Engineering Commons^™

Calculation Of Hydraulic Resistance Of A Tubular-Gridse Nozzle With Spiral Turbulizers, Nurmukhamedov Habibulla Sagdullaevich, Mavlonov Elbek Tulkinovich, S.Kh. Nishonova, Kh.S. Nurmukhamedov

Chemical Technology, Control and Management

The article presents the results of an experimental study on the hydraulic resistance of a tubular-grid nozzle made of smooth pipes and pipes with spiral turbulators. Experiments were carried out with nozzles made of smooth pipes and pipes with turbulators. Spiral turbulators are placed discretely with a step t/d=0,3125-0,9375 and installed on a tube sheet in a checkerboard pattern with a step s/d=1,15-10. Experimental studies were carried out with air flow in the transition region.

It has been established that with increasing numerical values of the dimensionless parameter s/d, the resistance of the pipe package decreases from 1,3 to 1,8 …

Research Note: On The Magnitude Of Error In The Calculation Of Mean Room Surface Exitance, James Duff

Articles

Two formulae currently exist for calculating mean room surface exitance. This research note explains and demonstrates that one of these formulae is erroneous under certain conditions and stresses that the alternative expression should generally be used for computing mean room surface exitance.

Scatterer Size Estimation In Pulse-Echo Ultrasound Using Focused Sources: Calibration Measurements And Phantom Experiments, Timothy A. Bigelow, William D. O'Brien

Timothy A. Bigelow

In a companion paper [T. A. Bigelow and W. D. O'Brien Jr., J. Acoust. Soc. Am. 116, 578 (2004)], theory, supported by simulations, showed that accurate scatterer size estimates could be obtained using highly focused sources provided that the derived generalized attenuation-compensation function was used and the velocity potential field near the focus could be approximated as a three-dimensional Gaussian. Herein, the theory is further evaluated via experimental studies. A calibration technique is developed to find the necessary equivalent Gaussian dimensions for a focused source using reflections obtained from a rigid plane scanned through the focus. Then, the theoretical analysis …

Scatterer Size Estimation In Pulse-Echo Ultrasound Using Focused Sources: Theoretical Approximations And Simulation Analysis, Timothy A. Bigelow, William D. O'Brien

Timothy A. Bigelow

The speckle in ultrasound images has long been thought to contain information related to the tissue microstructure. Many different investigators have analyzed the frequency characteristics of the backscattered signals to estimate the scatterer acoustic concentration and size. Previous work has been mostly restricted to unfocused or weakly focused ultrasound sources, thus limiting its implementation with diagnostically relevant fields. Herein, we derive equations capable of estimating the size of a-scatterer for any reasonably focused source provided that the velocity potential field in the focal region can be approximated as a three-dimensional Gaussian beam, scatterers are a sufficient distance from the source, …