Heat Transfer Analysis of Supercritical Methane in Microchannels with Different Geometric Configurations On High Power Electromechanical Actuator

The issue of regenerative cooling is one of the most important key technologies of flight vehicles, which is applied into both the engine and high-power electrical equipment. One pattern of regenerative cooling channels is the microchannel heat sinks, which are thought as a prospective means of improving heat removal capacities on electrical equipment of smaller sizes. In this paper, three numerical models with different geometric configurations, namely straight, zigzag, and sinusoid respectively, are built to probe into the thermal hydraulic performance while heat transfer mechanism of supercritical methane in microchannel heat sinks for the heat removal of high-power electromechanical actuator is also explored. In addition, some crucial influence factors on heat transfer such as inlet Reynolds number, operating pressure and heating power are investigated. The calculation results imply the positive effect of wavy configurations on heat transfer and confirm the important effect of buoyancy force of supercritical methane in channels. The heat sinks with wavy channel show obvious advantages on comprehensive thermal performance including overall thermal performance parameter ? and thermal resistance R compared with that of the straight one. The highest Nu and average heat transfer coefficient am appear in the heat sink with zigzag channels, but the pumping power of the heat sink with sinusoidal channels is lower due to the smaller flow loss.

Application of Fuzzy Neural Network PID In Laser-guided Mortar Projectile

Based on the high control performance requirement of laser-guided mortar control system, the permanent magnet synchronous motor (PMSM) is adopted in this paper as the electromechanical actuator of the system, the mathematical model of the motor is analyzed, and the vector control technology is adopted to achieve precise control of position, speed and torque of the electromechanical actuator. Aiming at the characteristics of non-linearity, strong coupling and large parameter changes of the system in flight, an improved fuzzy neural network PID control method is proposed by combining the classical PID control algorithm with fuzzy control and neural network control algorithm to realize the real-time tuning and optimization of PID parameters. The mathematical model of the electromechanical actuator control system is established and simulated. The results show that the fuzzy neural network PID control has good tracking performance, small amplitude error, and strong adaptability to load changes.

Heat transfer analysis of supercritical methane on cooling channel of electromechanical actuator under various flight acceleration overloads

The crucial distinction of heat transfer between the earth environment and the high-acceleration overloads of flight vehicle is the secondary flow resulting from the gravitational buoyancy force and centrifugal one, which influences the heat transfer of supercritical fluid significantly. Hence, in this work, the effect of various flight acceleration overloads on turbulent convection heat transfer in the cooling channel of flight vehicle electromechanical actuator is investigated numerically. The cooling channel is constructed from a helically coiled tube with an inner diameter of 8 mm, coil diameter of 74 mm, and screw pitch of 10 mm, the operation pressure covers the range of 5-9 MPa, and the gravity ranges from 1 g to 50 g. Based on this model, the heat transfer characteristics of supercritical methane in the cooling channel of flight vehicle electromechanical actuator under various acceleration overloads are studied, aiming to obtain a deep understanding of flow and heat transfer mechanism and thermal performance of supercritical methane in the cooling channel under the conditions of actual flight. The simulation result indicates that with the high-g overload, the heat transfer enhancement becomes obvious and the effect of secondary flow caused by the flight acceleration exhibits the non-negligible influence. The secondary flow caused by flight acceleration overloads disturbs the flow acceleration of the main stream that weakens the suppression of heat transfer. However, the effect of gravitational buoyancy does not dominate on forced convection heat transfer even under the high acceleration overload.