Being in Control of Noise Levels Improves the Perception of Airplane Seat Comfort

The aviation industry is constantly making compromises when designing comfortable airplane cabins. Providing passengers with a pleasant acoustic environment without adding weight to the cabin structure is a field of tension that challenges cabin interior designers. The aim of this study was to investigate whether noise levels affect the comfort and physical discomfort experienced by airplane passengers, and whether control influences comfort perception. To this end, 30 participants experienced three conditions (silence, aircraft engine noise at 75 dB, and the same noise with the ability to use earplugs), and comfort and discomfort were measured using a questionnaire. It was concluded that aircraft engine noise negatively affected the airplane passengers’ comfort experiences. Having the ability to control this noisy environment with earplugs resulted in the lowest reported physical discomfort.

Optimization of the exergy efficiency, exergy destruction, and engine noise index in an engine with two direct injectors using NSGA-II and artificial neural network

Direct Dual Fuel Stratification (DDFS) strategy is a novel Low Temperature Combustion (LTC) strategy that has comparable thermal efficiency to the Reactivity Controlled Compression Ignition (RCCI) strategy, while it offers more control over the combustion process and the rate of heat release. The DDFS strategy uses two direct injectors for the low- and high-reactivity fuels (gasoline and diesel) to benefit from the RCCI concept. In this study, the injection strategy of the injectors of a gasoline/diesel DDFS engine was optimized from the thermodynamic perspective to maximize exergy efficiency and minimize exergy destruction and an engine noise index. An artificial neural network was developed with 576 samples from a CFD code to predict the DDFS mode behavior, and the non-dominated sorting genetic algorithm (NSGA-II) was used to obtain the Pareto Front and the optimal solutions. Compared to the base case, the exergy efficiency of the optimal cases increased by up to 2%, exergy destruction and Peak Pressure Rise Rate (PPRR) reduced by about 2.3%, and 2 bar/deg, respectively, in the optimal solutions. NOX and soot emissions were reduced by 40% and 35%, respectively, in the best-case scenarios.

Gasoline Engine Performance, Emissions, Vibration And Noise With Methanol-Gasoline Fuel Blends

The consumption of fossil fuels raises major issues, such as energy availability and environmental preservation. In order to minimize these issues, it is important to propose alternative fuel. Alternative fuel to be proposed should be easy to apply current type of enginethat do not require engine modification and environmentally friendly. This study aims to determine the effect of addition of methanol as a non-fossil fuel mixture into RON 88 gasoline. The ratio of mixture is 80% of RON 88 gasoline and 20% of methanol. We conducted the experiment to determine the mixture effect on fuel properties, engine performance, engine vibration, engine noise, and exhaust emissions. The engine simulation utilized the TV-1 engine (Kirloskar Oil Engines Ltd.). The results show that the engine performance of fuel mixed with methanol tends to be better even though the fuel consumption is higher, the highest specific fuel consumption in the methanol mixture is 2.9 kg/kwh while the specific fuel consumption for gasoline without a methanol mixture is 2.64 kg/kwh. The largest engine vibration occurred in the measurement of the vertical radial direction of 36 m/s2 and 34 m/s2 for with methanol and without the addition of methanol, at 1200 rpm to 1600 rpm respectively. Engine noise is higher for fuel mixed with methanol with the largest value of 86.4 dB compared to 85.7 dB for pure gasoline. Lower emission levels for fuel blended with methanol, where the highest HC emission for pure gasoline is 32 ppm while fuel mixed with methanol is 17 ppm.

Psychoacoustic evaluation of internal combustion engine noises

When buying a car, the acoustic impression of quality of a vehicle drive train is becoming more and more relevant. The perceived sound quality of the engine unit plays a key role here. Due to the nature of individual background noises, that sound quality is negatively influenced. These noise components, which are perceived as unpleasant, need to be further reduced in the course of vehicle development with the identification and evaluation of disruptive noise components in the overall engine noise being a prerequisite for effective acoustics optimization. In particular, the pulsed ticker noise is classified as particularly annoying in Otto DI engines, which is why this article aims to analyze and evaluate the ticking noise components from the overall noise. For this purpose, an empirical formula was developed which can classify the ticking noise components in terms of their intensity. This is purely perception-based and consists of the impulsiveness, the loudness and the sharpness of the overall engine noise. As with other psychoacoustic evaluation scales, the rating was made from 1 (very ticking) to 10 (not ticking). The ticker noise evaluation formula was then verified on the basis of hearing tests with the help of a jury of experts. According to this, it can be predicted precisely in which engine map areas the ticker noise undermines the pleasantness of the overall engine noise.