A significant portion of the energy produced by combustion inside an engine is rejected as heat. Though it is impossible to prevent heat rejection, reducing the amount of heat rejected will help to increase the useful energy. Low heat rejection engine is a solution to these problems as they supply designers with insulation properties. In the design of adiabatic engines, reducing heat rejection in cylinder requires the use of special type of insulation often referred to as thermal barrier coatings in the combustion chamber of the engine. This insulation especially on engine piston is considered as a solution for the reduction of unburned HC emissions caused by incomplete combustion with respect to crevice volume when engines start. The insulation layer in effect reduces the thermal conductivity and raises the oxidation of the unburned charge such that the metallic substrates are exposed to lower peak temperatures, thus reducing the thermal stress in engine components. In this work piston is modelled using CATIA V5R16. For analyzing the effects of insulation layer on the piston, thermal analysis is conducted using finite element method in ANSYS after applying thermal boundary conditions. By changing the coating thickness and performing thermal analysis on each coating thickness followed by the use of mathematical operations enables the optimization of piston coating thickness. This optimized coating thickness is validated using Genetic Algorithm.
Purpose
The purpose of this paper is to design an electromechanical actuator which can inherently tolerate a stuck or loose failure without any need for fault detection isolation and reconfiguration.
Design/methodology/approach
Generalized design methodology for a thrust vector control application is adopted to reduce the design iterations during the initial stages of the design. An optimum ball screw pitch is selected to minimize the motor sizing and maximize the load acceleration.
Findings
A high redundancy electromechanical actuator for thrust vector control has lower self-inertia and higher reliability than a direct drive simplex configuration. This configuration is a feasible solution for thrust vector control application because it offers a more acceptable and graceful degradation than a complete failure.
Research limitations/implications
Future work will include testing on actual hardware to study the transient disturbances caused by a fault and their effect on launch vehicle dynamics.
Practical implications
High redundancy electromechanical actuator concept can be extended to similar applications such as solid motor nozzle in satellite launch vehicles and primary flight control system in aircraft.
Social implications
High redundancy actuators can be useful in safety critical applications involving human beings. It can also reduce the machine downtime in industrial process automation.
Originality/value
The jam tolerant electromechanical actuator proposed for the launch vehicle application has a unique configuration which does not require a complex fault detection isolation and reconfiguration logic in the controller. This enhances the system reliability and allows a simplex controller having a lower cost.
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