High-Pressure Vibrating Pressure Transducer

There is a need to measure static and dynamic conditions in many gas turbine applications, in particular for combustion instabilities, such as those in the afterburner. The DC and low frequency components are typically used for conventional engine control, while the high frequency data is essential for acoustic screech and rumble diagnostics and control. This paper presents a static-dynamic piezoresistive pressure transducer that measures low amplitude, dynamic pressure perturbations superimposed on top of a high pressure through the implementation of low pass mechanical structures. The transducer, which is capable of operating at ultra-high temperatures and in harsh environments, consists of a static piezoresistive pressure transducer, which measures the large pressures on the order of 200psi and greater, and an ultrasensitive, dynamic piezoresistive pressure transducer which captures small, high frequency pressure oscillations on the order of a few psi. The heightened sensitivity in high pressure environments is achieved by filtering the measured pressure of high frequency content through an innovative low pass mechanical filter structure. The large static pressures passed by the low-pass mechanical filter structures are routed to the backside of the dynamic pressure sensor, which results in both the front and the back of the dynamic sensor being exposed to the large pressures within the environment. Therefore, the large static pressures cancel out, and the dynamic sensor only senses the low magnitude, high frequency pressure perturbations. This dual sensor, static-dynamic pressure transducer reproduces pressure signals with sensitivity far higher than any single high pressure transducer available today. The dual sensor, static-dynamic transducer meets the pressure sensing specification of numerous applications including, but not limited to, the following: the optimization of turbine operation, turbine design and testing, the detection of the onset of rotating stall and surge in turbine compressors, and combustion instabilities. This paper describes a six element model of the static-dynamic transducer’s low-pass mechanical filtering structures. The paradigm is derived from first-principles of fluid motion in acoustic ducts with viscous dissipation. A dynamic pressure source is used to verify the model and its operation. Finally, a transfer function characterization of a fully operational static-dynamic pressure transducer over a wide bandwidth is presented. Based upon the analytical and experimental results, the static-dynamic pressure transducer will make it possible for turbine users and manufacturers to implement ultra-sensitive pressure monitoring to reduce compressor and combustion instabilities [1] [2].

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Osmotic and activity coefficients of sodium sulphate in water from 150 to 250 °C

Canadian Journal of Chemistry ◽

10.1139/v82-240 ◽

1982 ◽

Vol 60 (13) ◽

pp. 1754-1758 ◽

Cited By ~ 9

Author(s):

Om N. Bhatnagar ◽

A. N. Campbell

Keyword(s):

Aqueous Solution ◽

High Pressure ◽

Activity Coefficients ◽

Pressure Measurement ◽

Vapour Pressure ◽

Pressure Transducer ◽

Solute Concentration ◽

Sodium Sulphate ◽

Thermodynamic Quantities ◽

High Pressure Cell

Osmotic and activity coefficients of sodium sulphate in aqueous solution have been determined at temperatures up to 250 °C, at solute concentration from 0.3 m to saturation, by measurements of vapour pressure using a newly designed high pressure cell. A precision pressure transducer is used in this cell for pressure measurement. Certain thermodynamic quantities have been calculated from the activity coefficients.

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Operation Cycle of Diesel CR Injection Pump via Pressure Measurement in Piston Working Chamber

Energies ◽

10.3390/en14175385 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5385

Author(s):

Ornella Chiavola ◽

Edoardo Frattini ◽

Simone Lancione ◽

Fulvio Palmieri

Keyword(s):

High Pressure ◽

Pressure Transducer ◽

Pressure Rise ◽

Operating Characteristics ◽

Operating Cycle ◽

Working Chamber ◽

Injection Pump ◽

Pressure Injection ◽

Set Up ◽

High Pressure Injection

The paper is devoted to the analysis of the operating cycle of a high-pressure injection pump used in common rail systems. The investigation is based on experimental activities, and it is carried out in a novel pump set-up that allows measurements of the instantaneous pressure in the piston working chamber. A single plunger pump has been equipped with a piezo-resistive pressure transducer which allows for the measurement of the pressure signal during pump operation on a test rig. The paper describes the experimental set-up, the modified injection pump equipped with the pressure transducer, and the experimental tests carried out. Main results obtained using a standard commercial diesel fuel are discussed at first; secondly, the focus moves on to the use of an alternative fuel (biodiesel) whose features in terms of bulk modulus, viscosity, and density significantly differ from the reference fuel. Based on the characteristics of the pump operating cycle, the fuel suction and delivery processes are analyzed, pointing out how the used fuel type is reflected on them. The investigations are aimed at describing the operating characteristics of the pump, focusing the attention on those features playing a fundamental role on the global efficiency of the pump. The amplitudes of the pump-work phases, the ranges of pressure fluctuations, and the pressure-rise rates are quantified and reported, providing crucial indications for lumped parameter modeling and design activities in the field of current generation high-pressure injection pumps.

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