Eliphas Wagner Simões, Rogerio Furlan, Roberto Eduardo Bruzetti Leminski, Mário Ricardo Gongora-Rubio, Marcos Tadeu Pereira, Nilton Itiro Morimoto
Micro fluidic oscillators were obtained from wall attachment micro fluidic amplifiers using a feedback loop from the outputs to the control inputs. These devices can be used as actuators, as mixers, and also as flow meters, when the oscillation frequency is proportional to the volumetric flow in subsonic and moderately compressible conditions. The devices were then made in a SU-8 based epoxy photo resist using photolithography ultraviolet process. The article shows the results obtained in the experimental tests of the devices with gases (nitrogen, argon, and carbon dioxide). The dimensions...
Jiun-Jih J. Miau, Chen-Fan Yeh, Chih-Chung Hu, Jung-Hua Chou
Measurement uncertainty of a T-shaped flowmeter was examined with a gas flow calibration facility, for Reynolds numbers, Re d , in a range of 2.56 × 10 4 - 1.56 × 10 5 . The total uncertainty interval of the Strouhal values deduced from a Fourier spectral analysis was ±0.745 %, and the linearity of the data was ±1.78 %. Meanwhile, a scheme based on pulses counting in reference to the analog signals measured gave the total uncertainty interval of the meter factor as ±0.568 %, with the linearity ±1.89 %.
Ernst von Lavante, Udo Banaszak
In the present investigation, the problem of accurate determination of volumetric flows by means of the so-called vortex-shedding flowmeter in the case of shape changes from the original specifications due to wear was studied. To this end, the flow about the bluff body used in the presently studied vortex-shedding flow meter was numerically simulated using a solver of the unsteady, compressible Navier-Stokes equations in two and three dimensions. The computations were carried out for several Reynolds numbers using modified geometry in which rounded edges representing wear were introduced....
Oliver Ricken, Volker Hans
In vortex-shedding metering not only the shape of a bluff body is important but also the angle of incidence of the bluff body plays a major role in connection with production tolerances and unsymmetrical inflow. In the present investigation the influence of different angles of incidence of bluff bodies on the measured vortex frequency and the flow around the bluff body was studied by using ultrasonic barriers and rectangular and triangular shapes with 1:1 ratio of width to length for the bluff body. It became apparent that the vortices separate at different edges by inclination of the bluff...
Yaoying Lin, Volker Hans
This paper studies a factor which might influence the Strouhal number, that is, the inclination of the bluff body. The inclination of the bluff body happens in flow industry when the bluff body is inclined relative to its pipe parallel axis. Triangular bluff bodies are thoroughly discussed in this paper. Normally, the flat side is facing the inflow which is called conventional setup. It is turned around with 180 degrees facing the sharp side to the inflow, which is called unconventional setup in this paper. The inclination of bluff body has different influences in each setup. This paper...
Wen Hanhang
The ISO 9300 Critical Flow Venturi Nozzle can be operated properly only in critical flow. If critical flow is not obtained, either a wrong measurement results, or the measurement is stopped if U > U kp is confirmed. In addition, the measuring range of the Venturi nozzle is limited by the working pressure of the air source, therefore, the range of the measurement is small. Per the ISO 9300 standard, the critical flow Venturi nozzle is transformed into a critical-flow-subsonic Venturi nozzle with function of taking pressure on the throat. A high accurate differential pressure convertor and the...
Lei Lin, Li Ning, Wang Hou-Jun
Without actual flow standard equipment of certain type of flow media or on the occasion of requiring no high measuring accuracy, critical flow coefficient of Venturi nozzle may be disposed by other methods instead of being actual flow calibrated through this flow media. The flow coefficient calibrated by other media, being enough analyzed and computed can be directly applied to a flow measurement of the other media. This article mainly researches on conversion method and analysis and computation of uncertainty of critical flow coefficient when Venturin nozzle works in critical flow state. In...
E. von Lavante, B. Mickan, R. Kramer
Several Venturi nozzles, operating at critical conditions and shaped according to the recommendations of the ISO Standard 9300 were selected for the present study. The flow in the nozzles was investigated numerically for a range of Reynolds numbers. The present results were compared with experimental data where available. The unsteady compressible viscous flow in the nozzles was simulated using the Navier-Stokes solver ACHIEVE, developed by the first author. Several models for predicting the laminar-turbulent transition were tested. Significant phenomena associated with the transition were...
Jae-Hyung Kim, Heuy-Dong Kim, Kyung-Am Park
Recently, critical nozzles have been extensively utilized to measure the mass flow rate in a variety of industrial applications. For the measurement of the mass flow rates at a wide range of operation conditions, the critical nozzle is required to be designed with different diameters. The objective of the present study is to investigate the effectiveness of a variable critical nozzle. A rod with a small diameter is inserted into the critical nozzle to change the effective cross-sectional area of the critical nozzle. Experimental work is performed to measure the mass flow rate of the critical...
Bodo Mickan, Rainer Kramer, Petra Kiesewetter, Dietrich Dopheide
The paper presents a new approach for the determination of discharge coefficients of sonic nozzles. Innovating the conventional way, where the knowledge of throat diameter is always necessary, the new approach utilises a special mathematical characteristic of the equation c D = a + b · Re -0.5 to figure out a relationship of the parameter b as a function of the parameter a and to define a new parameter β with b = f ( a , β ). It is shown in the paper by theory as well as by experimental results, that the parameter β can be determined only from measurements of flow rate and gas parameters...