Flow measurement method in non-uniform flow profiles

Abstract

The invention relates to a method that determines the probe parameters required for flow measurement in non-uniform flow profiles and enables probe design accordingly.

Description

[0001] FLOW MEASUREMENT METHOD IN NON-UNIFORM FLOW PROFILES

[0002] Technical Field of the Invention

[0003] The invention relates to a method that determines the probe parameters required for flow measurement in non-uniform flow profiles and enables probe design accordingly.

[0004] State of the Art

[0005] Flow measurement for flow profiles is done using a flowmeter or probe. In cases where the flow profile is complex, proper positioning of the measurement probe is very difficult, so proper measurements cannot be taken. Therefore, the use of flow meters is preferred for these cases.

[0006] Flow meters basically calculate the flow rate by measuring the pressure at the inlet and outlet planes of the flow passing through a narrow area called the orifice. Another method is to use a fin system in flow meters.

[0007] In the state of the art, the prices of flow meters used for flow measurement in complex flow profiles are very high. In addition, the risk of failure is high, especially when connected to a test device where vibration is expected or comprises particles (dust, dirt) therein. In the measurement method with a probe, since the flow is not smooth, the correct position of the probe cannot be found, which makes it very difficult to take correct measurements.

[0008] The invention that is the subject of the application numbered “US5675259A” in the state of the art relates to methods and apparatus for monitoring the presence, concentration and movement of fluids. More particularly, said invention relates to instrumentation and techniques for using electromagnetic measurements of complex permeability to detect and monitor the behaviour of fluids, including measuring instantaneous changes in the flow conditions of multiple fluids in a flow line or two or more states of a single fluid.

[0009] In the invention that is the subject of the application numbered “EP570052A2” in the state of the art, a method for measuring the flow rate of a continuous phase in a flowing multiphase fluid including measuring the speed of the fluid by thermal anemometry at a location in the flow and simultaneously measuring the transition of a discontinuous phase at the same location using a local probe system is described.

[0010] The state of the art includes the use of probes to measure flow rates. However, there is a need for a method that enables measuring flow rates using pressure probes in complex flow profiles and determines the probe parameters (e.g. probe aperture, number, position and angle) required for flow rate measurement in non-uniform flow profiles and enables probe design accordingly.

[0011] As a result, due to the negativities described above and the inadequacy of existing solutions on the subject, a new technology is needed in the relevant technical field.

[0012] Brief Description and Aims of the Invention

[0013] The invention relates to a method that determines the probe parameters required for flow measurement in non-uniform flow profiles and enables probe design accordingly.

[0014] The most important aim of the invention is to enable flow measurement using pressure probes in complex flow profiles. By means of these pressure probes, which are cheap compared to flow meters, it provides a large amount of savings in the required budget in test systems or applications where flow measurement is required.

[0015] Another aim of the invention is to eliminate problems such as the failure of flow meters due to particles such as dust and dirt entering them, their inability to be used in each test system, or the need for different flow meters for different fluids. With the invention, the necessary parameters can now be determined and standard probes can be used for flow measurement.

[0016] Description of Drawings

[0017] FIGURE 1-a is the drawing that shows the graph of the change in the error amount between the flow meter measurement and the probe method according to the probe range.

[0018] FIGURE 1-b is the drawing that shows the graph of the wall distance and probe range, which are the determined parameters. FIGURE 1-c is the drawing that shows the graph of the error amount of the measured velocity profile in m / s.

[0019] FIGURE 2 is the drawing that shows the first three steps of the zone elimination method of the method that is the subject of the invention. (The zones are numbered in clockwise order)

[0020] Detailed Description of the Invention

[0021] The invention relates to a method that determines the probe parameters required for flow measurement in non-uniform flow profiles and enables probe design accordingly.

[0022] Before starting the method, the parameters required for the method are defined and the 2-dimensional velocity profile on the plane to be measured is determined. The parameters required here are the probe numbers, probe spacings and the distance of the probe to the wall. The determined velocity profile is analysed to check whether the symmetry of the flow is achieved, and if there is symmetry, the next step is done according to the symmetry axis. This process is not mandatory for the method, but is used to speed up the process.

[0023] To determine the probe angle, the flow profile is divided into four equal parts and numbered 1 ,2,3,4. For the 1stand 2ndparts, an angle is determined to divide the region exactly in the middle and the flow rate calculation is made numerically as if a measurement was taken from a 5- or 3-point probe in the region. The calculation is compared with the actual result and the error margin is observed. The region with the highest error margin is deleted. The remaining parts are divided in half again with the appropriate angle and these parts are named as number 1 and 2. Then, the calculation is compared with the actual result and the error margin is observed. The region with the highest error margin is deleted and by repeating these steps, the region with the highest error margin is deleted again. The most suitable probe angle is found quickly as a result of statistical analysis by repeating these steps.

[0024] In order to determine the probe parameters, first the probe angle is determined. After that, the probe parameters are determined. The symmetric probe approach will be considered for the explanation here. First, the number of probes, probe diameter, closest wall distance, etc. limiting conditions are determined. (Limiting conditions should be determined separately according to the user's demand and the dimensions of the system to be measured.). The necessary calculations are made according to the determined limits and the appropriate probe geometry (probe diameter, number, etc.) is determined. The determined probe geometry is applied to the determined probe angle procedure and measurements are taken. Then, the controllable parameters are changed and parameter combinations are created. Calculations are made by applying new probe combinations to the determined angle and the probe with the most suitable parameters is determined.

[0025] A sample calculation was made using said method and compared with the actual measurement results made with the flow meter. All results are shown in Figure 1 . The change in the error amount between the flow meter measurement and the probe method according to the probe range is given in Figure 1 a. The graphof the wall distance and probe range, which are the determined parameters, is shown in Figure 1 b, and the error amount of the measured velocity profile in m / s is shown in Figure 1 c.

[0026] As a result of the study, the most suitable parameter with an error rate of 0.49% was determined between the use of the flow meter, which is expensive and risky to use in every environment, and the method that is the subject of the invention in Table 1 . Low- cost measurements can be made with a very low error value with the method that is the subject of the invention.

[0027] Table 1

[0028] The flow measurement method in non-uniform flow profiles comprises the following process steps; - Determining the two-dimensional velocity profile in the plane to be measured by numerical methods,

[0029] - Dividing the flow profile into four equal parts and numbering them clockwise

[0030] - Determining an angle to the first and second parts in a way that divides the region exactly in the middle and placing a symmetrical probe in the region and performing the flow calculation numerically by the processor using the total pressure,

[0031] - Comparing the actual result of the flow calculation with the calculation made and deleting the area with the high margin of error,

[0032] - Dividing the remaining parts in half again,

[0033] - Determining an angle for the first and second parts in a way that will divide the region exactly in the middle and performing the flow calculation numerically in the region, and finding the most suitable probe angle by repeating the process step,

[0034] - Determining the number of probes, probe diameter, closest wall distance and probe length limiting conditions by the user,

[0035] - Determining the appropriate probe geometry by the processor by performing geometric calculations on the probe according to the specified limits,

[0036] - T aking measurements by applying the determined probe geometry to the determined angle procedure and creating parameter combinations by changing the controllable parameters, and

[0037] - making calculations by the processor based on the total pressure and conservation equation by applying new probe combinations to the specified angle and determining the probe with the most suitable parameters.

[0038] In the process step where the processor determines the appropriate probe geometry by performing geometric calculations on the probe according to the determined limits; the maximum and minimum distance between the probes on the probe is calculated using the nearest wall distance.

Claims

CLAIMS1. Flow measurement method in non-uniform flow profiles, comprising the process steps of:- Determining the two-dimensional velocity profile in the plane to be measured by numerical methods,- Dividing the flow profile into four equal parts and numbering them clockwise- Determining an angle to the first and second parts in a way that divides the region exactly in the middle and placing a symmetrical probe in the region and performing the flow calculation numerically by the processor using the total pressure,- Comparing the actual result of the flow calculation with the calculation made by means of a processor and deleting the area with the high margin of error,- Dividing the remaining parts in half again,- Determining an angle for the first and second parts in a way that will divide the region exactly in the middle and performing the flow calculation numerically in the region, and finding the most suitable probe angle by repeating the process step,- Determining the number of probes, probe diameter, closest wall distance and probe length limiting conditions by the user,- Determining the appropriate probe geometry by the processor by performing geometric calculations on the probe according to the specified limits,- T aking measurements by applying the determined probe geometry to the determined angle procedure and creating parameter combinations by changing the controllable parameters, and- making calculations by the processor based on the total pressure and conservation equation by applying new probe combinations to the specified angle and determining the probe with the most suitable parameters.Flow measurement method in non-uniform flow profiles according to Claim 1 , wherein in the process step where the processor determines the appropriate probe geometry by performing geometric calculations on the probe according to the determined limits; the maximum and minimum distance between the probes on the probe is calculated using the nearest wall distance.

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