A highly non-linear model for the dynamics behavior of Air Cushion Vehicles (ACV) is presented. In this model the compressible Bernoulli's equation, the Newton's second law of motion, and the nonlinear isentropic relations are used to predict the dynamics behavior of only the vertical response of the ACV in both time and frequency domains. In this paper the mass flow rate inside the air cushion volume of the ACV is maintained constant. In order to assist in the design process of such vehicles, the self excited response and the cushion pressure of the ACV are calculated to understand the dynamic behavior of these vehicles. It is shown in this study that the mass flow rate and the length of the vehicle's skirt are the most significant parameters which control the steady state behavior of the self excited oscillations of the ACV. An equation to predict the transient time of the oscillatory response or the settling time in terms of the system parameters is developed. Based on the developed equations, the optimum parameters of the ACV that lead to minimum settling time are obtained. Also, the chaotic behavior of the heave dynamics is investigated with the aid of the Fourier analysis and the Poincaré map. It is shown that the heave dynamics does not manifest any chaotic behavior within the selected range of the control parameters. However, the cushion pressure manifested some chaotic behavior at some values of the skirt length and mass flow rate.
A model for compressible Air Cushion Vehicles (ACV) is presented. In this model the compressible Bernoulli's equation and the Newton's second law of motion are used to predict the dynamic behavior of the heave response of the ACV in both time and frequency domains. The mass flow rate inside the air cushion of this model is assumed to be constant. The self excited response and the cushion pressure of the ACV is calculated to understand the behavior of the system in order to assist in the design stage of such systems. It is shown in this study that the mass flow rate and the length of the vehicle's skirt are the most significant parameters which control the steady state behavior of the self excited oscillations of the ACV. An equation to predict the transient time of the oscillatory response or the settling time in terms of the system parameters of the ACV is developed. Based on the developed equations, the optimum parameters of the ACV that lead to minimum settling time are obtained.
Heat produced inside internal combustion engines can become the cause of engine damage and failure. The engine cooling system in vehicles plays a crucial role to avoid damage as a result of internal heating. Thus, the role of radiators in removing excessive heat from the engine is important. Nanofluids are used in this regard to improve the heat transfer performance of radiators. Among different nanofluids, Al2O3/water and ZnO/water nanofluids have been proven better heat transfer coolants for automobile cooling systems. Therefore, in this study, we developed the automotive radiator test rig to compare the performance of ZnO/water and Al2O3/water nanofluids. The radiator test rig was modified to find accurate results. The overall comparison between both nanofluids showed that Al2O3 nanoparticles are more effective as compared to ZnO nanoparticles in the coolant.
In this study, three degrees of freedom nonlinear air cushion vehicle (ACV) model is introduced to examine the dynamic behavior of the heave and pitch responses in addition to the cushion pressure of the ACV in both time and frequency domains. The model is based on the compressible flow Bernoulli's equation and the thermodynamics nonlinear isentropic relations along with the Newton’s second law of translation and rotation. In this study, the dynamical investigation was based on numerical simulation using the stiff ODE solvers of the Matlab software. The chaotic investigations of the proposed model is provided using the Fast Fourier Transform (FFT), the Poincaré maps, and the regression analysis. Three control design parameters are investigated for the chaotic studies. These parameters are: ACV mass (M), the mass flowrate entering the cushion volume (m ̇_in), and the ACV base radius (r). Chaos behavior was observed for heave, and pitch responses as well as the cushion pressure.
In this study, a three degrees of freedom nonlinear air cushion vehicle (ACV) model is introduced to examine the dynamic behavior of the heave and pitch responses in addition to the cushion pressure of the ACV in both time and frequency domains. The model is based on the compressible flow Bernoulli’s equation and the thermodynamics nonlinear isentropic relations along with the Newton second law of translation and rotation. In this study, the dynamical investigation was based on a numerical simulation using the stiff ODE solvers of the Matlab software. The chaotic investigations of the proposed model are provided using the Fast Fourier Transform (FFT), the Poincaré maps, and the regression analysis. Three control design parameters are investigated for the chaotic studies. These parameters are: ACV mass (M), the mass flow rate entering the cushion volume (ṁin
), and the ACV base radius (r). Chaos behavior was observed for heave, and pitch responses as well as the cushion pressure.
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