Gas flow area measurement
AssigneeStandard Aero Limited
InventorEduardo R Evangelista
Life of this patent
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Abstract
The effective flow area of a restriction in a gas flow passage, such as that of a gas turbine nozzle or vane, is determined by use of a large reservoir containing pressurized gas which is discharged through the passage in a blowdown operation in which the ratio of back pressure of the restriction to gas pressure in the reservoir is maintained below critical for sonic flow; a timer may be used to measure the time for a predetermined fall of pressure in the reservoir whilst there is sonic flow through the restriction.
Claims29
Method for determining the effective flow area of a restriction in a gas flow passage, said method comprising the steps of:
- providing a gas reservoir,
- providing a flow control means,
- arranging a restriction in communication with a controlled flow of gas flowing from said reservoir through the flow control means, and
- operating the flow control means to allow a transient sonic flow of pressurised gas through the restriction from the reservoir,
- wherein the sonic flow is sustained temporarily at the restriction, as a mass flow rate is allowed to diminish rapidly with rapid decrease in reservoir temperature and pressure, by maintaining the ratio of the back pressure of the restriction to the gas pressure in the reservoir below critical.
Apparatus for determining the effective flow area of a restriction in a gas flow passage comprising:
- a reservoir,
- a means for communicating a restriction with the reservoir, a flow control means operable to control a transient sonic flow of pressurized gas through the restriction from the reservoir to allow sonic flow to be sustained temporarily at the restriction
- a pressure sensing means to respond or provide a signal related to the pressure of gas in the reservoir,
- a temperature sensing means for providing a signal related to the temperature of the gas in the reservoir,
- a timer means operable to provide a signal related to the duration of flow of gas through the restriction, and
- a processing means programmed to derive a measurement related to the effective flow area of the restriction by processing signals from the pressure sensing means, the temperature sensing means, and the timer means.
Dependencies are inferred from the claim text.