing. Dimension measurements of the end shield housing show that the dimensions of both tested motors back-end shields are larger than ISO tolerance grade limit. It leads to a loose fit between the housing and bearing, causing air gap eccentricity. Also, both motor back end shield housing has an out-of-round condition leading to an unbalanced magnetic pull. To detect the air gap eccentricity caused by too loose of a fit between housing bore and bearing, current Park’s vector approach is used. To measure three phase current, Hall Effect current transducers, a digital oscilloscope is used and Matlab software to process the measurement data. Results show that Park’s vector approach can be used to detect the air gap eccentricity caused by too loose a fit between bearing and housing. Therefore, the Park’s vector approach can be used to diagnose air gap eccentricity and analyse the type of the air gap eccentricity.

Faba beans (Vicia faba L.) are an excellent protein source and should be more present in human diet, but due to their long cooking time, they are rarely used. So, in order to increase the accessibility of faba beans (Vicia faba L.), experiments were carried out to obtain new food products. Extrusion-cooking was chosen as the potential thermal cooking process and two different products were obtained. One was made exclusively from faba bean (Vicia faba L.) flour, while the second one was produced with a 50% addition of wheat flour to bean flour. Protein content, size, volume mass, pH and starch content for obtained products were analysed in order to characterise the products, as well as to see the differences from non-extruded faba beans (Vicia faba L.) and obtained samples. The experiments were carried out using faba beans (Vicia faba L.) obtained at Ltd. “Pure Horticultural Research Centre”. They were milled at Ltd. “Grauda spēks” and extruded with a twin screw extruder at Ltd. “Milzu”. The experiments showed that the extrusion process had decreased the protein content by 9%, but the starch content had risen by 13% with the addition of wheat flour. But, for sample, without added wheat flour differences were not significant. No significant size differences were observed in the obtained samples and pH values had no significant differences between extruded samples.

Faba beans (Vicia faba L.) are an excellent protein source and should be more present in human diet, but due to their long cooking time, they are rarely used. So, in order to increase the accessibility of faba beans (Vicia faba L.), experiments were carried out to obtain new food products. Extrusion-cooking was chosen as the potential thermal cooking process and two different products were obtained. One was made exclusively from faba bean (Vicia faba L.) flour, while the second one was produced with a 50% addition of wheat flour to bean flour. Protein content, size, volume mass, pH and starch content for obtained products were analysed in order to characterise the products, as well as to see the differences from non-extruded faba beans (Vicia faba L.) and obtained samples. The experiments were carried out using faba beans (Vicia faba L.) obtained at Ltd. “Pure Horticultural Research Centre”. They were milled at Ltd. “Grauda spēks” and extruded with a twin screw extruder at Ltd. “Milzu”. The experiments showed that the extrusion process had decreased the protein content by 9%, but the starch content had risen by 13% with the addition of wheat flour. But, for sample, without added wheat flour differences were not significant. No significant size differences were observed in the obtained samples and pH values had no significant differences between extruded samples.