Application Cases

Experimental Name: Distribution Patterns of Scattered Sound Fields and Measurement Techniques for Gas-Liquid Two-Phase Flow in Combustion Chambers

Research Focus: Scattered Sound Fields

Experimental Content:
By using a high-voltage amplifier to drive an ultrasonic transducer, ultrasonic waves are incident into the combustion chamber, and changes in the scattered sound field caused by scatterers within the chamber are measured. Through in-depth analysis of the relevant scattered sound field, the measurement of gas-liquid two-phase flow parameters in the combustion chamber is further achieved.

Test Equipment: ATA-2082 high-voltage amplifier, ultrasonic transducer, ultrasonic generator, data acquisition card, etc.

Figure 1: Experimental Setup

Experimental Process:
The ultrasonic signal is amplified by a high-voltage amplifier and then input to an ultrasonic transducer to generate ultrasonic waves within the combustion chamber. Ultrasonic signals are collected via an ultrasonic microphone. The experiment is divided into two main parts:

1. Measurement of the Scattered Sound Field in the Combustion Chamber: Due to the high-temperature and high-pressure environment inside the combustion chamber, measurement holes need to be drilled. The influence of the pressure measurement holes on the ultrasonic signals was first investigated. Further studies were conducted on extracting scattered signals and measuring the distribution patterns of the scattered sound field under the harsh conditions of the combustion chamber.

2. Measurement of Gas-Liquid Two-Phase Flow Parameters in the Combustion Chamber: The primary measurement target selected was a deionized water jet. A high-speed camera and an ultrasonic receiver were used to collect changes in the images and scattered sound field information caused by the deionized water jet, respectively. Through subsequent data processing, measurement of the gas-liquid interface of the jet was achieved.

Test Results:

The experiment was divided into two parts:

• First, the influence of pressure measurement holes on ultrasonic signals was studied, focusing on the effects of hole depth and diameter. The results are shown in Figure 3. Acoustic energy was extracted from the measured pulsed scattered waves to further study the distribution of the scattered sound field. The measurement results of the scattered sound field are shown in Figure 4.

• Second, the measurement of gas-liquid two-phase flow parameters was conducted. An ultrasonic measurement method was used to achieve measurement of the gas-liquid two-phase flow interface in the combustion chamber. The final temporal resolution reached 1 kHz, and the spatial resolution reached the hundred-micron level. Using image measurement results as a reference, the maximum error of the ultrasonic measurement was within 200 µm, the maximum relative measurement error did not exceed 10%, and the average relative error was 3.5%. This work, for the first time, achieved high-frequency and high-precision measurement of the gas-liquid two-phase flow interface in a combustion chamber using an ultrasonic measurement method, developing a new flow visualization technique in gaseous environments.

Power Amplifier Recommendation: ATA-2082 High-Voltage Amplifier

Figure: ATA-2082 High-Voltage Amplifier Specifications and Parameters

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