Miniature total pressure probe and preparation method thereof
Technical field
What the present invention relates to is a kind of being used for to belong to the flow field survey technical equipment at miniature total pressure probe of flow field gaging pressure and preparation method thereof.
Background technology
Obtained in recent years on the basis of develop rapidly in microelectromechanical systems (MEMS), aerospace field has occurred such as minute vehicle, miniature turbine engine, micromachines such as micro-satellite and microrocket.Carry out the technical works such as research and development that these relate to the various miniaturized devices of fluid motion, need carry out corresponding microscale flow field experimental study.
Current considerable microscale flows characteristic dimension especially in millimeter and centimetre magnitude, and the microfluidic of this grade also lacks effective experiment measuring means at present.Up to now, the pressure reduction that passage is imported and exported has just been measured in domestic and international most microfluidic experiment, what take this to obtain only is the average friction drag characteristic that microscale flows, can't learn along journey distribution and its result inevitably to comprise the import and export flow losses, so measurement result is careful inadequately, accurate.Adopt molecule tracking velocity measuring technique (MTV) and particulate image velocity measuring technique (M-PIV) can obtain detailed flow field velocity distributed intelligence, but because this kind equipment costs an arm and a leg (being worth more than millions of yuans), the operation technique complexity, therefore use and limited to, generally be used for the experiment measuring of micron order microfluidic.
Summary of the invention
A kind of miniature total pressure probe that is used at the flow field gaging pressure that the present invention proposes, be intended to develop the routine measurement means, for the flow field of characteristic dimension in millimeter and centimetre-sized, utilize miniature total pressure probe to measure, obtain the details that microscale flow field stagnation pressure (flow velocity) distributes, can guarantee that again miniature total pressure probe intensity can bear microscale low reynolds number air-flow and act on the load of probe and do not influence miniature total pressure probe rigidity.
Technical solution of the present invention: miniature total pressure probe, its structure are to have three grades of external diameters, and stepped appearance pipe, end of probe external diameter are 0.2mm, and three grades length ratio is 1: (3~5): (8~12) are 1: 2: 5 corresponding to the external diameter ratio of three level lengths.
The method for making of miniature total pressure probe, its processing step branch (one) fine electric spark processing technology; (2) pure water micro-electrochemical machining processing technology; (3) microoperation technology.
Described fine electric spark processing technology step (one) is in edm process, and by pipe is carried out pulsed discharge, electric spark causes the removal of material micelle and the generation in discharge hole, thereby forms the two-stage stepped appearance pipe of above-mentioned pipe 1/2 external diameter.
Described pure water micro-electrochemical machining processing technology step (two) is as the instrument anode with above-mentioned two-stage stepped appearance pipe, one metal plate is as tool cathode, adopt pure water as working fluid, extra electric field polishes the pipe end face rapidly, avoids because the end face edge ablation that dispersion corrosion causes, guarantee the clear angle of clear rib, adopt the reinforced conductive connecting process, guarantee the airtight and processibility of part, obtained first and second two-stage stepped appearance pipe of miniature total pressure probe like this.
Described microoperation processing step (three) is to be that the hollow circular-tube of five times of head outer diameter is enclosed within the two-stage stepped appearance pipe outside that above-mentioned processing step obtains by mini positioning platform system, microoperation mechanical arm, micro-image and autofocus system with an external diameter, is guaranteeing that the back adopts cementing agent that these two pipes are bonded together to obtain the miniature total pressure probe of three grades of stepped appearance pipes with one heart.
Advantage of the present invention: for the microfluid Experiments of Machanics provide effective measurement means, the miniature total pressure probe design of three grades of stairsteppings both can guarantee effectively to measure yardstick and distribute at the flow field of millimeter and centimetre-sized stagnation pressure, can guarantee that again miniature total pressure probe intensity can bear the load that microscale low reynolds number air-flow acts on probe, and not influence miniature total pressure probe rigidity.Miniature total pressure probe cost of the present invention is low, easy to use, economic and reliable.Adopt fine electric spark and micro-electrochemical machining complex machining process, entire making process adopts a clamping, and bearing accuracy reaches 2 μ m; Adopt the alternating-current pulse power technology in the process, guarantee lower processing roughness; Adopt pure water micro-electrochemical machining processing technology, realize the end face polishing, reduced machined surface roughness, adopt the reinforced conductive connecting process, guarantee the airtight and processibility of part, adopt microoperation technology, guarantee the technical requirement of assembling.
Description of drawings
Accompanying drawing is a miniature total pressure probe example structure synoptic diagram,
A1 among the figure, A2, A3 are the root positions of three pipes, and L1, L2, L3 are respectively the length of three pipes.
Embodiment
Embodiment 1,2,3, uniformly distributed load on three pipeline sections, and three external diameter of pipe of the length L 1 of three pipes, L2, L3 correspondence are D1, D2, D3.
Its structure is that miniature total pressure probe has three grades of external diameters, stepped appearance pipe step by step, and head outer diameter is 0.2mm, the outer diameter D 1 of three pipes, D2, D3 are respectively 0.2mm, 0.4mm, 1mm;
The length of three pipes: wherein length L 1, L2, the L3 of three pipes among the embodiment 1 are respectively 2mm, 6mm, 16mm.
Length L 1, L2, the L3 of three pipes among the embodiment 2 are respectively 2mm, 8mm, 20mm.
Length L 1, L2, the L3 of three pipes among the embodiment 3 are respectively 2mm, 10mm, 24mm.
The method for making of miniature total pressure probe
Fine electric spark processing technology step (one) is in edm process, carry out pulsed discharge by pipe to external diameter 0.4mm, electric spark causes the removal of material micelle and the generation in discharge hole, thereby forms the two-stage stepped appearance pipe of first order external diameter 0.2mm, second level external diameter 0.4mm.
Pure water micro-electrochemical machining processing technology step (two) is as the instrument anode with above-mentioned two-stage stepped appearance pipe, one metal plate is as tool cathode, adopt pure water as working fluid, extra electric field polishes the pipe end face rapidly, avoids because the end face edge ablation that dispersion corrosion causes, guarantee the clear angle of clear rib, adopt the reinforced conductive connecting process, guarantee the airtight and processibility of part, obtained first and second two-stage stepped appearance pipe of miniature total pressure probe behind glossing like this.
Microoperation technology is that (microscope adopts the 12X microscope of Navitar company by mini positioning platform system (the M-415.PD type assembling of German PI company), microoperation mechanical arm (the MP285 type of U.S. Sutter company), micro-image and autofocus system, CCD adopts the UM201 of U.S. UNIQ company, image acquisition processing card adopts the Genesis system card of Canadian Matrox company, the selectivity autofocus system, realize that by the motion in one dimension platform platform adopts the M126.DG of German PI company) form little assembly system.Can assemble the micro parts of size in microscale (1 μ m-100 μ m) and mesoscale (100 μ m-1 μ m) scope.This technology is that the hollow circular-tube with one section external diameter 1mm, internal diameter 0.5mm is enclosed within the two-stage stepped appearance pipe outside that previous process obtains, and is that 0.2mm, second level external diameter are that 0.4mm, third level external diameter are three grades of step-like miniature total pressure probes of 1mm guaranteeing that with one heart the back adopts cementing agent to bond together these two pipes to obtain first order external diameter.
Table 1 is intensity, the rigidity estimation result of total pressure probe.
Table 2 is the result of calculation of miniature total pressure probe maximum defluxion, and therefrom combined deflection meets the demands all less than 1% of each pipe range as can be seen.
The intensity of table 1 total pressure probe, rigidity estimation result
Each manages size relationship | D
3=2.5D
2=5D
1,L
3=2L
2=10L
1 |
Checkschema | Independent calibrated tube 1 | Count pipe 2 | Count pipe 3 |
Strength condition mm | L
1≤6.26
| L
1≤2.77,L
2≤11.06
| L
1≤2.56,L
2≤10.24,L
3≤25.6
|
Rigidity condition mm | L
1≤7.78
| L
1≤3.37,L
2≤13.5
| L
1≤2.81,L
2≤11.24,L
3≤28.1
|
Table 2 miniature total pressure probe maximum defluxion result of calculation (mm of unit)
| The maximum defluxion that uniformly distributed load produces | The maximum defluxion that the equivalence transversal force produces | The maximum defluxion that equivalent moment produces | The maximum defluxion that the resultant action effect produces | 1% of each pipe range |
Pipe 1 | 0.00034 | - | - | 0.00034 | 0.02 |
Pipe 2 | 0.01086 | 0.00362 | 0.00068 | 0.01516 | 0.08 |
Pipe 3 | 0.02722 | 0.01300 | 0.00446 | 0.04468 | 0.20 |
These calculate the stand under load of being analyzed by prior art is the result who supposes under the vertical condition with air-flow of probe, and can be greater than 10~15 degree with the angle of air-flow in the actual use of miniature total pressure probe of the present invention, actual load ratio is calculated little 1~2 order of magnitude of load of hypothesis.Therefore, such design proposal can guarantee can not influence because of distortion the accuracy of measurement.