JP2010134383A - Apparatus and method for reproduction of cavitation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily reproduce cavitation in a simple structure in winter or the like. <P>SOLUTION: An apparatus increases the temperature of water W in a water storage tank 2 with a heater 3, sucks the water W in the water storage tank 2 with a pump 4, and lowers a pressure on a suction opening side of the pump 4 with a pressure regulating valve 51 to generate cavitation. Thereby, even in winter or the like whose atmospheric temperature is low, water temperature is high and saturated vapor pressure of water W is high, so that cavitation is generated even when the pressure on the suction opening side of the pump 4 is not significantly lowered. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cavitation reproduction apparatus and a cavitation reproduction method for experimentally reproducing cavitation (cavity phenomenon).

Cavitation is a physical phenomenon in which bubbles are generated and disappeared in a short time due to a pressure difference in a liquid flow. An apparatus that experimentally reproduces and feels such cavitation is known (for example, see Patent Document 1). By reducing the pressure (inlet pressure) on the suction port side of the pump below the saturated vapor pressure, this device can generate cavitation in the transparent pipe on the suction port side and observe the generation of bubbles from the outside. It is a thing.
Utility Model Registration No. 3070329

  By the way, the saturated vapor pressure varies depending on the temperature. When the water temperature is high, the saturated vapor pressure is high, and when the water temperature is low, the saturated vapor pressure is low. For example, when the water temperature is 30 ° C., the saturated vapor pressure is 31.8 mmHg, whereas when the water temperature is 10 ° C., the saturated vapor pressure is 9.20 mmHg. For this reason, when cavitation is reproduced by a conventional apparatus in winter when the water temperature is low, it may be difficult to lower the pressure on the suction port side of the pump below the saturated vapor pressure because the saturated vapor pressure is low. Further, if the pressure on the suction port side of the pump is greatly reduced, the negative pressure increases, and the transparent pipe or the like must be structured to withstand this negative pressure, which increases equipment costs.

  Therefore, an object of the present invention is to provide a cavitation reproduction device and a cavitation reproduction method that can reproduce cavitation easily and with a simple structure even in winter.

  In order to achieve the above object, the invention described in claim 1 includes a tank for storing liquid, a pump for sucking out liquid in the tank, pressure adjusting means for adjusting pressure on the suction port side of the pump, and the tank. And a temperature adjusting means for adjusting the temperature of the liquid inside the cavitation reproduction device.

  According to this invention, the temperature of the liquid in the tank is adjusted to a predetermined / desired temperature by the temperature adjusting means, the liquid in the tank is sucked out by the pump, and the pressure on the suction port side of the pump is adjusted by the pressure adjusting means. As a result, cavitation occurs.

  The invention according to claim 2 is characterized in that the temperature of the liquid in the tank is adjusted, the liquid in the tank is sucked out by a pump, and the pressure on the suction port side of the pump is adjusted to generate cavitation. This is a cavitation reproduction method.

  According to the first and second aspects of the present invention, the saturated vapor pressure rises by adjusting the temperature of the liquid in the tank in the winter season when the air temperature is low, so the pressure on the suction port side of the pump is increased. Cavitation can be generated without lowering. In addition, since only the temperature of the liquid in the tank needs to be adjusted by heating, the structure is simple and the equipment cost can be reduced. Further, cavitation due to temperature change of the liquid in the tank can be reproduced. That is, conventionally, cavitation has been reproduced only by reducing the pressure on the suction port side of the pump below the saturated vapor pressure. On the other hand, according to the present invention, since the saturated vapor pressure varies depending on the temperature of the liquid, it is possible to reproduce the cavitation that occurs with the temperature change of the liquid.

  The present invention will be described below based on the illustrated embodiments.

  FIG. 1 is a schematic configuration diagram showing a cavitation reproduction apparatus 1 according to an embodiment of the present invention. The cavitation reproduction apparatus 1 is an apparatus that experimentally reproduces cavitation (pump cavitation), and includes a water storage tank (tank) 2, a heater (temperature adjusting means) 3, a pump 4, and the like.

  The water storage tank 2 is a tank for storing water (liquid) W, and a heater 3 and a water temperature gauge 31 are disposed in the water storage tank 2. The heater 3 is a heater that heats the water W in the water storage tank 2, and the water thermometer 31 is a thermometer that constantly measures the temperature of the water W. The heater 3 and the water thermometer 31 are connected to a control panel 32. Yes. The control panel 32 includes an input unit for setting and inputting the temperature, and based on the measurement result from the water thermometer 31 so that the temperature of the water W in the water storage tank 2 becomes the temperature set by this input unit. The heater 3 is activated. That is, when the water temperature is lower than the set temperature, the heater 3 is operated to heat the water W, and the water temperature is adjusted to the set temperature. On the other hand, when the water temperature is equal to or higher than the set temperature, the heater 3 is not operated.

  As described above, in this embodiment, the water temperature is adjusted to be equal to or higher than a predetermined / desired temperature by heating the water W. This is mainly intended to facilitate the reproduction of cavitation, as will be described later. Because it does. On the other hand, when it is desired to always reproduce cavitation at a constant water temperature (for example, 25 ° C.), a cooler or the like is provided in addition to the heater 3 to heat and cool the water W. May be.

  The water storage tank 2 is connected to the suction port side of the pump 4 via the first pipe 21. The pump 4 is a pump that sucks out the water W in the water storage tank 2 by using the motor M as power. A pressure adjusting valve (pressure adjusting means) 51 is disposed in the first pipe 21, and further, on the suction port side of the pump 4. The observation pipe 41 is disposed in the front. The pressure adjustment valve 51 is a valve that adjusts the pressure on the suction port side of the pump 4, and reduces the pressure on the suction port side of the pump 4 by narrowing the pressure adjustment valve 51 as will be described later. The observation pipe 41 is made of transparent or translucent acrylic, and as shown in FIG. 2, the suction port side (inlet side) of the pump 4 is also casing with a transparent or translucent acrylic cover 4a. The observation pipe 41 and the acrylic cover 4a are connected.

  A second pipe 22 is connected to the discharge port side of the pump 4, and the other end of the second pipe 22 is connected to the water storage tank 2. Thereby, the water W discharged from the pump 4 is returned to the water storage tank 2 via the second pipe 22. In addition, an outlet valve 52 is disposed in the second pipe 22, and a first pressure gauge 61 and a second pressure gauge 62 are disposed on the suction port side and the discharge port side of the pump 4, respectively. .

  Next, the operation of the cavitation reproduction apparatus 1 having such a configuration and the cavitation reproduction method by the cavitation reproduction apparatus 1 will be described.

  First, the temperature of the water W in the water storage tank 2 is adjusted to a predetermined temperature. That is, as described above, the set temperature is input at the input unit of the control panel 32. Here, the temperature is set to a temperature at which cavitation can be generated smoothly and easily, that is, the saturated vapor pressure of the water W becomes high regardless of changes in temperature due to the season. In this embodiment, it is set to 30 ° C., for example. Thus, even when the temperature is low and the water temperature in the water storage tank 2 is low, the water W is heated by the heater 3 as described above, and the water temperature is maintained at 30 ° C.

  In this state, the pressure regulating valve 51 is “open” and the outlet valve 52 is “closed”. Next, the pump 4 is started, the water W in the water storage tank 2 is sucked out, the outlet valve 52 is gradually opened, and the pressure on the outlet side of the pump 4 (measurement result by the second pressure gauge 62) is set to a predetermined pressure. Adjust to. In this state, looking at the observation pipe 41 and the acrylic cover 4a, it is confirmed that no bubbles are generated on the suction port side of the pump 4 and that the pump 4 is operating normally.

  Next, the pressure regulating valve 51 is gradually throttled to reduce the pressure on the suction port side of the pump 4 to generate cavitation. At this time, the pressure regulating valve 51 is throttled so that the pressure on the suction port side of the pump 4 (measurement result by the first pressure gauge 61) does not become a predetermined pressure or less. Then, the occurrence status of cavitation is confirmed. That is, whether vibration or abnormal sound is generated in the pump 4 or the first pipe 21, hunting (a phenomenon in which the needle shakes violently) occurs in the pressure gauges 61 and 62, the observation pipe 41 or the acrylic cover 4 a is attached. Check whether bubbles are generated on the suction port side of the pump 4. After confirming the occurrence of cavitation in this way, the pressure regulating valve 51 is fully opened, the outlet valve 52 is fully closed, and the pump 4 is stopped. Here, these operations may be performed manually or may be automatically controlled by a program.

  As described above, according to the cavitation reproduction device 1 and the cavitation reproduction method, the temperature of the water W in the water storage tank 2 is always 30 ° C. and the saturated vapor pressure is maintained high even in winter when the temperature is low. Yes. For this reason, cavitation can be easily generated without greatly reducing the pressure on the suction port side of the pump 4. As a result, it is not necessary to make the observation pipe 41, the acrylic cover 4a, or the like a structure that can withstand a large negative pressure. In addition, since it is only necessary to heat the water W in the water storage tank 2, the structure is simple and the equipment cost can be reduced.

  By the way, conventionally, cavitation was reproduced only by lowering the pressure on the suction port side of the pump below the saturated vapor pressure, but according to this embodiment, due to the temperature change of the water W in the water storage tank 2 Cavitation can be reproduced. For example, by generating a constant pressure on the suction port side of the pump 4 and gradually increasing the temperature of the water W in the water storage tank 2, the occurrence of cavitation due to an increase in the saturated vapor pressure as the water temperature increases is reproduced. can do. Thus, according to this embodiment, it is possible to reproduce and experience the occurrence of cavitation due to both pressure and temperature factors.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in the above embodiment, the cavitation reproduction apparatus 1 is a single phenomenon reproduction apparatus. However, in the apparatus that reproduces a plurality of phenomena, the mechanism of the cavitation reproduction apparatus 1 is applied to a mechanism that reproduces cavitation. May be. In other words, when water tanks, pumps, control devices, etc. are shared to reproduce multiple phenomena such as cavitation, water hammer, gate valve backflow, etc., the water in the water tank is heated and saturated when reproducing cavitation. The vapor pressure may be increased.

It is a schematic block diagram which shows the cavitation reproduction apparatus which concerns on embodiment of this invention. It is a figure which shows the connection state of the pump and observation pipe of the cavitation reproduction apparatus of FIG.

Explanation of symbols

1 Cavitation reproduction device 2 Water storage tank (tank)
21 1st piping 22 2nd piping 3 Heater (temperature adjustment means)
31 Water temperature gauge 32 Control panel 4 Pump 4a Acrylic cover 41 Observation pipe 51 Pressure adjustment valve (pressure adjustment means)
52 Outlet valve 61 First pressure gauge 62 Second pressure gauge W Water (liquid)

Claims (2)

  A tank for storing liquid, a pump for sucking out the liquid in the tank, pressure adjusting means for adjusting the pressure on the suction port side of the pump, and temperature adjusting means for adjusting the temperature of the liquid in the tank. A cavitation reproduction device characterized by A cavitation reproduction method characterized by adjusting the temperature of the liquid in the tank, sucking out the liquid in the tank by a pump, and adjusting the pressure on the suction port side of the pump to generate cavitation.

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