Methods and systems for operating an aircraft engine having a compressor are described. The method comprises determining, based on actual operating parameters of the aircraft engine, a compressor mass flow limit for an aerodynamic stability of the aircraft engine; determining an actual compressor mass flow of the compressor of the aircraft engine, wherein the actual compressor mass flow is based on measured values of the aircraft engine; comparing the actual compressor mass flow to the compressor mass flow limit; and governing operation of the aircraft engine to cause an alternative compressor mass flow when the actual compressor mass flow reaches or is anticipated to reach the compressor mass flow limit.

Repeated cycles each consist of a pump down phase and a holding phase, wherein a start timepoint of each cycle is the timepoint when a rise in an inlet pressure of the pump is sufficiently large and the time extending between two consecutive cycle start timepoints is a cycle time. A control method includes determining a start of a next cycle during a present cycle, wherein it is preferable that the present cycle directly precedes the next cycle. The method further includes controlling the pump to accelerate to a maximum allowed speed during the holding phase of the present cycle before the start of the next cycle such that at the start of the next cycle full pump capacity is available.

A hydrogen dispensing system includes a hydrogen storage tank for storing hydrogen gas, a turboexpander generator fluidly connected to the hydrogen storage tank, and a dispenser fluidly connected to the turboexpander generator. The turboexpander generator receives a flow of the hydrogen gas from the hydrogen storage tank at an inlet of the turboexpander generator, reduces a pressure and a temperature of the flow of hydrogen gas, and outputs the hydrogen gas to the dispenser.

The disclosure includes controlling a pressure ratio for a compressing system, comprising introducing a quantity of liquid into an input stream to create a multiphase input stream, compressing the multiphase input stream with a centrifugal compressor to create a discharge stream, measuring a parameter of the discharge stream, wherein the discharge parameter corresponds to a pressure ratio for the centrifugal compressor, when the parameter exceeds a first predetermined point, increasing a pressure ratio of the centrifugal compressor by increasing the quantity of liquid introduced, and when the parameter exceeds a second predetermined point, decreasing the pressure ratio by decreasing the quantity of liquid introduced.

A method for determining a mass flow of a dynamic compressor that does not include a mass flow sensor while the compressor is operating to compress a working fluid includes determining, by a processor, a current operating point of the compressor. If the current operating point is the same as one in a map of a plurality of predetermined operating points stored in a memory, the mass flow of that predetermined operating point is retrieved as the mass flow of the current operating point. Otherwise, the processor calculates the mass flow at the current operating point from the mass flows of a subset of the predetermined operating points nearest the current operating point. The dynamic compressor continues to operate to compress the working fluid based at least in part on the calculated mass flow rate for the current operating point.

Smart fans are described that can be used in any application in which a flow of a fluid, such as air, is required. In one application, a blower door panel is provided that may include a fan or smart fan. The blower door panel includes an air impermeable membrane and a frame secured to the air impermeable membrane. The frame includes a plurality of frame members, and at least one of the frame members includes a first frame portion and a second frame portion, in which the first frame portion and the second frame portion are slidably attached to each other to allow the first frame portion and the second frame portion to longitudinally slide relative to one another between a collapsed configuration. The frame member includes a one-way self-locking length controller that selectively controls relative longitudinal movements between the first frame portion and the second frame portion.

Control system arranged for a rotary compressor driven by a rotary engine, and includes: a first control subsystem, a second control subsystem and a selector; the first control subsystem is arranged to provide a first control signal as a function of the performance and the speed of the compressor; the second control subsystem is arranged to provide a second control signal as a function of the performance of the compressor; the selector is arranged to select the first control signal or the second control signal as a third control signal to be provided to a power control input of the engine.

Control system arranged for a rotary compressor driven by a rotary engine, and includes: a first control subsystem, a second control subsystem and a selector; the first control subsystem is arranged to provide a first control signal as a function of the performance of the compressor; the second control subsystem is arranged to provide a second control signal as a function of the speed of the compressor; the selector is arranged to select the first control signal or the second control signal as a third control signal to be provided to a power control input of the engine.

Herein provided are methods and systems for controlling an engine having a variable geometry mechanism. A pressure ratio between a first pressure at an inlet of the engine and a predetermined reference pressure is determined. An output power for the engine is determined. The output power is adjusted based at least in part on the pressure ratio to obtain a corrected output power. A position control signal for a variable geometry mechanism of the engine is generated based on the corrected output power and the pressure ratio. The position control signal is output to a controller of the engine to control the variable geometry mechanism.

The disclosure includes controlling a pressure ratio for a compressing system, comprising introducing a quantity of liquid into an input stream to create a multiphase input stream, compressing the multiphase input stream with a centrifugal compressor to create a discharge stream, measuring a parameter of the discharge stream, wherein the discharge parameter corresponds to a pressure ratio for the centrifugal compressor, when the parameter exceeds a first predetermined point, increasing a pressure ratio of the centrifugal compressor by increasing the quantity of liquid introduced, and when the parameter exceeds a second predetermined point, decreasing the pressure ratio by decreasing the quantity of liquid introduced.