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In the present research work, computational simulation of the double cavity scramjet combustor have been performed by using the two-dimensional compressible Reynolds-Averaged Navier–Stokes (RANS) equations coupled with two equation standard k–ɛ turbulence model as well as the finite-rate/eddy-dissipation reaction model. All the simulations are carried out using ANSYS 14-FLUENT code. Additionally, the computational results of the present double cavity scramjet combustor have been compared with experimental results for validation purpose which is taken from the literature. The computational outcomes are in satisfactory agreement with the experimentally obtained shadowgraph image and pressure variation curve. However, due to numerical calculation, the pressure variation curve obtained computationally is under-predicted in 5 locations. Further, analyses have been carried out to investigate the effect of variation of hydrogen injection pressure as well as the variation of air inlet temperature on the flow-field characteristics of scramjet engine keeping the Mach number constant. The obtained results show that the increase in hydrogen injection pressure is followed by the generation of larger vortex structure near the cavity regions which in turn helps to carry the injectant and also enhance the air/fuel mixing whereas the increase in the inlet temperature of air is characterised by the shifting of incident oblique shock in the downstream of the H2 injection location. Again for T0 = 1500 K, the combustion phenomena remains limited to the cavity region and spreads very little towards the downstream of the combustor.

Optimized robust control for Polymer Electrolyte Membrane Fuel Cell (PEMFC) air-feed systems is an important challenge in improving the net fuel cell power output in automotive applications. This paper focuses on the practical implementation and performance comparison of robust and adaptive Second Order Sliding Mode Controllers (SOSMC) for this application. Both controllers aim to minimize the power consumption of the air-feed system by operating it to maintain the optimal oxygen excess ratio in the fuel cell. The controllers have been tested using a Hardware-In-Loop test bench based on a commercial twin screw compressor and 90 Cell, 33 kW fuel cell emulator. The experimental results demonstrate the effectiveness of both controllers and highlight that the adaptive controller is more power-efficient as the adaptive gains further reduce the internal power consumption of the air-feed system.

In this paper, an adaptive algebraic observer is proposed for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) air-feed system, based on Higher Order Sliding Mode (HOSM) differentiators. The goal is to estimate oxygen and nitrogen partial pressures in the fuel cell cathode side, using measurements of supply manifold pressure and compressor mass flow rate. As the proposed technique requires the time derivatives of the states, Lyapunov-based adaptive HOSM differentiators are synthesized and implemented for estimating these derivatives without a-priori knowledge of the upper bounds of their higher order time derivatives. The performance of the proposed method is validated through experiments on a Hardware-In-Loop (HIL) test bench. These results illustrate the feasibility and effectiveness of the proposed approach.

This paper provides a reliable tool for simulating the effects of exhaust gas flow through the variable turbine geometry section of a variable geometry turbocharger (VGT), on flow control mechanism. The main objective is to estimate the resistive aerodynamic force exerted by the flow upon the variable geometry vanes and the controlling actuator, in order to improve the control of vane angles. To achieve this, a 1D model of the exhaust flow is developed using Navier–Stokes equations. As the flow characteristics depend upon the volute geometry, impeller blade force and the existing viscous friction, the related source terms (losses) are also included in the model. In order to guarantee stability, an implicit numerical solver has been developed for the resolution of the Navier–Stokes problem. The resulting simulation tool has been validated through comparison with experimentally obtained values of turbine inlet pressure and the aerodynamic force as measured at the actuator shaft. The simulator shows good compliance with experimental results.

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are extremely sensitive to load variations. A rapid load variation can damage the system in many ways. For this reason, a Load Governor (LG) based on constrained Extremum Seeking (ES) approach has been proposed in this paper. The LG controller ensures that the physical constraints of the system are not violated and the ES controller varies the LG bandwidth parameter to optimize the net power output. The proposed controller has been tested on a Hardware-In-Loop (HIL) emulation test bench, based on a commercial centrifugal compressor and a real time PEMFC emulator. Experimental results show a good performance of the proposed scheme during load variations.

This article is focused on the working, modeling and control of pancake DC torque motors, used in automobile engine air path actuators. These motors, with a limited working angle, provide high torque which makes them suitable for use in actuators without any additional gear reduction. The torque is a nonlinear function of the motor angle. This article provides a modeling scheme, suitable for control purposes, which takes into consideration nonlinearities arising from friction and operating temperature. Comparison between simulation and experiments shows the effectiveness of the proposed model. Second order sliding mode control has been applied to the actuators for robust control under the influence of nonlinearities and uncertainties. The effectiveness of the control algorithm has been proven experimentally.

In this article, we have addressed the control problem of unicycle path following, using a rigidly attached target point. The initial path following problem has been transformed into a reference trajectory following problem, using saturated control laws and a geometric characterization hypothesis. This hypothesis links the curvature of the path to be followed with the target point. The proposed controller allows global stabilization, without restrictions on initial conditions. The effectiveness of this controller is illustrated through simulations.

This paper presents the application of higher order Sliding Mode observers (SMO) for state observation and friction estimation of an engine air path actuator. The actuator model incorporates LuGre Friction Model for dynamic friction modeling. The study has two objectives, to observe the system dynamics and the friction dynamics, and to use the equivalent output injection to estimate the parameters of the LuGre model. Cascaded sliding mode observers have been used to observe system and friction dynamics separately. Friction force has been estimated using the Equivalent output injection of the observer, considering friction as an unknown external input. Through this estimation, identification of the LuGre model parameters becomes simplified. Simulation and experimental results show the effectiveness of the proposed observation and identification scheme.

Laboratoire OPERA, Universite de Technologie de Belfort-Montbeliard, Belfort, FranceTheauthorsregretthatthecorrespondingauthoraffiliationwaslistedincorrectly.Thecorrespondingauthoraffiliationshouldbelisted as follows:* Corresponding author: Control Science and Engineering, Harbin Institute of Technology, Harbin, China.The authors would like to apologize for any inconvenience.