scholarly journals Correction: Persoons, T.; Cressall, R.; Alimohammadi, S. Validating a Reduced-Order Model for Synthetic Jet Actuators Using CFD and Experimental Data. Actuators 2018, 7, 67

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 16
Author(s):  
Tim Persoons ◽  
Rick Cressall ◽  
Sajad Alimohammadi

The authors wish to make the following corrections to this paper [...]

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 67 ◽  
Author(s):  
Tim Persoons ◽  
Rick Cressall ◽  
Sajad Alimohammadi

Synthetic jet actuators (SJA) are emerging in various engineering applications, from flow separation and noise control in aviation to thermal management of electronics. A SJA oscillates a flexible membrane inside a cavity connected to a nozzle producing vortices. A complex interaction between the cavity pressure field and the driving electronics can make it difficult to predict performance. A reduced-order model (ROM) has been developed to predict the performance of SJAs. This paper applies this model to a canonical configuration with applications in flow control and electronics cooling, consisting of a single SJA with a rectangular orifice, emanating perpendicular to the surface. The practical implementation of the ROM to estimate the relationship between cavity pressure and jet velocity, jet velocity and diaphragm deflection and applied driving voltage is explained in detail. Unsteady Reynolds-averaged Navier Stokes computational fluid dynamics (CFD) simulations are used to assess the reliability of the reduced-order model. The CFD model itself has been validated with experimental measurements. The effect of orifice aspect ratio on the ROM parameters has been discussed. Findings indicate that the ROM is capable of predicting the SJA performance for a wide range of operating conditions (in terms of frequency and amplitude).


AIAA Journal ◽  
2005 ◽  
Vol 43 (2) ◽  
pp. 357-369 ◽  
Author(s):  
N. K. Yamaleev ◽  
M. H. Carpenter ◽  
Frederick Ferguson

2004 ◽  
Vol 126 (1) ◽  
pp. 159-165 ◽  
Author(s):  
D. M. Feiner ◽  
J. H. Griffin

This paper is the second in a two-part study of identifying mistuning in bladed disks. It presents experimental validation of a new method of mistuning identification based on measurements of the vibratory response of the system as a whole. As a system-based method, this approach is particularly suited to integrally bladed rotors, whose blades cannot be removed for individual measurements. The method is based on a recently developed reduced-order model of mistuning called the fundamental mistuning model (FMM) and is applicable to isolated families of modes. Two versions of FMM system identification are applied to the experimental data: a basic version that requires some prior knowledge of the system’s properties, and a somewhat more complex version that determines the mistuning completely from experimental data.


Author(s):  
Ahmad M. Bataineh ◽  
Mohammad I. Younis

We study the static and dynamic behavior of electrically actuated micromachined arches. First, we conduct experiments on micromachined polysilicon beams by driving them electrically and varying their amplitude and frequency of voltage loads. The results reveal several interesting nonlinear phenomena of jumps, hysteresis, and softening behaviors. Next, we conduct analytical and theoretical investigation to understand the experiments. First, we solve the Eigen value problem analytically. We study the effect of the initial rise on the natural frequency and mode shapes, and use a Galerkin-based procedure to derive a reduced order model, which is then used to solve both the static and dynamic responses. We use two symmetric modes in the reduced order model to have accurate and converged results. We use long time integration to solve the nonlinear ordinary differential equations, and then modify our model using effective length to match experimental results. To further improve the matching with the experimental data, we curve-fit the exact profile of the microbeam to match the experimentally measured profile and use it in the reduced-order model to generate frequency-response curves. Finally, we use another numerical technique, the shooting technique, to solve the nonlinear ordinary differential equations. By using shooting and the curve fitted function, we found that we get good agreement with the experimental data.


Author(s):  
LM Griffiths ◽  
AL Gaitonde ◽  
DP Jones ◽  
MI Friswell

Reduced order models of computational fluid dynamics codes have been developed to decrease computational costs; however, each reduced order model has a limited range of validity based on the data used in its construction. Further, like the computational fluid dynamics from which it is derived, such models exhibit differences from experimental data due to uncertainty in boundary conditions and numerical accuracy. Model updating provides the opportunity to use small amounts of additional data to modify the behaviour of a reduced order model, which means that the range of validity of the reduced order model can be extended. Whilst here computational fluid dynamics data have been used for updating, the approach offers the possibility that experimental data can be used in future. In this work, the baseline reduced order models are constructed using the Eigensystem realisation algorithm and the steps used to update these models are given in detail. The methods developed are then applied to remove the effects of wind tunnel walls and to include viscous effects.


2017 ◽  
Author(s):  
Tianliang Yu ◽  
George A. Lesieutre ◽  
Steven F. Griffin ◽  
Daniel P. Brzozowski ◽  
Aaron M. Sassoon

Author(s):  
Irsha Pardeshi ◽  
Ashutosh Pandey ◽  
Tom I-P. Shih

Vacuum and low pressures are needed in many applications, and the liquid-ring vacuum pump, which does not have any solid-solid contacts between moving and stationary parts, is widely used because of its low operational cost and long service life. Though progress has been made in advancing this pump, industry still has aggressive goals on improving its efficiency and performance. In this study, a reduced-order model was developed to predict the ability of liquid-ring pumps to ingest air and thereby create lower pressure as a function of pump design and operating parameters. The model developed is semi-empirical — constructed by first analyzing available experimental data to extract features and trends and then encapsulating them into a model through appropriate dimensionless parameters. This model by being in closed form shows the functional relationship between the pump’s design and operating parameters and its ability to ingest air and create a vacuum. To make predictions, this model only requires the following inputs: suction pressure, impeller’s rotational speed, and a few dimensions of the pump. The model developed was assessed by using it to predict the ability of the pump to ingest air for a wide range of suction pressures (cavitation pressure to 760 torr), rotor speeds (up to 1,750 rpm), and dimensions of the pump (radius and span of the impeller blade, hub radius) and then comparing predictions with experimental data not used in the creation of the model. The model developed was found to be accurate within 11% of the experimental data.


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