DE1048425B

DE1048425B -

Info

Publication number: DE1048425B
Application number: DENDAT1048425D
Authority: DE
Publication date: 1959-01-08

Description

DEUTSCHESGERMAN

Die Erfindung bezieht sich auf einen Strömungsmesser, und ihr liegt die Aufgabe zugrunde, diesen so auszugestalten, daß er eine sehr niedrige Zeitkonstante hat, einen sehr geringen Druckabfall verursacht und auf die Massenströmungsgeschwindigkeit, d. h. auf die in GewichtseinTieTten" je Zeiteinheit gemessene Strömung und nicht nur äuFdas Volumen je Zeiteinheit, anspricht.The invention relates to a flow meter, and it is based on the object of designing it so that it has a very low time constant, causes a very low pressure drop and does not affect the mass flow velocity, ie the flow measured in weight units per unit of time only the volume per unit of time responds.

Sehr häufig ist es nämlich erforderlich, die Massenströmungsgeschwindigkeit von Fluden zu bestimmen. Diese Aufgabe hat bisher erhebliche Schwierigkeiten bereitet, da die Entwicklung der hierfür geeigneten Strömungsmesser nicht Schritt mit der Entwicklung mancher Zweige der Technik gehalten hat, bei denen derartige Massenströmungsmesser verwendet werden. Man hat sich daher damit beholfen, die Massenströmungsgeschwindigkeit durch Verwendung verschiedener Meßinstrumente zu bestimmen, welche die Geschwindigkeit, den Druck und die Temperatur des strömenden Fluds ermitteln. Aus diesen Größen kann man dann mit Hilfe von Tabellen oder durch Berechnungen die Massenströmungsgeschwindigkeit ableiten. Denn diese ist eine Funktion der Geschwindigkeit, des Querschnitts und der Dichte des Fluds. Da sich die Dichte mit dem Druck, der Höhe und der Temperatur ändert, ist die Berechnung genauer Beträge der Massenströmungsgeschwindigkeit mühselig und zeitraubend.It is very often necessary to determine the mass flow velocity of fluids. This task has presented considerable difficulties so far, since the development of the appropriate Flowmeter has not kept pace with the development of some branches of technology in which such mass flow meters can be used. One has therefore made use of the mass flow velocity by using various measuring instruments to determine what the speed, pressure and temperature of the determine the flowing flud. You can then use tables or calculations from these values derive the mass flow rate. Because this is a function of the speed, of the Cross-section and the density of the flud. Since the density changes with the pressure, the altitude and the temperature changes, the calculation of precise amounts of the mass flow rate is cumbersome and time consuming.

Der Strömungsmesser nach der Erfindung ist nun gekennzeichnet durch ein den zu messenden Strom leitendes, einen gekrümmten Kanal bildendes Fühlelement, das mit seinem einen Ende im Inneren einer Kammer gelagert und mit dem anderen Ende ohne Abstützung angeordnet ist und sich in Berührung mit Einrichtungen zum Messen des Rückstoßes befindet, den der den gekrümmten Kanal durchfließende Strom erzeugt.The flow meter according to the invention is now characterized by the current to be measured conductive, a curved channel forming sensing element, which with its one end in the interior of a Chamber mounted and arranged with the other end without support and is in contact with Means are located for measuring the recoil caused by the current flowing through the curved channel generated.

Unter anderen Gesichtspunkten betrachtet ist der Strömungsmesser nach der Erfindung gekennzeichnet durch einen von dem zu messenden Strom durchströmten biegsamen Krümmer, der mit Einrichtungen zum Messen des Rückstoßes versehen ist, den der Strom infolge seiner Richtungsänderung im Krümmer auf diesen ausübt.Viewed from other points of view, the flow meter according to the invention is characterized through a flexible elbow through which the current to be measured flows, which is equipped with devices is provided for measuring the recoil caused by the flow as a result of its change of direction in the manifold exercises on this.

Vorzugsweise messen die Einrichtungen zur Bestimmung des Rückstoßes die durch diesen erzeugten größten Spannungen in dem Fühlelement bzw. dem Krümmer und liegen an dessen am stärksten beanspruchten Zonen an.Preferably, the means for determining the recoil measure the recoil generated by it greatest stresses in the sensing element or the manifold and are on the most heavily stressed Zones.

Durch die Erfindung werden die Nachteile der früher verwendeten Verfahren zur Bestimmung der Massenströmungsgeschwindigkeit vermieden. Insbesondere eignet sich der Strömungsmesser zum Bestiinmeii der Strömungsmenge flüssiger Brennstoffe für Strahlantriebe.The invention eliminates the disadvantages of the previously used methods for determining the Avoided mass flow rate. In particular, the flow meter is suitable for Determination of the flow rate of liquid fuels for jet propulsion.

StrömungsmesserFlow meter

Anmelder:Applicant:

General Electric Company, Schenectady, Ν. Υ. (V. St. A.)General Electric Company, Schenectady, Ν. Υ. (V. St. A.)

Vertreter: Dipl.-Ing. Μ. Licht, Patentanwalt, Berlin-Steglitz, Borstellstr. 51Representative: Dipl.-Ing. Μ. Light, patent attorney, Berlin-Steglitz, Borstellstr. 51

Beansprudite Priorität: V. St v. Amerika vom 27. Oktober 1955Claimed priority: V. St v. America October 27, 1955

Frederick Kemp Glasbrenner, North Syracuse, Ν. Y., und William Emmanuel Lyons, Rexford, N. Y. (V.St.A.), sind als Erfinder genannt wordenFrederick Kemp glass burner, North Syracuse, Ν. Y., and William Emmanuel Lyons, Rexford, N. Y. (V.St.A.), have been named as inventors

Der Meßbereich des Strömungsmessers nach der Erfindung umfaßt Schwankungen der Strömungsmenge im Verhältnis 10:1. Dabei l^eläuft sich die Zeitkonstante auf höchstens 10 Millisekunden. Die Temperaturen des vermessenen Stromes können zwischen 60 und 250° F (16 und 121° C) schwanken. Auch die Drücke des vermessenen Stromes können sich in weiten Grenzen ändern, nämlich von 0 bis 140 atü. Dabei beläuft sich der Druckabfall bei einer Massenströmungsmenge von 18 000 kg je Stunde auf weniger als 0,7 kg/cm². Die Meßgenauigkeit beläuft sich auf plus oder minus 1 %>.The measuring range of the flow meter according to the invention comprises fluctuations in the flow rate in a ratio of 10: 1. The time constant runs to a maximum of 10 milliseconds. The temperatures of the measured stream can vary between 60 and 250 ° F (16 and 121 ° C). The pressures of the measured current can also change within wide limits, namely from 0 to 140 atmospheres. At a mass flow rate of 18,000 kg per hour, the pressure drop is less than 0.7 kg / cm ² . The measuring accuracy is plus or minus 1%>.

Ein bevorzugtes Ausführungsbeispiel der Erfindung zeichnet sich dadurch aus, daß es keine beweglichen Teile aufweist.A preferred embodiment of the invention is characterized in that there are no movable ones Has parts.

In den Zeichnungen, in denen an Hand eines Beispiels der Gegenstand der Erfindung dargestellt ist, zeigtIn the drawings, in which the subject matter of the invention is illustrated by way of an example is shows

Fig. 1 einen teilweise im Schnitt gehaltenen Aufriß des Strömungsmessers undFig. 1 is an elevation view, partly in section, of the flow meter;

Fig. 2 ein elektrisches Schaltschema mit einer Brückenschaltung, die bei diesem Meßgerät zur Verwendung gelangt.2 shows an electrical circuit diagram with a bridge circuit which is used in this measuring device got.

Der zu vermessende Strom fließt durch ein Einlaß rohr 11, das bei 13 mit einer Kappe 12 verschraubt ist; An dieser liegt eine aus einem Knierohr bestehende Kammer 14 an, die also an ihrem einen Ende durch die Kappe abgeschlossen ist. Zwischen dieser und dem Knierohr befinden sich ein hohler Dichtungsring 15 sowie eine innere Dichtungsmanschette 16. The current to be measured flows through an inlet tube 11 which is screwed at 13 with a cap 12; A chamber 14 consisting of an elbow tube rests against this, which is thus closed off at one end by the cap. A hollow sealing ring 15 and an inner sealing collar 16 are located between this and the elbow tube.

809 728/83809 728/83

Claims

As a result, the joint between the cap 12 and the chamber 14 is sealed. A union nut 17 serves the purpose of screwing the elbow tube 14 onto the cap 12. A straight pipe section 18 is screwed with its upper end from the inside into the cap 12, namely opposite the inlet pipe 11. The lower end of the pipe section 18 facing away from the cap is now somehow firmly connected to a sensing element forming a curved channel. z. B. by a press fit, by a screw connection, or by a welded connection. The pipe section 18 is provided with a section 22 of weakened cross section which can bend under the effect of the jet recoil. The bending stresses are distributed over the section between the screw connection with the cap 12 on the one hand and the curved pipe on the other hand. The tensile and compressive stresses generated by the recoil in the thin walls of the section 22 are determined by electrical resistance measuring elements 23 and 24, which are adhered to both sides of the weakened pipe section 22 and are excited via connecting lines 25 and 26. These lines pass through bushing insulators 27 which are arranged in the cap 12. The free end of the pipe bend 18, 19 is provided with a vibration damper in the form of an annular weight 28 which is somehow held loosely in its position, e.g. B. by snap rings 29, which sit in the circumferential grooves of the pipe wall. The drain line is fastened to the elbow pipe 14 with the aid of an intermediate piece 31. As FIG. 2 shows, the measuring elements 23 and 24 for determining the tensile and compressive stresses with electrical resistors 32 and 33 are located in a bridge circuit. This can be brought into equilibrium by the control resistor 33, which is indicated by a galvanometer 34. In operation, the flow to be measured is first passed from the inlet pipe 11 into the straight pipe section 18 and from there through the curved pipe 19 into the connecting pipe 21, from where the current passes into the drain line shown. Since the liquid flows under pressure, it accumulates in the connecting pipe 31 and flows around the elbow 18, 19 in the elbow pipe 14 Tube 18 tensile and compressive stresses are generated. These seek to put the measuring element 23 under compressive stress and the measuring element 24 under tensile stress. However, this has the effect that the electrical resistance of the measuring element 23 decreases and that of the measuring element 24 increases. As a result, the balance of the bridge circuit is disturbed and this disturbance is indicated by the galvanometer 34. This display represents a measure of the recoil acting on the pipe elbow 18, 19. However, this recoil is influenced by the density of the flow as a function of a square root. In order to derive a control variable from the flow meter which is proportional to the mass flow, the output measured variable is multiplied by a variable which is proportional to the density of the flow, and the square root is formed from the product. In practice, one proceeds in such a way that one calibrates the division of the galvanometer 34 in such a way that it indicates the flow rate at a density of 1.0. The value read is then multiplied by the actual density of the fluid and the square root is formed from the product ίο. In this way the actual mass flow rate per unit of time is determined. The sensing element, which consists of the straight pipe section 18 in the curved pipe 19, naturally has a natural frequency which, in the absence of special precautions, could resonate with the pulse of the current, which is usually generated by a pulsating pump. The resonance would then occur at a certain speed of the ao pump and possibly lead to fatigue of the sensing element and to a change in its parameters. This is now largely avoided by the annular weight 28, which sits on the free end of the manifold and is loosely fitted there. Due to its friction on the manifold, the weight dampens any vibrations, which is also due to the viscosity of the fluid. The effect of the resonance is weakened so much that it does not lead to any disturbances. The illustrated embodiment can be modified in many ways. Thus, the sensing element does not necessarily have to consist of a flexible bend, but it can also form, for example, a U-shaped curved channel. Pathntans pb oc.HE:

1. Flow meter, characterized by a sensing element (18, 19) which conducts the current to be measured and forms a curved channel, one end of which is mounted inside a chamber (14) and the other end is arranged without support and is in contact with means (23, 24) for measuring the recoil.

2. Flow meter according to claim 1, characterized in that the devices (23, 24) for measuring the recoil measure the greatest stresses generated by this in the sensing element or the manifold (18, 19) and bear against the most heavily stressed zones.

3. Flow meter according to claim 2, characterized in that the sensing element or the manifold (18, 19) is provided with a vibration damper (28) .

4. Flow meter according to claim 3, characterized in that the vibration damper consists of an annular weight (28) which is loosely mounted on the sensing element or the manifold (18, 19) at its outlet end.

5. Flow meter according to claim 1, characterized in that the elbow (18, 19) has a weakened cross section upstream to which the measuring elements (23, 24) are adhesively attached.

1 sheet of drawings