High speed and high efficiency synchronized electric motors are favored in the automotive industry and turbo machinery industry worldwide because of the demands placed on efficiency. Herein an electric motor thermal c...High speed and high efficiency synchronized electric motors are favored in the automotive industry and turbo machinery industry worldwide because of the demands placed on efficiency. Herein an electric motor thermal control system using cooling air which enters from the drive end of the motor and exits from the non-drive end of the motor as the rotor experiences dissipates heat is addressed using CFD. Analyses using CFD can help to find the appropriate mass flow rate and windage losses while satisfying temperature requirements on the motor. Here, the air flow through a small annular gap is fed at 620 L/min (0.011 kg/sec) as the rotor spins at 100,000 rpm (10,472 rad/sec) and the rotor dissipates 200 W. The CFD results are compared with experimental results. Based upon the CFD findings, a novel heat transfer correlation suitable for large axial Reynolds number, large Taylor number, small annular gap Taylor-Couette flows subject to axial cross-flow is proposed herein.展开更多
Jet propulsion technology has been limited to being identified largely with turbojets and turbo-machinery driven jet engines.Of late there has been a renewed interest in pulsejet technology and it has once again caugh...Jet propulsion technology has been limited to being identified largely with turbojets and turbo-machinery driven jet engines.Of late there has been a renewed interest in pulsejet technology and it has once again caught the imagination of academia.The specific characteristics of the pulsejet,such as easy scalability,absence of moving parts,reduced combustion temperatures;lower NOX formation and the like make it possess varied capabilities for use in the field of jet propulsion and the most viable option for small-scale jet propulsion.In the current work,a numerical analysis encompassing feasibility and validation of a valveless pulsejet engine was attempted using CD-adapco's STAR-CCM+CFD package.Due to lack of comprehensive established mathematical laws to govern the working of a pulsejet,most experimental work being performed is done by trial and error.This necessitates in-depth computational studies in order to shed more light on the understanding of valveless pulsejets.The results have been encouraging and in agreement with observed experimental conclusions such as,i)changes in dimensions affect the working of a pulsejet,ii)presence of a flare enhances the working of a pulsejet,and the close agreement in the frequency of operation.Through continuous study,an optimum initial condition was achieved which enabled the pulsejet to begin operation even before 0.05 s,thereby greatly reducing computational costs if a higher time-scale were to be used.展开更多
文摘High speed and high efficiency synchronized electric motors are favored in the automotive industry and turbo machinery industry worldwide because of the demands placed on efficiency. Herein an electric motor thermal control system using cooling air which enters from the drive end of the motor and exits from the non-drive end of the motor as the rotor experiences dissipates heat is addressed using CFD. Analyses using CFD can help to find the appropriate mass flow rate and windage losses while satisfying temperature requirements on the motor. Here, the air flow through a small annular gap is fed at 620 L/min (0.011 kg/sec) as the rotor spins at 100,000 rpm (10,472 rad/sec) and the rotor dissipates 200 W. The CFD results are compared with experimental results. Based upon the CFD findings, a novel heat transfer correlation suitable for large axial Reynolds number, large Taylor number, small annular gap Taylor-Couette flows subject to axial cross-flow is proposed herein.
文摘Jet propulsion technology has been limited to being identified largely with turbojets and turbo-machinery driven jet engines.Of late there has been a renewed interest in pulsejet technology and it has once again caught the imagination of academia.The specific characteristics of the pulsejet,such as easy scalability,absence of moving parts,reduced combustion temperatures;lower NOX formation and the like make it possess varied capabilities for use in the field of jet propulsion and the most viable option for small-scale jet propulsion.In the current work,a numerical analysis encompassing feasibility and validation of a valveless pulsejet engine was attempted using CD-adapco's STAR-CCM+CFD package.Due to lack of comprehensive established mathematical laws to govern the working of a pulsejet,most experimental work being performed is done by trial and error.This necessitates in-depth computational studies in order to shed more light on the understanding of valveless pulsejets.The results have been encouraging and in agreement with observed experimental conclusions such as,i)changes in dimensions affect the working of a pulsejet,ii)presence of a flare enhances the working of a pulsejet,and the close agreement in the frequency of operation.Through continuous study,an optimum initial condition was achieved which enabled the pulsejet to begin operation even before 0.05 s,thereby greatly reducing computational costs if a higher time-scale were to be used.
