Open-Loop Control of Combustion Instability in Hot-Firing Test Using Gaseous Hydrocarbon Fuel

Active instability control was applied to an atmospheric swirl-stabilized premixed combustor using open loop and closed loop control schemes. Actuation was realised by two on-off valves allowing for symmetric and asymmetric modulation of the premix fuel flow while maintaining constant time averaged overall fuel mass flow. Pressure and heat release fluctuations in the combustor as well as NOx, CO and CO2 emissions in the exhaust were recorded. In the open loop circuit the heat release response of the flame was first investigated during stable combustion. For symmetric fuel modulation the dominant frequency in the heat release response was the modulation frequency, while for asymmetric modulation it was its first harmonic. In stable open loop control a reduction of NOx emissions due to fuel modulation of up to 19% was recorded. In the closed loop mode phase-shift control was applied while triggering the valves at the dominant oscillation frequency as well as at its second subharmonic. Both, open and closed loop control schemes were able to successfully control a low-frequency combustion instability, while showing only a small increase in NOx emissions compared to, for example, secondary fuel modulation. Using premixed open loop fuel modulation, attenuation was best when modulating the fuel at frequencies different from the dominant instability frequency and its subharmonic. The performance of asymmetric fuel modulation was generally slightly better than for symmetric modulation in terms of suppression levels as well as emissions. Suppression of the instability’s pressure rms level of up to 15.7 dB was recorded.

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Responses and Optimization of a PID-Based Speed Regulating System of the Planetary Mixer

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.418-420.1865 ◽

2011 ◽

Vol 418-420 ◽

pp. 1865-1868

Author(s):

Ming Jin Yang ◽

Xi Wen Li ◽

Zhi Gang Wang ◽

Tie Lin Shi

Keyword(s):

Control System ◽

Open Loop ◽

Open Loop Control ◽

Efficient Operation ◽

Loop Control ◽

Loop Control System ◽

Response Optimization ◽

Close Loop Control ◽

Close Loop Control System

The performance of speed regulating is very important to the mixing process with safe, efficient operation and high quality of production. Strategies and practices of responses and optimization of a PID-based speed regulating system of a planetary mixer were presented in this paper. Research results show that: by means of the signal constraint function presented by Simulink Response Optimization, optimization PID parameters of the 2-DOF-PID controller can be obtained, and the response of close-loop control system has quite good performance of overshoot, response time, and stability compared with an open-loop control system.

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Experimental Verification of Open-loop Control for an Underwater Eel-like Robot

The International Journal of Robotics Research ◽

10.1177/0278364902021010095 ◽

2002 ◽

Vol 21 (10-11) ◽

pp. 849-859 ◽

Cited By ~ 17

Author(s):

Kenneth A. Mcisaac ◽

James P. Ostrowski

Keyword(s):

Experimental Work ◽

Experimental Verification ◽

Vision System ◽

Open Loop ◽

Open Loop Control ◽

Loop Control ◽

Position Sensing ◽

Theoretical Predictions ◽

Approximate Expressions ◽

Good Agreement

In this paper, we describe experimental work using an underwater, biomimetic, eel-like robot to verify a simplified dynamic model and open-loop control routines. We compare experimental results to previous analytically derived, but approximate expressions for proposed gaits for forward/backward swimming, circular swimming, sideways swimming and turning in place. We have developed a five-link, underwater eel-like robot, focusing on modularity, reliability and rapid prototyping, to verify our theoretical predictions. Results from open-loop experiments performed with this robot in an aquatic environment using an off-line vision system for position sensing show good agreement with theory.

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