High Speed Transient Pressure Measurement

To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.

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Pressure measurement and high-speed observation on the cavitation bubble cloud due to the backscattering of HIFU from a laser-induced bubble

Fluid Dynamics Research ◽

10.1088/1873-7005/aae7e4 ◽

2018 ◽

Vol 50 (6) ◽

pp. 065512 ◽

Cited By ~ 4

Author(s):

Toshiyuki Ogasawara ◽

Taisei Horiba ◽

Taisuke Sano ◽

Hiroyuki Takahira

Keyword(s):

Pressure Measurement ◽

Cavitation Bubble ◽

High Speed ◽

Bubble Cloud

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Three-Dimensional CFD Analysis of Meshing Losses in a Spur Gear Pair

Volume 5B: Heat Transfer ◽

10.1115/gt2018-77141 ◽

2018 ◽

Author(s):

T. Fondelli ◽

D. Massini ◽

A. Andreini ◽

B. Facchini ◽

F. Leonardi

Keyword(s):

High Speed ◽

Numerical Study ◽

Fluid Dynamic ◽

Three Dimensional ◽

Spur Gear ◽

Computational Domain ◽

Gear Pair ◽

Transient Pressure ◽

Numerical Effort ◽

Free Environment

The reduction of fluid-dynamic losses in high speed gearing systems is nowadays increasing importance in the design of innovative aircraft propulsion systems, which are particularly focused on improving the propulsive efficiency. Main sources of fluid-dynamic losses in high speed gearing systems are windage losses, inertial losses resulting by impinging oil jets used for jet lubrication and the losses related to the compression and the subsequent expansion of the fluid trapped between gears teeth. The numerical study of the latter is particularly challenging since it faces high speed multiphase flows interacting with moving surfaces, but it paramount for improving knowledge of the fluid behavior in such regions. The current work aims to analyze trapping losses in a gear pair by means of three-dimensional CFD simulations. In order to reduce the numerical effort, an approach for restricting computational domain was defined, thus only a portion of the gear pair geometry was discretized. Transient calculations of a gear pair rotating in an oil-free environment were performed, in the context of conventional eddy viscosity models. Results were compared with experimental data from the open literature in terms of transient pressure within a tooth space, achieving a good agreement. Finally, a strategy for meshing losses calculation was developed and results as a function of rotational speed were discussed.

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Study on connecting tube dynamics for transient pressure measurement

Sadhana ◽

10.1007/s12046-020-1310-y ◽

2020 ◽

Vol 45 (1) ◽

Author(s):

H YADAV ◽

A VENUGOPAL ◽

S V PRABHU ◽

AMIT AGRAWAL

Keyword(s):

Pressure Measurement ◽

Transient Pressure

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An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

Journal of Turbomachinery ◽

10.1115/1.1343465 ◽

2000 ◽

Vol 123 (2) ◽

pp. 418-428 ◽

Cited By ~ 53

Author(s):

Mark P. Wernet ◽

Michelle M. Bright ◽

Gary J. Skoch

Keyword(s):

Flow Field ◽

Centrifugal Compressor ◽

High Speed ◽

Transient Flow ◽

Dynamic Pressure ◽

Rotating Stall ◽

Transient Pressure ◽

Pressure Transducers ◽

Stable Operating ◽

Particle Imaging

Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in high-speed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

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The potential for health risks from intrusion of contaminants into the distribution system from pressure transients

Journal of Water and Health ◽

10.2166/wh.2003.0002 ◽

2003 ◽

Vol 1 (1) ◽

pp. 3-14 ◽

Cited By ~ 103

Author(s):

Mark W. LeChevallier ◽

Richard W. Gullick ◽

Mohammad R. Karim ◽

Melinda Friedman ◽

James E. Funk

Keyword(s):

Health Risks ◽

Negative Pressure ◽

Distribution System ◽

High Speed ◽

Distribution Systems ◽

Transient Pressure ◽

Pressure Transients ◽

Data Loggers ◽

Human Viruses ◽

Treated Drinking Water

The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.

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Experimental and Numerical Investigation on Pressure Fluctuation of the Impeller in an Axial Flow Pump

Volume 5: Multiphase Flow ◽

10.1115/ajkfluids2019-5161 ◽

2019 ◽

Author(s):

Xi Shen ◽

Desheng Zhang ◽

Bin Xu ◽

Yongxin Jin ◽

Xiongfa Gao

Keyword(s):

Pressure Fluctuation ◽

High Speed ◽

Axial Flow ◽

Suction Side ◽

High Speed Photography ◽

Detached Eddy Simulation ◽

Transient Pressure ◽

Unstable Flow ◽

Axial Flow Pump ◽

Flow Pump

Abstract The Detached Eddy Simulation (DES) has been used to simulate the pressure fluctuation of the impeller in an axial flow pump. The results were combined with experiments including high-speed photography and transient pressure measurements to investigate the unstable flow induced by tip leakage vortex (TLV). Numerical results show that maximum predictive error values of head is 2.9%, compared with experimental results. The pressure fluctuation at different monitoring points present a certain regularity, with 3 peaks and 3 troughs in a period, corresponding to the number of blades. The amplitude of pressure fluctuation at P1 (impeller inlet) is the highest among those monitoring points, where the amplitude decreases with the flow rates. The dominant frequency of pressure fluctuation at impeller under cavitation condition is the blade passing frequency (BPF). Besides, there are also N* = 6, 9, 12 and other more harmonic frequencies. The cavitation flow was analyzed with the pressure fluctuation of the blade tip. For the existence of the pressure difference between pressure side and suction side, the pressure at monitoring points change alternately. The amplitude of the fluctuation near tip is affected seriously by the cavitation bubbles, as the cavitation could is a low pressure region with unstable fluctuation.

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