Keyvisual: VTflX - Variable Venturi Tube

VTflX – Variable Venturi Tube

For flow measurement of compressor intake air

How it works

The VTflX is a high-precision measuring device for measuring the flow of compressor intake air of the turbocharger on the hot gas test bench. The measuring device operates according to the differential pressure principle and is designed as a variable Venturi tube.

The differential pressure principle is based on the static pressure difference that occurs when the flow passes through a defined constriction. The mass flow is determined from the absolute static pressure at the inlet, the static pressure in the narrowest cross-section, and the temperature.

The measurement uncertainty over the entire calibrated measuring range is less than 0,5%. An initial calibration is carried out on a certified calibration test bench (Swiss Federal Institute of Metrology, METAS). The measured values are traceable via the calibration institute to internationally supported implementations of the SI units. The measured value processing, the calculation of the characteristic quantities and the output of the characteristic quantities are carried out in the automation system PAtools TX.

System benefits

The advantages of the VTflX are a large measuring range (1:50), high accuracy and precision and resistance to contamination of the intake air. The VTflX is based on the technically proven Venturi principle, is mechanically robust and compact and can be easily integrated into the hot gas test bench.

The measuring system we developed is  equal in robustness, accuracy, and repeatability than standard flow orifices. This measurement range (1:50) covers the requirements of radial compressors during turbocharger mapping very well. Internal comparisons with thermal or ultrasonic-based measurement systems show that our VTflX measurement device has clear advantages in terms of dynamic, raw signal stability, and accuracy.

The improved long-term stability compared to other volume flow measurement systems enables increased test bench availability in daily operation, while at the same time reducing maintenance and calibration costs. Using the variable Venturi VTflX, the calibration needs are limited to the pressure and temperature probes and can be carried out on-site. Thus, the measurement device does not need to be returned to the manufacturer for calibration tasks.

Customer benefits

  • High accuracy
  • High reproducibility
  • High reliability
  • Suitable for dynamic measurements (t90<0.8s)
  • Detection of the surging process in the radial compressor
  • Robust design and insensitive to contamination
  • Easy calibration and adjustment of pressure and temperature sensors
  • Low maintenance requirements

Open to the future - VTflX provides potential beyond hot gas test benches

In the first step, the focus of design and functional implementation was on the application of turbocharger test benches and there especially on the compressor intake side. However, we clearly see the potential for applications beyond hot gas test benches. There are advantages for all testing tasks and implementation where high demands on accuracy and repeatability occur. For example, this applies to component test benches (fuel cells, flow benches for cylinder heads, etc.) and additionally as a reference for engine air intake charge determination models on engine test benches.

Test it - with our demo device

The new series is already in daily use and some of the devices have now completed operating times of more than 3000 hours without significant wear or loss of accuracy. All systems in use have been calibrated at the Swiss Federal Institute of Metrology (METAS).
We have one of the devices ready for you as a demo device. We would be pleased to make this VTflX available to you for a test run.

Interested? Please get in contact with us!

We are happy to help!


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