Particles mass flow rate and concentration measurement using electrostatic sensor

In many industries where flow parameters measurement is essential to control manufacturing process, the use of a reliable, cost effective and high accuracy instrument is an important issue. Appropriate measurement method and design leads to improvement of pneumatic conveyors operation and process efficiency. This paper present an instrumentation design based on passive charge detection using a single electrostatic sensor. Two different sensor electrodes are applied to show the flexibility of electrostatic sensor application. A time domain signal processing algorithm is developed to measurement of mass flow rate and concentration profile from acquired electrical charge signal. The findings is led to a low cost and high accuracy design, the experimental test results of the design shows less than ±5% error between measured parameters and reference reading acquired from the manual weighing

ADAPTIVE METHOD TO PREDICT AND TRACK UNKNOWN SYSTEM BEHAVIORS USING RLS AND LMS ALGORITHMS

This study investigates the ability of recursive least squares (RLS) and least mean square (LMS) adaptive filtering algorithms to predict and quickly track unknown systems. Tracking unknown system behavior is important if there are other parallel systems that must follow exactly the same behavior at the same time. The adaptive algorithm can correct the filter coefficients according to changes in unknown system parameters to minimize errors between the filter output and the system output for the same input signal. The RLS and LMS algorithms were designed and then examined separately, giving them a similar input signal that was given to the unknown system. The difference between the system output signal and the adaptive filter output signal showed the performance of each filter when identifying an unknown system. The two adaptive filters were able to track the behavior of the system, but each showed certain advantages over the other. The RLS algorithm had the advantage of faster convergence and fewer steady-state errors than the LMS algorithm, but the LMS algorithm had the advantage of less computational complexity

FOREIGN OBJECT DAMAGE ON THE LEADING EDGE OF COMPRESSOR BLADES

Foreign object damage (FOD) usually happens when objects are sucked into jet engines powering military or civil aircraft. Under extreme conditions, FOD can lead to severe structural damage. More commonly it produces locally impacted sites of the fan and compressor airfoils, reducing fatigue life of these components. FOD is a prime cause for repair in aircraft engines. In this study, the impact on the edge of a thin plate is examined by using the finite element method. The second step in the analysis focuses on the comparison between quasi-static indentation and fully dynamic impact for three critical locations where residual hoop stresses are tensile

Particle size measurement using electrostatic sensor through spatial filtering method

Particle size measurement is important in powder and particle industries in which the particle size affects the productivity and efficiency of the machine, for example, in coal-fired power plants. An electrostatic sensor detects the electric charge from dry particles moving in a pipeline. Analysis of the detected signal can provide useful information about the particle velocity, mass flow rate, concentration and size. Using electrostatic sensors, previous researches studied particle sizing using magnitude dependent analysis which is a highly conditional method where the results can be affected by other parameters such as particle mass flow rate, velocity and concentration. This research proposes a magnitude independent analysis for particle sizing in the frequency domain called spatial filtering method. The solution was started by modeling and analysis of the charge induced to the ring electrode using finite-element analysis to find the sensitivity of electrode. A mathematical model was provided to compute particle position on the radial axis of the electrode and then a new technique was proposed to extract a single particle size from the calculated particle radial position. To validate the proposed method experimentally, a sensor was designed and five test particles ranging from 4 mm to 14 mm were selected for measurement. The results show a 0.44 mm estimation error between the estimated and expected results. The results also show that the method is promising for the establishment of a reliable and cost-effective solid particle sizing system

Active control of a lumped acoustic source driven by various actuators

This paper studies an acoustic source with a relatively small thickness and high bending stiffness. The high bending stiffness is obtained with a sandwich structure in which the face of the sandwich structure internal to the source is perforated to increase the acoustic compliance. Multiple actuators are used to drive the moving component of the acoustic source. Feedback and feedforward damping control techniques are used to actively obtain a smooth frequency response, especially at low frequencies. Such a compensation scheme generally leads to amplification of the lower frequencies and may result in a significant electrical input power. In addition, a part of the input power is stored in mechanical and acoustical elements of the acoustic source. Voice coil and piezoelectric actuators are compared regarding the ability to recover the stored energy. Piezoelectric actuators are particularly attractive from energy recovery point of view because the acoustic source has to operate in the low frequency, quasi-static regime. The two-way energy ?ow between the actuator and a connected ampli?er is investigated. In particular, the effectiveness of energy recovery from the reactive components of the acoustic source is evaluated to improve the overall radiation ef?ciency. A lumped model is used to represent the acoustic source that is excited by a stacked piezoelectric element. The required power supply and resulting radiation ef?ciency are evaluated when a conventional analogue ampli?er is used. The result is compared to the case in which some parts of the stored power are recovered and sent back to the connected switching amplifier. It was found that approximately 66% of the reactive power stored in the acoustic source can be recovered. The study also reveals a significant increase in overall system ef?ciency and more than 80% decrease in the amount of required input power through recovering the reactive power in the system

On Lagerstrom’s Model of Slow Incompressible Viscous Flow

The model discussed is a nonlinear boundary value problem which contains a parameter $\varepsilon$ that models the Reynolds number. The matched asymptotic expansions, an inner “Stokes” expansion valid near the inner boundary and an outer “Oseen” expansion valid away from it, that describe the solutions of the model problem for $\varepsilon$ small are extended. Numerical calculations show that these matched expansions have only a small range of usefulness, with the addition of further terms generally causing a worse, rather than better, approximation at moderate values of $\varepsilon$. Far better results are achieved when a single expansion, the outer expansion, is used throughout. The additional terms that have been calculated then consistently give improved approximations for all $\varepsilon$. It is also rigorously proved that an iterative method of solution of the model equation based on the outer “Oseen” approximation, converges for all $\varepsilon$ to a unique solution.\ud The results presented here for Lagerstrom’s model suggest that iterative improvement of the Oseen expansion may be an effective method of approximation of viscous flows at moderate Reynolds number

A method for solving systems of non-linear differential equations with moving singularities

We present a method for solving a class of initial valued, coupled, non-linear differential equations with `moving singularities' subject to some subsidiary conditions. We show that this type of singularities can be adequately treated by establishing certain `moving' jump conditions across them. We show how a first integral of the differential equations, if available, can also be used for checking the accuracy of the numerical solution.Comment: 9 pages, 7 eps figures, to appear in Comput. Phys. Co