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Since the mid-1960s, scientists from the United States, Europe, and Japan have successively invested in fluid vibrating flowmeters in different ways. By the late 1960s and early 1970s, these three types of flowmeters had appeared one after another. The development of the three flowmeters is different due to manufacturing, application and promotion. The characteristics of vortex flowmeters have been fully demonstrated, being accepted earlier by users and being developed most rapidly. The development of the other two instruments is relatively slow, but this is gradually being promoted for several years.
In ancient times, people noticed that the wind can make different sounds from the tight strings. In the middle of the night, there was a record of the honking harp that was hung on the wall of the bedside and was awakened by the night wind. In the middle of the 16th century, the famous artist and scientist Leonardo da Vinci described in his works the whirlpool columns that appeared behind the bluff body in the water.
The first person in the world to study the phenomenon of vortex street was the Hungarian physicist Strouhal. In 1878, in his guided experiment, he discovered that under the influence of the wind, the pitch of a small string sound is proportional to the wind speed and inversely proportional to the diameter of the string.
In 1879, Rod Lalet (r. R. D. Deight) discovered that when a vortex causes a fluid to vibrate, the direction of vibration is perpendicular to the direction of flow; he also observes the natural pitch of the string and the tone of the wind acting on it. When coincided, the sound will suddenly increase.
In 1908, Benard pointed out that the periodicity of the wake behind the cylinder is related to the formation and arrangement of vortices.
In 1912, the German physicist Von. Kallnan studied the stability of vortex street based on a large number of experimental observations, and published the famous vortex street stability conditions in an infinitely uniform flow field. paper. The mathematical stability of the vortex street formed downstream of the cylinder is proved mathematically. Kaman's conclusion lays a theoretical foundation for the development and application of vortex flowmeters.
However, the main purpose of people's early research on vortex street phenomenon was to prevent disasters. With the development of industry, especially the development of the aviation industry, the destruction of vortex formation on production and building facilities was found, such as high-rise buildings, bridges, towers, port facilities, ship masts, cables, and drilling platform supports. It is destroyed in the storm. The destruction or breakage of the boiler piping, the header in the heat exchanger, and the temperature measuring tube in the pipeline are all related to the formation of the vortex street. Therefore, over a long period of time, scholars are observing and studying the regularity of vortex formation, exploring the causes of the destructive effects of vortex streets, and finding ways to prevent this destructive effect. In the middle of the 20th century, some scholars claimed that the struggle between mankind and vortexes has continued for nearly half a century.
There are always two sides to things. While some people are studying the role of preventing the destruction of vortex streets, others are discussing how to use vortex street phenomena and principles to do useful work and apply Kaman vortex street to measure fluid velocity. This is one of them. This idea was first seen in the 1935 U.S. patent. In the 1950s, American scientist Roshko proposed the possibility of applying Kaman vortex street to measure wind speed and conducted relevant experiments. In 1960, the test of the speed of a ship using the Kaman vortex street principle was carried out on the Japanese ship Shibo.
All of the above experimental studies were conducted under infinite two-dimensional uniform flow conditions. In the three-dimensional pipe flow field, the vortex street measurement flow was studied. It will be postponed until the mid-1960s. During this period, scientists from Japan, the United States, and the former Soviet Union have successively carried out research and development of vortex flowmeters.
In 1967, the Japanese scholars Tsuchiya Tsukiya and Yamazaki Kojiro studied the use of vortex street principle to measure the flow of a circular pipe. A cylindrical body was placed vertically in a circular pipe, and a metal flag that could rotate around a fixed axis was installed downstream of the cylindrical body. When the fluid flows, the vortex street causes the flag to oscillate from side to side to detect the vortex signal and carry out a flow measurement test.
In 1969, Yamazaki Koshiro and others studied the successful hot wire detection vortex flowmeter. The vortex generator used (hereinafter referred to as generator) is a cylinder. This result was finally introduced by Yokogawa Electric's commercialized vortex flowmeter. Almost at the same time, 'the United States East-ech company successfully developed the thermistor detection method vortex flowmeter, this type of flow meter uses a triangular column body, later introduced by the Japanese OVAL company.
These two kinds of instruments became the precursors of vortex flowmeters and were used in steel, petroleum and chemical industries. Its characteristics have attracted attention from all sides, and it also indicates to the world the bright future of vortex flowmeters.
In the 1970s, vortex flowmeters entered the period of rapid development, and various new detection methods and new products emerged in succession. In the 1970s, the new products of vortex flowmeters introduced by the instrument companies in various countries were roughly (West) House (Westing House) applying ultrasonic detection technology to launch ultrasonic vortex flowmeters;
(Japan) Beichen Motor Co., Ltd. applied strain detection technology to successfully develop a strain gauge vortex flowmeter;
(US) Eastech launched a second type of vortex flowmeter, vibrator-type vortex flowmeter that uses magnetoelectric detection technology.
(British) Kent Corporation uses capacitive detection technology and moment generators to provide users with capacitive vortex flowmeters;
(US) Ficher & Porter applies strain detection technology to dedicate enhanced strain vortex flowmeters to users;
(US) Foxboro Corporation adopts piezoelectric detection technology and uses T-shaped generators to push vortex flowmeters with piezoelectric elements and diaphragms as detection elements to the market (Japan) Yokogawa. Piezoelectric inspection technology and ladder generators, followed by hot wire vortex flowmeters, introduced the company's second vortex flowmeter product, a stress vortex flowmeter.
Into the 1980s, the development of vortex flowmeters was strong, new products continued to be introduced, and old products continued to improve.
(United States) Fishercont power 1 island company developed a dual-body stress vortex flowmeter;
(German) E+H company and (UK) Kent company applied piezoelectric detection technology, respectively, to successfully develop components for testing vortex flowmeters with interpolated components and rear-mounted components.
(United States) Rcher and Qiao ner company successfully launched dual-body and double-detection element stress type vortex flowmeter, and first provided dry calibration technical indicators to customers in the installation and use book;
(Japan) Tokyo Semiconductor Co., Ltd. successfully developed a photoelectric vortex flowmeter; by the late 1980s, the United States, Europe and Japan had about 10 companies producing vortex flowmeter products, according to relevant information. , 1987. The world's vortex flowmeter produced nearly 40,000 units.
An important milestone in the development of vortex flowmeters is that the standardization of products has received the attention of countries. The United States, Japan, Germany and other developed countries have successively formulated and promulgated their own vortex flowmeter product standards. In 1987, the United States increased the mechanical industry standard to the national standard AS plus the ANsl MFC' currency M-1987; in 1989, Japan issued the industrial standard JIS28766-1989; Germany also promulgated the vortex flowmeter product standard. Following the promulgation of standards in major countries, the International Organization for Standardization (ISOO) set out to develop an international standard for vortex flowmeters and published it in 1993 as a draft standard (Qiao 0/CD12764). These all mark the development, manufacture and application of vortex flowmeters into the standardization era.
Since the 1990s, the development of vortex flowmeters has made significant progress in the following areas:
(l) The basic technical work has been further developed. In Japan, research and test work on dry calibration of vortex flowmeters was carried out, and in-depth achievements were made. In order to reflect this success, they revised and supplemented the 1989 edition of the industry standard, adding to the impact of the size of the standard body and the dimensions of each part on the sensitivity of the Strouhal number and the impact of the vortex meter installation. . This is the new version of JISz8766:2(X)2.
(2) The digital signal processing technology has been developed in the direction of digitization. From the application of conventional active filters to the development of tracking filters, adaptive filtering and digital spectrum analysis applications, the precision, anti-interference ability and measurement range of vortex flowmeters have been improved.
(3) To the development of integration, intelligence, and multi-parameter detection, fieldbus technology is introduced into the vortex flow field. Fieldbus intelligent vortex flowmeters will become the fieldbus system (FCS). One of the important instruments.
(4) Research and development of quality vortex flowmeters have been carried out at home and abroad. Vortex flowmeters measure mass flow from indirect mass flow meters to direct mass flow meters.
In China, the development of vortex flowmeters is also noticeable. In the early 1970s, Chongqing Institute of Industrial Automation Instrumentation and Beijing Institute of Public Utilities led the research and development of vortex flowmeters. Later, Galaxy Instrument Factory and Kaifeng Instrument Factory also participated in this work. In the mid-1970s, Tianjin Institute of Industrial Automation Instrumentation and the Institute of Automation of the Ministry of Metallurgy also successively invested in the research and development of vortex flowmeters.
By 1950, domestically developed thermal type (including hot wire detection method and thermistor detection method) and ultrasonic vortex flowmeters were successfully developed. Two years later, the stress-type vortex flowmeters were successively launched, followed by the strain-type and vibratory-body vortex flowmeters.
Throughout the 1950s, it was the time when vortex flowmeters developed rapidly in China. Stress vortex flowmeters became a hot spot. According to statistics from a meeting in 1987, there were more than 20 companies engaged in the development and production of vortex flowmeters in China.
After the mid-1950s, another important aspect of the development of vortex flowmeters in China was the introduction of foreign technologies. Some qualified companies have successively introduced the mature products of stress type, thermal type, vibrating body (disc) type and differential switched capacitor vortex flowmeter from Yokogawa, U.S. Eastech, Germany E+H, and Japan OVAL. . At the same time, the state also invested some funds to support enterprises and institutions to develop new products for vortex flowmeters. Chongqing Institute of Industrial Automation Instrumentation undertakes research and development of anti-corrosion vortex flowmeters for special chemical media and quality vortex flowmeters; development of another quality vortex flowmeter for Beijing Institute of Public Utilities; Ministry of Metallurgy The Changsha Institute of Mines is engaged in the development of dual-body-stress vortex flowmeters; the Shanghai Institute of Metrology and Measurement has developed detection components for high-temperature stress vortex flowmeters. These research and development projects have achieved high levels of results. Some domestic enterprises have a special interest in vortex flowmeters, and they have joined the development and production of vortex flowmeters in the form of technology transfer or cooperative development. According to statistics from 1992, there are more than 30 enterprises and institutions that have developed and produced vortex flowmeters in China, and the annual output has reached 8,000 to 9,000 units.
In the mid-1980s, the technical foundation work of vortex flowmeters was also carried out in depth. In 1987, led by the Shanghai Institute of Industrial Automation Instrumentation and the China Institute of Metrology, more than 10 domestic companies participated in the development of industry standards for vortex flow sensors and national metrological verification procedures. The standards and procedures were promulgated in 1989 and played a role in regulating the development, production, and application of vortex flowmeters in China.
The dry calibration technology of vortex flowmeter has been concerned by various parties. Since the early 1980s, some domestic experts and scholars have realized the vortex flowmeter dry calibration after analyzing the characteristics of vortex flowmeters. In the mid-1980s, they combined the process of throttling device standardization, put forward the idea of ​​dry calibration of vortex flowmeters, and put forward suggestions at the national traffic industry development planning meeting. The state has adopted the recommendations of experts and listed the work in the national “September 5th†scientific and technological research plan. The Chongqing Institute of Industrial Automation Instrumentation led the project and assumed the scalar flowmeter dry calibration experimental study. In the past few years, a large number of experimental studies have been conducted to achieve phased results.
After the mid-1990s, the development of vortex flowmeters in China developed towards integration, multi-parameter detection, and intelligence, and achieved remarkable results. Many companies introduced intelligent products.
The development of anything can never be easy, and the development of vortex flowmeters is the same. After a period of sunny days in the mid- and late 1980s, the development of vortex flowmeters slowed down since the early 1990s. Due to the lack of experience in the production, design, selection, and application of this new type of instrument, in the face of various scenes and measurement objects of all walks of life, some problems are gradually exposed. For example, the applicable object and measuring range, the selection of measuring range and measuring pipe diameter, the influence of installation, the resistance to field disturbances (including pipeline vibration and electromagnetic interference) of stress-type vortex flowmeters, the high-temperature resistance of detection elements, and the vortex flow rate The compatibility between the transmitter and the automatic control system, as well as the product manufacturing quality, product calibration, and other issues. These problems have caused vortex flowmeters to fail to achieve satisfactory results in some field applications. Users have opinions, design units have difficulties, and production companies are struggling to respond to emergencies.
These problems have caused some experts to reflect on the design and selection of vortex flowmeters, and issued a prudent call for the design and selection of vortex flowmeters. For a period of time, both design institutes and users have lost their minds, including the imported instruments. The “Vortex Street Heat†began to cool down, and the vortex flowmeter saw a low tide.
The appearance of such a situation in vortex flowmeters is not a bad thing. It is a concrete manifestation of the tortuous nature of things. The appearance of such a situation can cause the relevant personnel in the development, production, design, and application sectors to pay attention. Development and production units should also devote themselves to research and solve the weak links of vortex flowmeter products. Improve product performance and manufacturing quality, product promotion should be more objective; this situation has prompted design agencies and users to be more cautious in product selection and application, and strengthen communication and cooperation with manufacturers; this situation The emergence of this phenomenon has also led to the evolution of the product structure. Some enterprises with weak technical strength, insufficient production equipment and testing conditions, and difficulties in ensuring product quality, cannot provide users with quality services, and are gradually being eliminated by the market.
Throughout the 21st century, vortex flowmeters that have experienced baptism have gradually come out of the trough and embarked on a steady development path. With the national economic development, the application of vortex flowmeters in various fields has gradually expanded. With the improvement of product quality, standardization of design, selection, installation and use, enhancement of pre- and post-sale services, and reduction of on-site failure rate, user satisfaction has improved and confidence has been restored.
In the mid to late 1990s, we also saw many reports and papers on the success of vortex flowmeters in enterprise applications. These articles compare the technical characteristics and technical parameters of orifice flowmeters and vortex flowmeters from different aspects. It is considered that vortex flowmeters are a kind of flow meters that are worthy of promotion and have broad development prospects.
Since the late 1990s, smart vortex flowmeters have entered the market. It overcomes the shortcomings of conventional vortex flowmeters, and the inherent advantages of vortex flowmeters continue to play, making vortex flowmeters a new level of performance, functionality, and quality. According to the information provided by relevant experts, by the beginning of 2004, a new situation has emerged in the development and production of vortex flowmeters in China. The number of production enterprises has exceeded 200, and the annual output has exceeded. 30,000 units. Some provinces (cities) have more than 20 companies that produce and manage vortex flowmeter products.
It is believed that under the joint efforts of all aspects of development, manufacture and application, the young vortex flowmeter will develop and grow under the care, care and support of all parties, and it will become an important member of the flow meter family.
In nature, there are many fluid vibration phenomena. For example, a flag flies in the wind; a wild overhead wire emits a buzzing sound in the wind; a small stream makes water grasses, seedlings, and small trunks swing frequently, and is a concrete manifestation of fluid vibration. In the phenomenon of hydrodynamic oscillation, there is a correspondence between the frequency of fluid vibration and the flow velocity. Flowmeters that use this principle to measure flow include vortex shedding flowmeters (VortexSheddingFlowmeter), commonly known as vortex flowmeters, vortex precessing flowmeters (often known as precessional vortex flowmeters, and fluidic flowmeters).