Topic
Back pressure
About: Back pressure is a research topic. Over the lifetime, 5142 publications have been published within this topic receiving 30717 citations.
Papers published on a yearly basis
1 / 3
Papers
Patent•
3 Feb 1997
TL;DR: In this paper, a three way valve controlled by the circuit connected the duct transducer to gas metered to the cavity is used to determine the rate of pressure change after the valve connection.
Abstract: A method and apparatus detect occlusion in a tube to a passage into a body cavity. An argon gas supply output received by plural selectable flow orifices so one or more of the orifices delivers predetermined metered gas. A duct with a volume of gas selectively provides metered gas to the passage. The tube connects the passage and the duct periodically so a duct pressure transducer can signal. A circuit tests signals of tube equalization with a back pressure. A three way valve controlled by the circuit connects the duct transducer to gas metered to the cavity. The valve alternatively connects the duct transducer to the tube to equalize the tube with metered gas to the back pressure. A monitor of the signals determines the rate of pressure change after the valve connection. The monitor indicates pressure equalization after a timed interval with a timer to establish intervals for checking back pressure. The monitor remembers cavity pressure before connecting the duct transducer to the metered gas and compares remembered pressure with the back pressure after each test interval. Plural orifices provide specific gas flows to the handset and the valve for equalizing them with metered gas as a function of the flow. Connecting plural orifices to meter gas output, delivering the metered gas output with one or more of the orifices, containing the volume of gas in the duct connected to the metered gas output, selectively connecting the duct to the passage, connecting the tube to the passage with the duct and the transducer to periodically signal are steps. Coupling the circuit to one or more orifices, equalizing the tube with back pressure in response to the signals and coupling the transducer to the metered gas output are steps. Connecting the duct transducer to the tube permits periodic back pressure equalization with metered gas output, signaling the monitor with the transducer, determining periodically the rate of pressure change in the tube by the transducer, indicating in the interval with the monitor equalized tube pressure and remembering cavity pressure before connecting the metered gas output and the transducer for intervals and providing specific flows to the handset and the valve to make the back pressure a function of the selectable flow are steps.
620 citations
1 Jan 2011
TL;DR: In this paper, the role of inlet stagnation pressure and back pressure on the performance of rotating-detonation-engines (RDEs) was investigated and it was found that the detonation wave height and mass flow rate are determined primarily by the stagnation pressure, whereas overall performance is closely tied to pressure ratio.
Abstract: Rotating-detonation-engines (RDE’s) represent an alternative to the extensively studied pulse-detonation-engines (PDE’s) for obtaining propulsion from the high efficiency detonation cycle. Since it has received considerably less attention, the general flow-field and effect of parameters such as stagnation conditions and back pressure on performance are less well understood than for PDE’s. In this article we describe results from time-accurate calculations of RDE’s using algorithms that have successfully been used for PDE simulations previously. Results are obtained for stoichiometric hydrogen–air RDE’s operating at a range of stagnation pressures and back pressures. Conditions within the chamber are described as well as inlet and outlet conditions and integrated quantities such as total mass flow, force, and specific impulse. Further computations examine the role of inlet stagnation pressure and back pressure on detonation characteristics and engine performance. The pressure ratio is varied between 2.5 and 20 by varying both stagnation and back pressure to isolate controlling factors for the detonation and performance characteristics. It is found that the detonation wave height and mass flow rate are determined primarily by the stagnation pressure, whereas overall performance is closely tied to pressure ratio. Specific impulses are calculated for all cases and range from 2872 to 5511 s, and are lowest for pressure ratios below 4. The reason for performance loss is shown to be associated with the secondary shock wave structure that sets up in the expansion portion of the RDE, which strongly effects the flow at low pressure ratios. Expansion to supersonic flow behind the detonation front in RDE’s with higher pressure ratios isolate the detonation section of the RDE and thus limit the effect of back pressure on the detonation characteristics.
327 citations
1 Jul 2007
TL;DR: In this paper, it was shown that power augmentation is proportional to the mass flow increase generated at the nozzle of the DAWT, such mass flow augmentation can be achieved through two basic principles: increase in the diffuser exit ratio and/or decreasing the negative back pressure at the exit.
Abstract: History of the development of DAWT's stretches a period of more than 50 years. So far without any commercial success. In the initial years of development the conversion process was not understood very well. Experimentalists strived at maximising the pressure drop over the rotor disk, but lacked theoretical insight into optimising the performance. Increasing the diffuser area as well as the negative back pressure at the diffuser exit was found profitable in the experiments. Claims were made that performance augmentations with a factor of 4 or more were feasible, but these claims were not confirmed experimentally. With a simple momentum theory, developed along the lines of momentum theory for bare windturbines, it was shown that power augmentation is proportional to the mass flow increase generated at the nozzle of the DAWT. Such mass flow augmentation can be achieved through two basic principles: increase in the diffuser exit ratio and/or by decreasing the negative back pressure at the exit. The theory predicts an optimal pressure drop of 8/9 equal to the pressure drop for bare windturbines independent from the mass flow augmentation obtained. The maximum amount of energy that can be extracted per unit of volume with a DAWT is also the same as for a bare wind turbine. Performance predictions with this theory show good agreement with a CFD calculation. Comparison with a large amount of experimental data found in literature shows that in practice power augmentation factors above 3 have never been achieved. Referred to rotor power coefficients values of CP,rotor =2.5 might be achievable according to theory, but to the cost of fairly large diffuser area ratio's, typically values of β >4.5.
232 citations
TL;DR: In this paper, a regenerative organic Rankine cycle (ORC) was used to utilize the solar energy over a low temperature range and a thermal storage system was employed to store the collected solar energy and provide continuous power output when solar radiation is insufficient.
227 citations
TL;DR: An improved genetic algorithm to optimize the highly nonlinear fuzzy control rules between the input and response in the fuzzy PID controller is designed, which significantly improves the performance of the wellhead back pressure control system.
193 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 2 |
| 2024 | 1 |
| 2023 | 15 |
| 2022 | 32 |
| 2021 | 62 |
| 2020 | 167 |