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Using the torque characteristics of dampers to measure airflow. 1. Model development and validation. 2. Analysis and testing.

Author(s) : FEDERSPIEL C.

Type of article: Article

Summary

Part 1 of the paper describes the development of a mathematical model for predicting the aerodynamic torque characteristics of dampers. The model relates position, velocity, and aerodynamic torque so that one of the three can be estimated if the other two are known. The model is based on the theory of free streamlines. The accuracy of the model was tested experimentally. A wind tunnel equipped with a five-point pitot tube array was used to test the torque characteristics of a damper with an offset-blade construction. The model was calibrated with one data set and tested with a second. The experimental results demonstrate that the model accurately predicts torque characteristics over a wide range of operating conditions. Part 2 of the paper describes the analysis and testing of a method of measuring airflow from position and torque (APT) measurements of dampers. The method is based on a newly developed mathematical model of the aerodynamic torque characteristics of dampers. An uncertainty analysis demonstrates that the APT method can outperform a pitot tube over a wide range of conditions, but that it cannot outperform a pitot tube when the damper is nearly open. Tests on an off-set blade damper and a commercially available airflow station confirm the results of the uncertainty analysis and demonstrate that the APT technology is also insensitive to upstream airflow disturbances when the damper is less than 70% open.

Details

  • Original title: Using the torque characteristics of dampers to measure airflow. 1. Model development and validation. 2. Analysis and testing.
  • Record ID : 2004-1065
  • Languages: English
  • Source: HVAC&R Research - vol. 10 - n. 1
  • Publication date: 2004/01
  • Document available for consultation in the library of the IIR headquarters only.

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