Feedback control of thermoacoustic system's load which maintains steady-state pressure amplitude for temperature variation

2018 ◽  
Vol 2018.55 (0) ◽  
pp. J045
Author(s):  
Akihito INOUE ◽  
Yasuhide KOBAYASHI
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Temperature Variation ◽  
Pressure Amplitude ◽  
State Pressure

Study of Temperature Effect on Servovalve-Controlled Fuel Metering Unit

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Bin Wang ◽  
Haocen Zhao ◽  
Ling Yu ◽  
Zhifeng Ye
Keyword(s):  
Steady State ◽  
Temperature Variation ◽  
Dynamic Characteristics ◽  
Numerical Study ◽  
Step Response ◽  
Fuel Temperature ◽  
Wide Range ◽  
Fuel Rate ◽  
Testing Condition ◽  
The Given

It is usual that fuel system of an aero-engine operates within a wide range of temperatures. As a result, this can have effect on both the characteristics and precision of fuel metering unit (FMU), even on the performance and safety of the whole engine. This paper provides theoretical analysis of the effect that fluctuation of fuel temperature has on the controllability of FMU and clarifies the drawbacks of the pure mathematical models considering fuel temperature variation for FMU. Taking the electrohydraulic servovalve-controlled FMU as the numerical study, simulation in AMESim is carried out by thermal hydraulic model under the temperatures ranged from −10 to 60 °C to confirm the effectiveness and precision of the model on the basis of steady-state and dynamic characteristics of FMU. Meanwhile, the FMU testing workbench with temperature adjustment device employing the fuel cooler and heater is established to conduct an experiment of the fuel temperature characteristics. Results show that the experiment matches well with the simulation with a relative error no more than 5% and that 0–50 °C fuel temperature variation produces up to 5.2% decrease in fuel rate. In addition, step response increases with the fuel temperature. Fuel temperature has no virtual impact on the steady-state and dynamic characteristics of FMU under the testing condition in this paper, implying that FMU can operate normally in the given temperature range.

Transient Vibration and Feedback Control of an Inductrack Maglev System

2020 ◽  
Author(s):  
Ruiyang Wang ◽  
Bingen Yang ◽  
Hao Gao
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Dynamic System ◽  
Permanent Magnets ◽  
Preliminary Investigation ◽  
Lookup Table ◽  
Lumped Mass ◽  
Transient Vibration ◽  
Transient Model ◽  
Halbach Arrays

Abstract As a new strategy for magnetic levitation envisioned in 1990s, the Inductrack system with permanent magnets (PMs) aligned in Halbach arrays has been intensively studied and applied in many projects. Due to the nonlinear, time-varying electro-magneto-mechanical coupling in such a system, the dynamic behaviors are complicated with transient responses, which in most cases can hardly be predicted with fidelity by a steady-state Inductrack model. Presented in this paper is a benchmark 2-DOF transient Inductrack model, which is derived from the first laws of nature, without any assumed steady-state quantities. It is shown that the dynamic response of the Inductrack dynamic system is governed by a set of nonlinear integro-differential equations. As demonstrated in numerical simulations with the transient model, unstable vibrations in the levitation direction occur when the traveling speed of the vehicle exceeds a threshold. To resolve this instability issue, feedback control is implemented in the Inductrack system. In the development, an assembly of Halbach arrays and active coils that are wound on the PMs is proposed to achieve a controllable source magnetic field. In this preliminary investigation, the proposed control system design process takes two main steps. First, a PID controller is set and tuned based on a simple lumped-mass dynamic system. Second, the nonlinear force-current correlation is obtained from a lookup table that is pre-calculated by steady-state truncation of the full transient Inductrack model. With the implemented feedback control algorithms, numerical examples display that the motion of the vehicle in levitation direction can be effectively stabilized at different traveling speeds. Although only a 2-DOF transient model is used here, the modeling technique and the controller design approach developed in this work are potentially applicable to more complicated models of Inductrack Maglev systems.

scholarly journals Analysis and design of the plug-in type repetitive control system based on steady-state residual convergence ratio

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141985097
Author(s):  
Xianliang Jiang ◽  
Huajie Hong
Keyword(s):  
Control System ◽  
Steady State ◽  
Feedback Control ◽  
Control Method ◽  
Time Lag ◽  
Repetitive Control ◽  
Stable Condition ◽  
Design Guidelines ◽  
Design Algorithm ◽  
Analysis And Design

In the feedback control robotic systems, the repetitive control method has a high control performance for the track or elimination of the periodic signals. The promotion of the plug-in type configuration of the controller broadens the application range and applicability of the control method. In this article, a novel design algorithm based on the steady-state residual convergence ratio of the repetitive control system is proposed to improve the performance of the stabilized platform to resist the periodic perturbation. The basic structure and stable condition of the plug-in type repetitive control method are first introduced by applying the small gain theorem and the stability theorem for time-lag systems. Then the analysis of the convergence rate is utilized in constructing the basic index of the design algorithm of a plug-in type repetitive control system based on a steady-state residual convergence ratio. The parameters of the designed controller are checked by the validity condition of the plug-in type repetitive control system, and a simulation example is given to verify the effectiveness of the design algorithm. The article provides basic design guidelines and schemes for the design of the periodic disturbance suppression performance of the feedback control system. In the final physical prototype experiment, the prospective steady-state residual convergence ratio is basically achieved within the allowable range of error.

scholarly journals Creating Nodes at Selected Locations in a Harmonically Excited Structure Using Feedback Control and Green’s Function

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Bassam A. Albassam
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Green’S Function ◽  
Green's Function ◽  
Nodal Point ◽  
Control Force ◽  
Velocity Measurements ◽  
Numerical Examples ◽  
Control Forces

The paper deals with designing a control force to create nodal point(s) having zero displacements and/or zero slopes at selected locations in a harmonically excited vibrating structure. It is shown that the steady-state vibrations at desired points can be eliminated using feedback control forces. These control forces are constructed from displacement and/or velocity measurements using sensors located either at the control force position or at some other locations. Dynamic Green’s function is exploited to derive a simple and exact closed from expression for the control force. Under a certain condition, this control force can be generated using passive elements such as springs and dampers. Numerical examples demonstrate the applicability of the method in various cases.

scholarly journals A Numerical Solution of a Surface Crack Under Cyclic Hydraulic Pressure Loading

1997 ◽  
Vol 119 (4) ◽  
pp. 637-645 ◽  
Author(s):  
Z.-Q. Xu ◽  
K. J. Hsia
Keyword(s):  
Steady State ◽  
Crack Growth ◽  
Surface Crack ◽  
Rolling Contact ◽  
Hydraulic Pressure ◽  
Crack Mouth ◽  
Pressure Loading ◽  
Governing Equations ◽  
Time Step ◽  
State Pressure

Material degradation and failure in rolling contact components are often associated with surface crack initiation and propagation under repeated contact loading. In the presence of lubricating fluid, the hydraulic pressure in the fluid film between the contacting surfaces may play an important role in the crack growth process. This paper presents a method to model the effect of hydraulic pressure loading on surface crack growth. The governing equations of the coupled viscous fluid/cracked solid problem are obtained, which are nonlinear integral and differential equations. The fluid is assumed to be Newtonian and incompressible. The cracked solid is considered to be linearly elastic. Pressure loading history is prescribed at the crack mouth. Finite difference methods are used to solve the governing equations. For each time step, Newton-Raphson iteration method is used to search for the root of the nonlinear equations. Both transient and steady-state pressure distributions under cyclic pressure loading are obtained using this method. A few numerical examples are given to demonstrate the reliability and effectiveness of the solution method. The solution shows that there exists a characteristic time, which determines whether pressure fluctuations at the crack mouth can be transmitted deep into the crack. The steady-state pressure distribution exhibits a phase delay from the applied cyclic loading.

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