Observation of Eardrum Movements during Quasi-Static Pressure Changes by High-Speed Digital Imaging

1999 ◽  
Vol 4 (3-4) ◽  
pp. 150-155 ◽  
Author(s):  
Ulrich Vorwerk ◽  
Gunnar Steinicke ◽  
Klaus Begall
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Changes

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

Pressure variation in a fluid at rest (hydrostatics)

2018 ◽  
Author(s):  
Marcel Escudier
Keyword(s):  
Equation Of State ◽  
Static Pressure ◽  
Applied Pressure ◽  
Pressure Variation ◽  
Constant Density ◽  
Fluid Temperature ◽  
Earth’S Atmosphere ◽  
Hydrostatic Equation ◽  
Depth Increase ◽  
Pressure Changes

The three fundamental principles for the variation of static pressure p throughout a body of fluid at rest are (a) the pressure at a point is the same in all directions (Pascal’s law), (b) the pressure is the same at all points on the same horizontal level, and (c) the pressure increases with depth z according to the hydrostatic equation. dp/dz= ρ‎g For a fluid with constant density ρ‎, the increase in pressure over a depth increase h is ρ‎gh, a result which can be used to analyse the response of simple barometers and manometers to applied pressure changes and differences. In situations where very large changes in pressure occur an equation of state may be required to relate pressure and density together with an assumption about the fluid temperature. The hydrostatic equation is still valid but more difficult to integrate, as illustrated by consideration of the earth’s atmosphere.

Vocal Fold Vibratory Characteristics in Normal Female Speakers From High-Speed Digital Imaging

2012 ◽  
Vol 26 (2) ◽  
pp. 239-253 ◽  
Author(s):  
Kartini Ahmad ◽  
Yuling Yan ◽  
Diane M. Bless
Keyword(s):  
Digital Imaging ◽  
Vocal Fold ◽  
High Speed ◽  
Normal Female

scholarly journals Relation between Voice Quality and Pathological Vibratory Patterns Using High-Speed Digital Imaging.

1999 ◽  
Vol 102 (3) ◽  
pp. 354-367 ◽  
Author(s):  
Mamiko Miyaji ◽  
Yoshitake Iwamoto ◽  
Makoto Oda ◽  
Seiji Niimi
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Voice Quality

Experimental Inverstigations On the Pressure Fluctuations in the Sealing Gap of Dry Gas Seals with Embedded Pressure Sensors

2021 ◽  
Author(s):  
Jingjing Luo ◽  
Dieter Brillert
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Static Pressure ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Test Facility ◽  
Experimental Investigations ◽  
Mechanical Seals ◽  
Process Gas ◽  
Sealing Gap

Abstract Dry gas lubricated non-contacting mechanical seals (DGS), most commonly found in centrifugal compressors, prevent the process gas flow into the atmosphere. Especially when high speed is combined with high pressure, DGS is the preferred choice over other sealing alternatives. In order to investigate the flow field in the sealing gap and to facilitate the numerical prediction of the seal performance, a dedicated test facility is developed to carry out the measurement of key parameters in the gas film. Gas in the sealing film varies according to the seal inlet pressure, and the thickness of gas film depends on this fluctuated pressure. In this paper, the test facility, measurement methods and the first results of static pressure measurements in the sealing gap of the DGS obtained in the described test facility are presented. An industry DGS with three-dimensional grooves on the surface of the rotating ring, where experimental investigations take place, is used. The static pressure in the gas film is measured, up to 20 bar and 8,100 rpm, by several high frequency ultraminiature pressure transducers embedded into the stationary ring. The experimental results are discussed and compared with the numerical model programmed in MATLAB, the characteristic and magnitude of which have a good agreement with the numerical simulations. It suggests the feasibility of measuring pressure profiles of the standard industry DGS under pressurized dynamic operating conditions without altering the key components of the seal and thereby affecting the seal performance.

Evaluation of a Flow Measurement Probe Influence on the Flow Field in High Speed Axial Compressors

2021 ◽  
Author(s):  
Ryosuke Seki ◽  
Satoshi Yamashita ◽  
Ryosuke Mito
Keyword(s):  
Flow Field ◽  
Approximation Method ◽  
High Speed ◽  
Static Pressure ◽  
Axial Compressor ◽  
Pressure Change ◽  
Operating Point ◽  
Blade Row ◽  
Probe Insertion ◽  
Probe Geometry

Abstract The aerodynamic effects of a probe for stage performance evaluation in a high-speed axial compressor are investigated. Regarding the probe measurement accuracy and its aerodynamic effects, the upstream/downstream effects on the probe and probe insertion effects are studied by using an unsteady computational fluid dynamics (CFD) analysis and by verifying in two types of multistage high-speed axial compressor measurements. The probe traverse measurements were conducted at the stator inlet and outlet in each case to evaluate blade row performance quantitatively and its flow field. In the past study, the simple approximation method was carried out which considered only the interference of the probe effect based on the reduction of the mass flow by the probe blockage for the compressor performance, but it did not agree well with the measured results. In order to correctly and quantitatively grasp the mechanism of the flow field when the probe is inserted, the unsteady calculation including the probe geometry was carried out in the present study. Unsteady calculation was performed with a probe inserted completely between the rotor and stator of a 4-stage axial compressor. Since the probe blockage and potential flow field, which mean the pressure change region induced by the probe, change the operating point of the upstream rotor and increase the work of the rotor. Compared the measurement result with probe to a kiel probe setting in the stator leading edge, the total pressure was increased about 2,000Pa at the probe tip. In addition, the developed wake by the probe interferes with the downstream stator row and locally changes the static pressure at the stator exit. To evaluate the probe insertion effect, unsteady calculations with probe at three different immersion heights at the stator downstream in an 8-stage axial compressor are performed. The static pressure value of the probe tip was increased about 3,000Pa in the hub region compared to tip region, this increase corresponds to the measurement trend. On the other hand, the measured wall static pressure showed that there is no drastic change in the radial direction. In addition, when the probe is inserted from the tip to hub region in the measurement, the blockage induced by the probe was increased. As a result, operating point of the stator was locally changed, and the rise of static pressure of the stator increased when the stator incidence changed. These typical results show that unsteady simulations including probe geometry can accurately evaluate the aerodynamic effects of probes in the high-speed axial compressor. Therefore, since the probe will pinpointed and strong affects the practically local flow field in all rotor upstream passage and stator downstream, as for the probe measurement, it is important to pay attention to design the probe diameter, the distance from the blade row, and its relative position to the downstream stator. From the above investigations, a newly simple approximation method which includes the effect of the pressure change evaluation by the probe is proposed, and it is verified in the 4-stage compressor case as an example. In this method, the effects of the distance between the rotor trailing edge (T.E.) and the probe are considered by the theory of the incompressible two-dimensional potential flow. The probe blockage decreases the mass flow rate and changes the operating point of the compressor. The verification results conducted in real compressor indicate that the correct blockage approximation enables designer to estimate aerodynamic effects of the probe correctly.

Estimation of glottal area function using stereo-endoscopic high-speed digital imaging

2010 ◽  
Author(s):  
Hiroshi Imagawa ◽  
Ken-Ichi Sakakibara ◽  
Isao T. Tokuda ◽  
Mamiko Otsuka ◽  
Niro Tayama
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Area Function

Performance of Strongly Bowed Stators in a Four-Stage High-Speed Compressor

2004 ◽  
Vol 126 (3) ◽  
pp. 333-338 ◽  
Author(s):  
Axel Fischer ◽  
Walter Riess ◽  
Joerg R. Seume
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Controlled Diffusion ◽  
Stage 4 ◽  
The University

The FVV sponsored project “Bow Blading” (cf. acknowledgments) at the Turbomachinery Laboratory of the University of Hannover addresses the effect of strongly bowed stator vanes on the flow field in a four-stage high-speed axial compressor with controlled diffusion airfoil (CDA) blading. The compressor is equipped with more strongly bowed vanes than have previously been reported in the literature. The performance map of the present compressor is being investigated experimentally and numerically. The results show that the pressure ratio and the efficiency at the design point and at the choke limit are reduced by the increase in friction losses on the surface of the bowed vanes, whose surface area is greater than that of the reference (CDA) vanes. The mass flow at the choke limit decreases for the same reason. Because of the change in the radial distribution of axial velocity, pressure rise shifts from stage 3 to stage 4 between the choke limit and maximum pressure ratio. Beyond the point of maximum pressure ratio, this effect is not distinguishable from the reduction of separation by the bow of the vanes. Experimental results show that in cases of high aerodynamic loading, i.e., between maximum pressure ratio and the stall limit, separation is reduced in the bowed stator vanes so that the stagnation pressure ratio and efficiency are increased by the change to bowed stators. It is shown that the reduction of separation with bowed vanes leads to a increase of static pressure rise towards lower mass flow so that the present bow bladed compressor achieves higher static pressure ratios at the stall limit.

scholarly journals Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1974
Author(s):  
Jiří Fürst ◽  
Martin Lasota ◽  
Jan Lepicovsky ◽  
Josef Musil ◽  
Jan Pech ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Incidence Angle ◽  
Blade Loading ◽  
Linear Cascade ◽  
Pressure Distributions ◽  
Blade Cascade ◽  
Loading Function ◽  
Stationary Approach ◽  
Dimensional Section

The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerodynamic excitation forces and approximation of the unsteady blade-loading function using a quasi-stationary approach. The numerical simulations were performed with an in-house finite-volume code built on the top of the OpenFOAM framework. The experimental data were acquired for regimes corresponding to the numerical setup. The comparison of the computational and experimental results is shown for the static pressure distributions on three blades and upstream and downstream of the cascade. The plot of the aerodynamic moments acting on all five blades shows that the adjacent blades are significantly influenced by the angular offset of the middle blade.

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