SU139936A1 - Device for measuring aerodynamic parameters of helicopter rotors - Google Patents

Description

Devices are known for measuring the aerodynamic parameters of helicopter rotors, made in the form of electrical dynamometers and electronic self-balancing bridges.

However, the measurement error from very low frequency electrical noise from these devices is high.

A distinctive feature of the described device is that the suppression of the transducer components of the measured electrical signals is carried out by introducing into the measurement and amplifying unit an electronic automatic feedback bridge in the form of an electromechanical compensator, which provides a variable electric signal proportional to the input signal. measuring electrical signal and with the latter in prostisophase.

Such a device with an electromechanical compensator made in the form of a low-inertia engine with three coils, one of which reciprocates and interacts with a beam carrying a pressure sensing bridge, improves the accuracy of measurement of aerodynamic parameters and compensates infra-frequency electrical signals in the measuring circuit.

FIG. 1 is a schematic diagram of the device; in fig. 2 - sectional electromechanical compensator; in fig. 3 - schematic diagram of an electromechanical compensator.

A measuring bridge, consisting of strain gauges 1, 2, 3, and 4, glued onto elastic elements of electric dynamometers, and a power source 1, is electrically connected to a compensation bridge, strain gauges; whose sensors 5, 7, and 8 are powered by source 2 current, pasted on lightweight duralumin beams 9, interacting with the item № 139936-2

coil 10, reciprocatingly moving in opposite-connected coils and 12 low-inertia engine 13.

The measuring and compensating bridges electrically interact through amplifiers 14, 15, and 16 of voltage, power, and direct current-With a reversible motor 17, the axis of which is connected to the moving contact of the reichord 18 and the reading device 19. Aerodynamic forces by means of elastic elements of dynamometers using strain sensors 1 2, 3, and 4 are converted into a measured electrical signal, balanced by a reversible motor / 7 and reichord J8.

Electrical signals with a frequency greater than that of the measured one are balanced by a compensated bridge (electromechanical compensator).

The voltage taken from the measuring bridge, passed through the input filter, is modulated by the input device of the M voltage amplifier with a frequency of 50 Hz and is amplified by it. With the amplifier M, the voltage is applied to the power amplifier 15 and to the DC amplifier J6, which includes a demodulator, a filter, and a phase-shifting chain. With the amplifier, the voltage is applied to the reversing motor 17, which interacts with the reohord and the readout device.

From the smoothed, demodulated voltage supplied to the DC amplifier 16, is extracted by means of an infra-low-frequency envelope transformer, which is fed to the moving coil W of a low-inertia motor. The coil W deforms the duralumin beam 9. Strain gauges 5, 6, 7 and 8 transform the deformation of the beams into electrical voltage, which is fed into the measuring circuit in antiphase. This is used to compensate the signal in the measuring circuit at an infra-low frequency. Thus, the DC voltage signal is measured by the self-balancing bridge method, and the infra-low frequency electrical signal is balanced by a compensated bridge, which allows it to be compensated in the measuring circuit without introducing an error in the measured DC voltage signal.

At the conclusion of TsAGI, the proposed device was recognized as industrially useful.

Subject invention

Claims (2)

1. A device for measuring aerodynamic parameters of helicopter rotors, made in the form of electronic self-balancing bridges, characterized in that, in order to increase the accuracy of measuring aerodynamic pairs and meters in the measuring circuit of the electrical signals of the infrared frequency, the electronic automatic measuring unit The bridge has feedback in the form of an electromechanical compensator. 2. A device according to claim 1, characterized in that the electromechanical compensator is made in the form of a low-inertia engine with three coils, one of which reciprocates and interacts with the beam carrying the compensating tensor-metric bridge. 12 U