GB2240817A

GB2240817A - Reaction-jet turbine

Info

Publication number: GB2240817A
Application number: GB9002996A
Authority: GB
Inventors: Vladimir Petrovich Ena; Sergei Konstantinovich Korolev; Viktor Ivanovich Litvinenko; Irina Alexandrovna Marochkina; Pavel Pavolich Prikhodchenko; Vladimir Viktorovich Psarev; Jury Leonidovich Rukhlov; Vadim Vasilievich Sayapin; Nikolai Dmitrievich Fedorenko
Original assignee: VNI I KT I KOMPRESSORNOGO MASH
Current assignee: VNI I KT I KOMPRESSORNOGO MASH
Priority date: 1990-02-09
Filing date: 1990-02-09
Publication date: 1991-08-14
Also published as: GB9002996D0; FR2658862A1; DE4004733A1

Abstract

A reaction-jet turbine has a rotor 1 in the form of a shaft 2 having at least one axial passage 3, and at least one gas dynamic supply device in the form of a supply pipe 17 positioned coaxially with the shaft in a spaced relation delta to the end thereof. At least one jet pipe 10 is cantilevered to the shaft 2 and has at the distal end thereof a thrust nozzle 12 communicating with an end inlet 5 of the axial passage 3 so as to form a continuous gas duct. The outlet portion of the supply pipe 17 is made in the form of a supply nozzle 19 having the minimum cross-sectional area thereof which is smaller than the minimum cross-sectional area of the thrust nozzle 12, the ratio between these areas being chosen to ensure a shock wave in the entry zone of the axial passage 3 of the shaft 2. <IMAGE>

Description

:2:2.4 C a 1 _ 7 REACTICN-JET TURBINE The invention relates to turbine

manufacture.

and, more specifically, it is concerned with reaction -jet turbines.

The invention may be most advantageously used in power actuators of various systems, in particular, in re versible actuators of shut-off and control fittings.

The-invention provides a reaction-jet turbine comprising a rotor in the form of a shaft having at least one axial passage, at least one jet pipe cantilevered to the shaft having at the distal end thereof a thrust nozzle communicating with an end inlet of the axial pass age so as to form a continuous gas duct, and at least one gas dynamic supply device in the form of a supply pipe positioned coaxially with the shaft in a spaced re lation to the end thereof, the outlet portion of the pipe being in the form of a supply nnzzle whose mi nimum cross-sectional area is smaller than the minimum cross-sectional area of the thrust nozzle, the ratio of these areas ensuring a shock wave in the entry zone of the axial passage of the shaft.

The provision of the outlet portion of the supply pipe in the form of a supply nozzle enables one to ensure acceleration of fluid and its supply to the axial passage of the shaft at a supersonic velocity with supercritical pressure ratios therein so as to substantially completely eli- minate fluid leakage from the axial passage of the shaft through the clearance space,as weak perturbations (gas flow out of the axial passage under the action of a pressure differential) cannot propagate in opposition to the supersonic flow (pressure wave propagates at the sonic velocity), and only a very insignificant leakage can occur along a thin boundary layer where velocity is lower'than the sonic velocity. The fact that the minimum cross-sectional area of the supply nozzle is smaller than the minimum cross-sectional area of the thrust nozzle is the necessary condition to ensure supersonic supply of fluid to the axial passage of the shaft which follows from the theoretical relationship:

S 1 S 3 1 =>S < S U7 or -g- 3 3 whe re in S 1 whe rein P^ po 3 is the minimum cross-sectional area of the supply nozzle; S is the minimum cross-sectional area of the thrust nozzle; (Y is the coefficient of recovery of full pressure in the portion between the entry to the supply nozzle and the inlet of the thrust nozzle (characteristic of energy losses).

Po 3 is the full pressure upstream the thrust nozzle; is the full pressure upstream the supply nozzle.

The provision of the supply and thrust nozzles with the minimum crosssectional areas in a ratio ensuring a shock wave (transition from a supersonic to subsonic velocity of the fluid flow) in the entry zone of the axial passage of the shaft minimizes energy losses (full pressure recovery coefficient C'tends to its maximum) since otherwise, if a shock wave is remote f rom the inlet, fluid flow through the axial passage at a supersonic velocity upstream a shock wave is accompanied by higher energy losses. On the other hand, if a shnck wave is outside the axial passage, in the clearance space and at a certain distance from the end inlet, a subszantial fluid leakage occurs from the axial passage of the shaft into the clearance space between the shock wave and the end inlet. It is most preferred that the abovementioned nozzles be constructed with a ratio which is slightly S 3 different from the theoretical ratio - ,n- which cnrresponds to the value of S 3 which obtains when the shock wave is directly in the section of the and inlet, i.e. S 3 with U- = k o,3, wherein k is the empiric coefficient. A decrease in specific thrust caused in this case by a slight leakage of fluid to a certain extent is compensated for to a larger degree owing to an increase in specifie thrust owing to a decrease in losses in the shock wave of a lower intensity since the supersonic jet does not expand in the clearance space to the size of the cross-sectional area of the end inlet of the axial passage of the shaft, and velocity of the jet upstream the shock wave in the clearance space is lower than velocity upstream the shock wave which is in the section of the end inlet of the axial passage of the shaft.

The provision of the outlet portion of the supply 5 pipe in the form of a subply nozzle ensures, in compari- son with the prior art. the possiblity of an increase.in the space between the supply nozzle and the end inlet of the axial passage of the shaft so as to lower requirements imposed upon construction of the reaction-jet turbine, according to the invention, and enhance its reliability by completely ruling out any contact between the end face of the supply nozzle and the end of the shaft and their freezing to each other as moisture drops can escape freely through the clearance space upon stop- page of the reaction-jet turbine.

The supply nozzle is preferably made in the form of a supersonic nozzle.

It the supply nozzle is in the form of a supersonic nozzle. e.g. in the form of the Laval ncizzle, accelerat- ion of fluid flow to a supersonic velocity is ensured upstream the end inlet of the axial passage of the shaft. At the same time, if a narrowing sonic nozzle is used. a premature appearance of a shock wave in the clearance space can occur under certain conditions (low supercritical pressure ratios in the supply nozzle) which causes a substantial fluid leakage.

To ensure guaranteed entry of the jet over its entire cross-section into the axial passage of the shaft.

Z hence to eliminate leakage directly from the jet, it is preferred that the amount of space between an end face of the supply nozzle and the end of the shaft be chosen on the basis of the formula:

J < D 1 - D2 9 2tg X12 wherein 6 is the of the amount of space between the end face supply nozzle and the end of the shaft; D 1 is the diameter of the axial passage of the shaft; D 2 is the diameter of the end face of the supply nozzle; is the angle of taper of the outlet portion of the supply nozzle.

A reaction-jet turbine, according to the inventinn.

may be effectively and widely used in various fields of technology. It has potentially high output parameters, in comparison with turbines of other types which is due to the direct transformation of fluid energy into kinetic energy of a reaction-jet and then into mechanical work in a single stage with a thermodynamic process close to the isoentropic process. It should be noted that with an increase in the available fluid pressure, efficiency of the turbine, according to the invention, increases, and the initial temperature of fluid may vary from low subzero temperatures as low as -60 'C and even lower up to high temperatures over 1000 - 1500 OC. Simplicity of structure of the turbine is due to its single-stage design for any fluid.pressures and simplicity of the flow duct which should not be shaped thus also resulting in low moments of inertia of the rotor. i.e. high dynamic performance of the turbine, its low weight and small size as a whole and high reliability in operation even with contaminated, humid and low-temperature fluid which is also due to the use of an original non-contact gas dynamic supply device. These advantages bring about the effective use of reaction-jet turbines, according to the invention, as power members of actuators of various systems and units with a power ranging from several watts to megawatts, e.g. ir- control systems, including servo systems; in actuators of gas control fittings working with contaminated, humid and low-temperature gases; in drives of turbopump and turbocompressor plants; in air- craft gas turbine-engines, and the like. The invention will now be described with reference to a specific embodiment illustrated in the accompanying drawings. in which: 20 Fig. 1 is a longitudinal section of a reaction-jet turbine according to the invention; Fig. 2 is an axial view of a reaction-jet turbine shown in Fig, 1; Fig. 3 is a sectional view taken along line III-III ir- Fig. 2; Fig. 4 is a sectional view taken along line IV-IV in Fig. 2-; Fig. 5 is an enlarged longitudinal sectional view of an embodiment of a thrust nozzle; I Fig. 6 is an enlarged view taken along arrow VI in Fig. 1 diagrammatically showing fluid flow; Fig. 7 is relationship of specific thrust versus minimum (critical) cross- sectional area of the thrust nozzle with a constant minimum cross- sectional area of the supply nozzle; and Fig. 8 is a sectional view of an embodiment of an actuator for a combination drive of a gas control fitting using a reaction-jet turbine according to the invention.

A reaction-jet turbine according to the invention comprises a rotor 1 (Fig. 1) in the form of a shaft 2 having two axial passages 3 and 4 insulated from each other. End inlets 5 and 6 of respective axial passages 3 and 4 are provided on either end of the shaft 2. The shaft 2 is journalled in bearings 7 (e.g. in antifrict- -ion or sliding-contact bearings) and has a drive gear 8 for transmitting torque to an actuator (not shown).

A bushing 9 put on the shaft 2 supports two cantile- vered radially extending jet pipes 10 and 11 having at their distal ends thrust nozzles 12 and 13, respectively. The thrust nozzles 12 and 13 are oriented in one and the same direction transversely with respect to the longitudinal axis of the shaft 2 for developing torque on the shaft 2 under the action of thrust force.

The thrust nozzles 12 and 13 communic-ate through interior spaces of the jet pipes 10 and 11, respectively,, with the respective axial passages 3 and 4 and with their.

end inlets 5 and 6 so as to form continuous gas ducts.

To lower hydraulic losses, the jet pipes 10 and 11 (Fig. 2) are made curvilinear, and to lower aerodynamic drag during rotation of the rotor 1 (Fig. 1) and to make -5 them more rigid. each jet pipe 10 and 11 is covered by a fairing 16 (Fig. 2). In addition, to lower aerodynamic drag, the jet pipes 10 and 11 may be made without fairings, but in such case they should have a streamlined configuration in the cross-section, e.g. an elliptical configuration as shown in Fig. 3. In case the cross-section of the jet- pipes is made in the form of a ring, the fairing 16 is of a curvilinear cross-sectional configuration to accomplish this so as to define with the jet pipe 10 (11) a streamlined cross-section, e.g. in the form of an ellipse as shown in Fig. 4.

For a rapid replacement of the thrust nozzles 12 and 13 (Fig. 5) upon their rapid wear or in case it is necessary to carry out readjustment of the reaction-jet turbine for different parameters, the thrust nozzles 12 and 13 may be in the form of readily removable bushings_ mounted in a special socket bored in the distal end of the jet pipes 10, 11, respectively.

A pair of gas dynamic supply devices in the form of supply pipes 17 and 18. respectively, are provided up- stream the end inlets 5 and 6 (Fig. 1) coaxially with the axial passages 3 and 4. The,outlet portions of the supply pipes 17 and 18 are in the form of supply nozzles 19 and 20, respectively. The supply nozzles 19 and 20 in this embodiment are in the form of supersonic Laval nozzles. Spaces are defined between end faces 21 and 22 (Fig. 6) of the supply nozzles 19 and 20, respective_ ly, and the end inlets 5 and 6. The amount of the space is chosen based on the formula:

C < D 1 - D 2 2tan y / 2 wherein D1 is the diameter of the axial passage 3(4) of the shaft 2; D2 is the diameter of the end face 21 (22) of the supply nozzle 19 (20); is the angle of taper f of the outlet portion of the supply nozzle 19 (20).

A reaction-jet turbine functions in the following manner.

For rotation of the rotor 1 (Fig. 1) clockwise (as viewed on the side of the distal end of the rotor 1 or on the lefthand side in the drawing), fluid (compressed gas, air or gas produced by a gas generator) is supplied under pressure to the supply pipe 17 of the gas dynamic supply device wherein it is accelerated in the sonic or supersonic supply nozzle 19 to a sonic or supersonic velocity, respectively (this can be done with a supercritical pressure differential at the supply nozzle). A steady supersonic jet is formed downstream the end face 21 of the supply nozzle 19 (Fig. 6) in the axial space J with rigid (unpermeable) boundaries of its contour. The supersonic jet moves through thd axial space J and enters through the end inlet 5 the axial passage 3 of the shaft 2. If the jet enters over the entire cross-sec- tion of the axial passage 3 (i.e. if the boundary of the jet is in touch with the inner surface of the axial passage 3 or contour of the cross- section of the end inlet 5) a gas dynamic sealing of the axial passage 3 with the supersonic flow occurs. This sealing is based on the fact that weak perturbations (shock wave) propagate at the sonic velocity and cannot pass in opposition to the supersonic flow. Accordingly, owing to the presence of a pressure differential, leakages of fluid from the axial passage 3 back into the space J are substantially ruled out. To ensure a supersonic velocity at the entry of fluid to the axial passage 3 over the er-tire cross-seetion thereof and to allow for a maximum possible increase in the amount of space J, configuration of the supersonic jet should correspond to escape conditions from the supply nozzle with an underexpansion (in Fig. 6 the boundary of the jet is shown in the form of two curves), i.e. pressure at the end face 21 of the supply nozzle 19 should be greater than pressure of the environ- ment, or to escape conditions close to the design escape conditions (in Fig. 6 the boundary of the jet is shown in the form of dotted straight lines). i.e. pressure at the end fac e 21 of the supply nozzle 19 should be equal or about equal to the environment pressure. The necessa- ry conditions for the escape of the jet from the supply nozzle 19 are ensured by a spec,ific value of the degree of divergence of the supersonic portion of the supply nozzle 19 (the ratio of the area of the end face 21 of 1 1 the supply nozzle 19 to the minimum cross-sectional area) for given parameters of fluid upstream the supply nozzie 19. The condition of entry of the jet to the end inlet 5 over the entire cross-section thereof (rather than partially, hence, elimination of leakage from the peri pheral part of the jet) is determined by an ultimate ad missible increase in the amount of space i.e. the amount of space J should comply with the inequality:

D1 - D 2 T 2tan X12 max which follows from geometrical considerations for a supersonic jet. After the entrance of the supersonic je through the end inlet 5 a shock wave appears in the axi al passage 3 of the shaft 2 either directly in the zone of the end inlet 5 (Fig. 6) of the axial passage 3 with or at a certain distance from the end inlet 5 3 in the axial passage 3 with < J3 depending on the ratio of the ninimum (critical) cross-sectional areas of the supply nozzle 19 and thrust nozzle 12 (Fig. 5) which complies with the necessary condition of the entrance of a supersonic jet into the axial passage 3 (Fig. 6):

19. L3. L3 < 6 3 S D wherein S 3 is the minimum (critical) cross-sectional area of the supply nozzle 19; S is the minimum (critical) cross-sectional area of the thrust nozzle 12 (Fig. 5); D 3 is the diameter of the minimum (critical) cross-section of the supply nozzle 19 (Fig. 6); D -is the diameter of the minimum (critical) cross-section of the thrust nozzle 12 (Fig. 5); is the coefficient of recovery of full pressure. Transition from subsonic to supersonic velocity of fluid flow occurs in a ahock wave. In Fig. 6 shock waves are shown in the form of vertical undulating lines at which flow conditions are charaCterized by a velocity coefficient A. The velocity coefficient A is the ratio of velocity of flow at a given point to the sonic velocity in the critical section.

Efficiency of operation of a reaction-jet turbine is characterized by the value of specific thrust P (Fig."0 versus area S of the minimum crosssection of the thrust nozzle 12 (Fig. 5) with a constant area and minimum cross-section of the supply nozzle 19 (Fig. 6). In the diagram shown in Fig. 7, (.-) 1 corresponds to the condition U = U 3 and to a position of a shook wave di rectly in the section of the end inlet 5 > 1; 12 < 1). In the diagram (Fig. 7), (..) 2 corresponds to a choking (decrease) of the area of the thrust nozzle 12 (Fig. 5) and illustrates the relationship S k G39 wherein k is the empir:bal coeff ioient (k = 1 2). This (&) 2 corresponds to the maximum value of specific It thrust P =.. at which a shock wave (Fig. 6) is at a short distance from the end inlet 5 upstream in the di rection of flow, i.e. directly within the space > 1; A < 1, and A < A 21 22 21 11). With this posi- tion of a shock wave, a certain leakage of fluid occurs into the space between a shock wave and the end inlet 5, but specific thrust 15 reaches its maximum value. i.e. "' - Pmax owing to a decrease in the shock wave intensity (A21 < A 11). Further "choking" of the thrust nozzle 12 (Fig, 5) results in a greater spacing of the shock wave and in a strongly increasing fluid leakage with a respective decrease in specific thrust (zone A in Fig. 7).

"Opening" (increase) of the area of the thrust nozzle 12 (Fig. 5) to values substantially greater than those at the theory point 1 (Fig. 7) as shown by (.) 3 results in a shock wave shifting in the direction of flow to a position inside the axial passage 3 (Fig. 6) ( A 31 > 1 ' A 32 < 1, with A 31 < A 11). As a result, a decrease in specific thrust l occurs 'zone B) owing to energy losses during movement of a supersonic flow through the axial passage 3 (Fig. 6) upstream a shock wave in spite of the fact that intensity of the shock wave decreases ( A 31 < A 11). Theref ore, the ratio of areas of the minimum cross-sections of the supply nozzle 19 and thrust nozzle 12 (Fig. 5) corresponding to values in the area of 2 (Fig. 7) is close to an optimum one and dictates a shock wave position in the zone of entrance to the axial passage 3 (Fig. 6).

1 g The flow of fluid moves downstream a shock wave through the axial passage 3. through the interior 14 (Fig. 1) of the jet pipe 10 to the thrust nozzle 12. Fluid flow is again accelerated in the thrust nozzle 12 and is ejected into the environment, i.e. potential energy of fluid is transformed into kinetic energy of the jet with the development of reaction thrust at the thrust nozzle 12.

The force of thrust P at the thrust nozzle 12 deve- lops torque on the shaft directed clockwise owing to the arm of the jet pipe 10. The torque is transmitted by means of the drive gear 8 to an actuator. The rotor rotates in the bearings, and mechanical work is performed.

For transmitting torque to an actuator in the opposite direction (counterclockwise), i.e. for reverse, fluid is supplied to the opposite supply device, namely to the supply pipe 18, the fluid supply to the supply pipe 17 being interrupted. Fluid flow moves similarly to the abovedescribed cycle, and fluid enters, after the supply nozzle 20, the end-inlet 6-of the axial passage 4 of the shaft 2 and then moves through the interior 15 of the jet pipe 11 to the thrust nozzle 13 wherein it is accelerated and ejected outside to develop reaction thrust. Reaction thrust at the nozzle 13 develops torque by means of the arm of the jet pipe 11 at the shaft 2 which is directed counterclockwise. The torque is transmitted by means of the drive gear 8 to an actuator.

In reaction-jet turbines where an accurate control 1 is required (e.g. in servo control systems) fluid may be supplied simultaneously to both supply pipes 17 and 18 under different pressures upstream the supply pipes in accordance with an error of the controlled value and 5 with its preset value.

The reaction-jet turbineg according to the invention, can be widely used in gas engines of combination gas control fitting drives, e.g. in actuators of a range of ball valves with a nominal inside diameters from 300 to 1400 mm for a nominal pressure of 8 MPa. Fig. 8 shows such an engine having a easing 23 accommodating a reaction-jet turbine, according to the invention. The supply device 17 of the turbine is mounted on an end plate 24 of the casing 23, and the supply device 18 is mounted on an end plate 25. One of the bearings 7 of the turbine shaft 2 is mounted ona partition wall 26 dividing the interior of the casing 23 into two compartments: a compartment 27 and a compartment 28. The compartment 27 houses the jet pipes 10 and 11 having the thrust nozzles 12 and 13, respectively. The compartment 28 houses a reduction gear 29 having an output a-haft 30 and lay shafts 31 and 32. Bearings of the shafts 30, 31 and 32 of the reduction gear 29 which are,in the form of sealed bearings are mounted on the partition wall 26 and on the end plate 25 which is the end plate of the reduction gear 29 The same end plate 25 supports the second supply device 18 and the second bearing 7 of the shaft 2. The partition wall 26 sealingly separates the spaces 27 and 28 so that exhaust fluid cannot get into the reduction gear 29.

0 -, 1 The drive gear of the reduction gear 29 is the drive gear 8 of the shaft of the reaction-jet turbine. The gear 8 is positioned between the bearings 7 of the -shaft 2 and is in the compartment 28. An exhaust chamber 33 is mount- ed on the casing 23, an interior 34 of the exhaust chamber communicating with the compartment 27 through ports 35 of the partition wall 26.

The engine has a manually driven mechanical actuator in the form of an interlock device 36 having a handwheel 37 which couples the handwheel 37 to the output shaft 30 of the reduction gear 29 if necessary (for manual operation) and which automatically disengages them when pressure is supplied to the reaction-jet turbine.

The engine functions in the following manner.

When gas is supplied to the turbine through one of the supply devices 17 or 18. the turbine shaft 2 rotates in respective direction. Torque from the shaft 2 is transmitted through the drive gear 8 and reduction gear 29 to the output shaft 30 of the reduction gear and is then trans- mitted either to an actuator of the fitting or, via a crank mechanism with a "screw-and-nut" drive (not shown in the drawing). If there is no fluid pressure. the actuator of the fitting may be operated manually by means of the handwheel 37 which is positively coupled by means of the interlock device 36 to the output shaft 30 of the reduction gear 29. To ensure safety in case fluid is inadvertently supplied to the reaction- jet turbine. the device 36 automatically disengages the handwheel 37 from j. 1 - 17 the output shaft 30 upon pressure supply. During operation of the reaction-jet turbine, exhaust fluid ejected from the thrust nozzle 12 or 13 is admitted through the ports 35 of the partition wall 26 to the interior space 34 of the exhaust chamber 33 and is then either discharged outside or removed into a collecting manifold (not shown).

d 4- 4

Claims

CLAIMS:-

1 1. A reaction-jet turbine comprising a rotor in the form of a shaft having at least one axial passage-at least one jet pipe cantilevered to the shaft and having 5' at its distal end a thrust nozzle and commilnicatinR with an end inlet of the axial passage so as to form a continuous gas duct, and at least one gas dynamic supply device in the form of a supply pipe positioned coaxially with the shaft in a spaced relation to the end thereof, the outlet portion of the supply pipe being in the form of a supply nozzle whose minimum cross-sectional area is smaller than the minimum c--oss-secti onal area of the thrust nozzle, the ratio between these areas ensuring a shock wave in the entry zone of the axial passage of the shaft.

2. A reaction-jet turbine as claimed in claim 1, wherein the supply nozzle is in the form of a supersonic nozzle

3. A reaction-jet turbine as claimed in claim 1 or 2, 2 0 whe re in the spacing, between an end face of the_ supply nozzle and the end of the shaf t is in accordance with the formula:

< D D2 2tan t/2 whe re is the diameter of the axial passage of the shaft:

1 i 1 - 19 D2 is the internal diameter of the supply nozzle at its end face; and is the angle. of taper of the outlet portion of the supply nozzle.

4. A reaCtion-jet turbine substantially as described with reference to, and as shown in, the accompanying drawings.

Published 199 1 at The Patent Office. State House. 66171 High Holborn. Ln WC 1 R 4W. Further copies MY be Obta from Sales Bnawh. Unit 6 Nine Mile Point cwnlfchnfach. Cross Keys. Newport. NPI 7114 Printed by Multiplex techniques JUL St Cray. Kent-