EP0607357A1

EP0607357A1 - Method of driving a turbine in rotation by means of a jet device.

Info

Publication number: EP0607357A1
Application number: EP92922988A
Authority: EP
Inventors: Michele Martinez
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-10-11
Filing date: 1992-10-09
Publication date: 1994-07-27
Anticipated expiration: 2012-10-09
Also published as: ES2101877T3; FR2682428B1; AU2907492A; EP0607357B1; DE69218232D1; US5553995A; JP3320718B2; JPH06511528A; CA2121029A1; WO1993007361A1; FR2682428A1; ATE150133T1; CA2121029C; DE69218232T2; AU673658B2

Abstract

PCT No. PCT/FR92/00957 Sec. 371 Date Apr. 7, 1994 Sec. 102(e) Date Apr. 7, 1994 PCT Filed Oct. 9, 1992 PCT Pub. No. WO93/07361 PCT Pub. Date Apr. 15, 1993A turbine device and a method of driving the turbine device are disclosed. The turbine device includes an admission channel, a turbine, and an injection channel. The turbine device may also include a regulator. The turbine is driven by injecting a primary fluid into the admission channel at a given velocity and simultaneously causing a secondary fluid to flow into the admission channel at a lower velocity. The primary fluid and the secondary fluid form a mixture in the admission channel, which flows toward the turbine. The velocity of the mixture is less than that of the primary fluid, while the mass flow of the mixture is approximately equal to the sum of the mass flows of the primary and secondary fluids. The regulator compares the rotational speed of the turbine to a target speed and regulates parameters associated with the turbine device if the rotational speed of the turbine and the target speed differ by more than a predetermined amount.

Description

METHOD FOR DRIVING A TURBINE ROTATING BY AN EJECTOR DEVICE

The present invention relates to a method of driving a turbine in rotation and to a corresponding turbine device.

Turbines have been known for a long time and are essentially constituted by a hub carrying blades, driven in rotation by a fluid (gas, liquid) passing through it.

In known manner, driving a turbine with a fluid makes it possible to transfer the energy of the fluid to the axis of rotation of the turbine. For example, the rotation of this axis is used to drive an alternator to produce electric current, or to drive various tools (drilling, sawing, etc.).

To date, the problems of the known devices have resided in the high flow rates necessary for obtaining the highest possible powers. However, these high flow rates lead to strong disturbances; for example when the fluid is a gas, there is creation:

- shock waves,

- Expansion or compression beams 25 appearing on the various components of the device.

The consequences of such disturbances are inter alia that:

- the components of these devices must have particular, precise, optimum shapes (this

30 which implies a limited or even very limited area of use),

- said components must mechanically resist the forces induced by the phenomena

/ vibration accompanying these disturbances,

- said disturbances generate acoustic phenomena which are often very violent.

Another aspect limiting the use of prior turbine devices is the speeds high or even very high rotation of these devices.

The object of the present invention is to overcome all of these drawbacks and in particular to create a turbine whose nominal operating point is not associated with a transonic flow speed, in order to avoid all the problems linked to the disturbances induced by such flow.

It will be recalled that an operating point is characterized by a value torque (rotation speed, power) or (rotation speed, torque). In the present description, a nominal operating point is an operating point corresponding to a maximum power. The operating point corresponding to maximum torque will be called the operating point at nominal torque.

One of the aims of the invention is to obtain powers comparable to those obtained on conventional turbines, but with flow velocities compatible with flows that are undisturbed or little disturbed.

To this end, the present invention relates to a method for driving a turbine in rotation, said turbine being connected to an upstream fluid supply channel and to a downstream ejection channel, said method being characterized in that it consists of :

- injecting a primary fluid into the fluid supply channel, said primary fluid having a pressure Pp, a speed Vp and a determined mass flow rate dmp, - simultaneously admitting a secondary fluid into the fluid supply channel, this fluid having a pressure ps and a speed vs lower than those of the primary fluid, and a mass flow Dms,

- mix the primary and secondary fluids in the supply channel and direct the mixture of fluids to the turbine, this mixture having a mass flow rate equal to the sum of the mass flow rates of the primary and secondary fluids (dmp + Dms), driving the turbine in rotation by the passage of the fluid mixture over the blades of this turbine, and

- eject the fluid mixture by means of the fluid ejection channel.

Advantageously, the method according to the invention is a method of driving a turbine in rotation at a variable speed of rotation and further consists in: - continuously measuring a quantity representative of the actual speed of rotation of the turbine ,

- compare this actual rotation speed with the set rotation speed, - continuously modify one or more flow parameters so that the nominal operating point of the turbine corresponds to the set operating point.

Thus, the fact of injecting a primary fluid at higher pressure and speed than the secondary fluid drives the latter towards the turbine. This effect is known as the Venturi effect. However, this effect is used in the present invention as an energy transformer and speed reducer. Indeed, the Venturi effect, in this case, transforms the energy of the primary fluid injected by a nozzle with low mass flow and high speed and pressure, into the energy of a fluid (resulting from the mixing of said primary fluid with the secondary fluid sucked in by Venturi effect) characterized by a high mass flow and a low flow speed.

However, in known manner, the power available on the axis of rotation of the turbine is: P = C. ω. where C is the torque delivered and ω the speed of rotation of the turbine. The torque is expressed by: C = Fd where F is the overall radial force resulting from the flow of the fluid in the inter-blade channels of the turbine, and where d is the distance from the point of application of this force to the axis of the turbine.

In addition, if we take the case of a gas flow, as a first approximation, the force F is expressed by the following formula: F = Dmm (e sin (Be) - s sin (fis)) where :

- Dmm is the mass flow rate of the fluid passing through the turbine (that is to say of the fluid mixture),

- fie is the angle of attack of the turbine blades, - βs is the angle of the trailing edge of the turbine blades,

- We is the modulus of the relative speed (turning mark with the turbine) of fluid entering the turbine, - Ws is the modulus of the relative speed of fluid leaving the turbine.

For a given nominal operating point, therefore characterized by a given power and speed of rotation (/), a torque (C) and therefore a force (F) are sought. This force F is obtained by producing a high mass flow Dmm equal to the sum of the mass flows dmp + Dms, while having fluid flow speeds We and Ws sufficiently low to be compatible with a flow that is little disturbed. In addition, the method according to the invention makes it possible, by acting continuously on the pressure and / or the speed of the primary fluid and / or on any other dimensional or functional parameter of the turbine device, to be able to adapt the nominal operating point of the device at setpoint operating point.

The actual speed is measured continuously and then compared to a set speed. This setpoint speed is determined for a given application. For example, if the turbine drives a milling tool, this speed can be 36,000 rpm.

Following this comparison, one or more dimensional parameters are continuously modified or so that the measured speed is equal to the set speed.

Advantageously, to modify the dimensional parameters, the inlet sections of the secondary fluid, injection of the primary fluid and outlet of the fluid ejection channel, are continuously modified so as to equal, as much as possible, the set operating point and the nominal operating point. Advantageously, in order to modify the functional parameters, in addition to the pressure variation of the primary fluid, the injection of the primary fluid can be done according to a helical trajectory inducing self-limitation and self-adaptation of the operating regime of the turbine. Such an injection mode is said to be helical.

Likewise, advantageously, the injection of the primary fluid takes place in zones close to the walls of said supply channel. Such an injection mode is said to be parietal.

The present invention also relates to a turbine device implementing the method described above, said device comprising, inside a body having generally a symmetry of revolution, an upstream fluid supply channel, a turbine and a downstream fluid ejection channel, said device being characterized in that it further comprises:

means for injecting a primary fluid into the fluid supply channel, said primary fluid having a determined pressure, speed and mass flow rate,

means for admitting a secondary fluid into the fluid supply channel, this secondary fluid having a pressure and a speed lower than those of the primary fluid and a mass flow rate, means for mixing the primary and secondary fluids adapted to give the mixed fluids a mass flow rate equal to the sum of the mass flow rates primary and secondary fluids and to direct this mixture towards the turbine and thus drive this turbine in rotation.

Advantageously, the device is adapted to drive a turbine in rotation at a variable set speed and for this purpose comprises control and regulation means (50) comprising:

Means for measuring a quantity representative of the speed of rotation of the turbine, means for acquiring the measured speed of rotation,

- processing means adapted to compare the measured rotational speed, with a set rotational speed, - actuators adapted to regulate functional and / or dimensional parameters of the flow to make the measured value of the rotational speed coincide with the set value of this speed, and

- a stop valve. Thanks to such arrangements, a nominal operating point of the turbine is obtained, for a high torque, and a low speed of rotation compared with that obtained without the use of such arrangements on a comparable turbine. Advantageously, the device according to the invention is provided with actuators adapted to vary the intake section of the primary and secondary fluids, as well as the section of the ejection channel. It is thus possible to modify the nominal operating point of the turbine at will and to adapt it continuously to the set operating point.

Other objects, characteristics or advantages of the invention will emerge from the description which follows, by way of example, and with reference to the appended figures in which:

FIG. 1 is a schematic view illustrating the operating method of the device according to the invention, FIG. 2 is a view in longitudinal section of a turbine device according to the present invention,

FIGS. 3 and 4 are views respectively in longitudinal section and from above of a first alternative embodiment of a device according to the invention,

FIG. 5 is a view in longitudinal section of a second alternative embodiment of the device according to the invention,

FIG. 6 is a view in longitudinal section of a third alternative embodiment of the device according to the invention,

FIG. 7 is an enlargement of the detail referenced E in FIG. 6 and,

- Figure 8 is a schematic perspective view showing a blade mounted on a hub, and intended to form a turbine which can be used for the device according to the invention. As already indicated, the aim of the present invention is to drive a turbine in rotation, with a relatively low speed of rotation ω, of the order of 0 to 60,000 rpm, but with a high torque C. Thus, the product C. ω which gives the power P of the turbine remains high, without however the speed of rotation ω being.

To this end, the method for driving the turbine in rotation according to the invention is described below. The turbine being placed between an upstream fluid supply channel and a downstream ejection channel, the method according to the invention consists in:

- inject a primary fluid into the upstream fluid supply channel. This injection takes place at a pressure Pp, a speed Vp and a determined mass flow dmp,

- admit a secondary fluid into the upstream inlet channel. The pressure ps and the speed vs of this secondary fluid are lower than those of the primary fluid. The mass flow rate of this secondary fluid is dms,

- mix the primary and secondary fluids in the supply channel. The mixture thus obtained has a speed Vm and a pressure Pm higher than those of the secondary fluid, and lower than those of the primary fluid. The mass flow Dmm of this fluid mixture is equal to the sum of the mass flows dmp + Dms of the primary and secondary fluids, - direct the mixture of fluids towards the turbine,

- driving the turbine in rotation, by the passage of the fluid mixture, and

- eject the fluid mixture having passed through the turbine towards the outside.

Advantageously, this method makes it possible to drive a turbine in rotation according to a variable setpoint parameter and also consists in:

- continuously measure a parameter depending on the speed of rotation of the turbine,

- compare this measured rotation speed with a set speed. This measured speed of rotation is a function, among other things, of the dimensional and functional parameters of the flow, - continuously modify one or more parameters of the flow to adapt the nominal operating point of the turbine to the set operating point.

Advantageously, a modification is made to the dimensional parameters of the turbine device (variation of the inlet section of the secondary fluid, of the section of injection of the primary fluid and of the section of ejection of the ejection channel). As a result, the nominal operating point of the turbine is modified and the actual rotation speed is continuously regulated so that it corresponds to the set rotation speed.

The turbine device according to the invention is described below.

According to the embodiment shown in FIGS. 1 and 2, the device 10 according to the invention essentially comprises (FIG. 2): - an upstream fluid supply channel 11,

- a turbine 12,

a downstream fluid ejection channel 13,

injection means 14, and

- Control and regulation means 50 (Figure 1). These means 50 consist of:

- a stop valve 22,

- measuring means 19,

- acquisition means 20, and

- regulation means 52 comprising:. processing means 21, and

. actuators 51. The injection means 14 (FIG. 1) of primary fluid Fp in the supply channel 11 is placed at the upstream part 11a of the supply channel 11. This means 14 includes a nozzle 15.

A secondary fluid Fs is sucked into the upstream supply channel by the depression created by the injection of the primary fluid. Once in the upstream supply channel, these two fluids mix in the downstream part 11b of the supply channel 11. The length of this supply channel partly conditions the characteristics of the mixture of the fluids.

If necessary, a converging channel 16 is placed upstream of the turbine 12 and is intended to accelerate the mixing of fluids.

A deflector means 17, said upstream distributor, constituted by a fixed turbine wheel is placed upstream of the turbine 12, in order to direct the mixture of fluids optimally on the blades 18 of the turbine 12. The turbine 12 is thus driven in rotation.

The mixture of fluids is then ejected through the ejection channel 13 outside the turbine device. The purpose of such a channel is to adapt in particular the pressure of the fluid leaving the turbine to that of the fluid present around the ejection section.

The rotation of the turbine is used for any application, for example for driving tools, etc. as will be detailed with reference to FIG. 3.

The turbine device is also associated with control and regulation means 50. These means 50 comprise:

measurement means 19 of a quantity representative of the speed of rotation of the turbine 12.

These measurement means consist of two piezoelectric sensors (only one is shown in Figure 1) measuring the static pressures upstream and downstream of the turbine in undisturbed flow zones. The purpose of these two sensors is to multiply the measurement points, in order to compare their value and activate if necessary a stop valve 22 installed on the primary fluid supply pipe. These means must be reliable and give repetitive and significant measures,

Acquisition means 20, receiving and adapting the electrical quantities measured by the means 19,

- Processing means 21 adapted to define the instantaneous speed of rotation of the turbine (measured speed), and compare this measured speed of rotation to a set speed of rotation. If the measured and target speeds differ, the processing means sends a command order,

Actuators 51 constituted here by a pressure regulator receiving the command to control the treatment means and adapted to modify the injection pressure of the primary fluid and make the measured and set rotation speeds equal, and

- a safety shut-off valve 22 placed upstream of the primary fluid injection device in order to stop the operation of the device if necessary. This stop valve is also controlled by the processing means 21.

Thus, the device according to the invention is continuously regulated by the control and regulation assembly 50.

As a variant of this device, the converging channel 16 can be integrated into the upstream distributor 17.

As shown in Figures 3 and 4, the injection means 14 can take different forms.

In the example shown in Figures 3 and 4, the means corresponding to those described in Figure 2 are referenced as in Figure 2, but increased by a unit of one hundred. Figures 3 and 4 show a first variant of the device according to the invention.

The injection means 114 consist of two pipes 130 opening into the side wall of the upstream supply channel 111. Advantageously, these pipes are inclined at an angle α (FIG. 3) determined relative to the axis A of the device, and an angle β (FIG. 4) between the axis of the pipe 130 and a diametrical plane F passing through the axis of the turbine and the center of the injection section at the wall of the channel 111. Thus, the primary fluid Fp entrains the secondary fluid Fs in a helical path (helical injection) along the walls (parietal injection) of the upstream supply channel 111. This type of injection is called parieto-helical injection. This injection mode has the advantage of being self-adapting. In fact, when the speed of rotation of the turbine increases, the mass flow Dms of the secondary fluid also increases. The speed of the secondary fluid in the injection plane of the primary fluid in the supply channel has a module which increases and a direction which tends to approach the axis of the turbine. As a result, the flow of the mixture has a general incidence which decreases in the inlet plane of the turbine. Therefore, the available power tends to decrease if the increase in secondary mass flow is not taken into account and vice versa if the speed of rotation of the turbine decreases. This then results in a turbine device, whose free rotation regime (that is to say without resistive torque generated by the external medium on the axis of the turbine) is self-limited, and which has a strong peak of power for a low speed of rotation, characterizing the self-adaptation phenomenon of the flow.

By way of example, the speed of rotation corresponding to such a power peak is 12,000 rpm for a turbine with a diameter of 30 mm and a supply of primary fluid of the parieto helical type with three equally distributed inlet channels. along the circumference of the inlet channel (the angles α and β of inclination of the inlet pipes being 45 °).

It should be noted that the number of pipes 130 for injecting primary fluid may vary. For a better homogeneity of the primary fluid / secondary fluid mixture, it is advantageous to have a plurality of injection pipes distributed around the circumference of the supply channel.

Note that, in the embodiment presented in Figures 3 and 4, the ejection channel 113 has an axial direction. It will also be noted that with such an injection mode (helical parieto), it is not necessary to place a deflector device upstream of the turbine 112. According to an alternative embodiment (not shown) (the angle α fixing the initial slope of the injection propeller, the angle β defining the nominal diameter of the injection of this propeller), we continuously vary: - the angle α, which aims to vary the speed nominal nominal operating point and / or

- the angle β, which aims to modify the operating characteristics, primarily in secondary mass flow, therefore the maximum power at the nominal operating point.

It will be noted that the axis of rotation of the turbine can be directly constituted by a mandrel rod 160 of a tool 180.

The transmission of the engine force from a turbine to a tool poses technical implementation problems such as: - forces proportional to the inertia of the transmission members and to the square of the speed of rotation and

- The need to implement a transmission whose geometry can vary by the relative mobility of a number of constituent parts in order to be able to fix the tool on the transmission.

However, in the case of the tool-turbine assembly shown in FIG. 3 and, taking into account the moderate rotational speeds of the device, it is possible to use simple, rustic and inexpensive guide bearings in rotation and translation, commonly used in the industry to date.

In the example of such an embodiment, the turbine 112 is force-fitted onto the rear part 160 (mandrel rod) of the cylindrical tool 180, which can be a cutter.

The tool may have, for this purpose, at its mandrel rod, a set of small rectilinear edges oriented along the axis of rotation of said tool.

Alternatively, the tool can be associated with an intermediate fixing part (not shown).

In the example shown, the suspension bearing of the tool-turbine assembly is constituted by the bearings 183 and 184. The bearing 183 abuts on the hub of the turbine. A spacer 185, mounted just sliding on said tool, maintains the spacing with the bearing 184 so as to ensure the necessary functional clearance along the axis of rotation at the level of the bearing body 186.

A ring 187, made of a material whose coefficient of thermal expansion is lower than that of the material constituting said tool is mounted tight on said tool and comes to immobilize in translation (along the axis of rotation of the tool) the bearings 183 and 184 and 1 * spacer 185. The assembly thus produced consists of a small number of simple parts, inexpensive and of low inertia around the axis of rotation.

According to the embodiment shown in FIG. 5 (second variant), the mode of injection of the primary fluid is still different.

As before, the references of FIG. 2 have been used in this figure, increased by two units of hundreds.

The injection means 214 here consists of four conduits 230 (three are shown) opening out inside the supply channel 211, so that the primary fluid Fp is injected parallel to the axis A of the device and the along the walls. Such an injection mode is said to be parietal. As in the example in Figure 2, the primary fluid drives the secondary fluid to the turbine.

It will be noted that the number of pipes 230 for introducing the primary fluid may vary and that, preferably, the plurality of pipes is distributed along the circumference of the supply channel 211.

As a variant, each pipe 230 can pivot around its horizontal axis, to generate a flow that is no longer axial but helical. In this case, a helical-parietal flow is obtained with the advantages cited with reference to FIGS. 3 and 4, and associated with an upstream distributor 217.

Figures 6 and 7 show a third alternative embodiment of the turbine device according to the invention. As before, the references of FIG. 2 are repeated increased by three units of a hundred for the equivalent means represented in FIGS. 2 and 6.

The device 310 according to FIG. 6 has the particularity of having:

- an injection of primary air of the annular type and at the level of the walls (parieto-annular injection),

- actuators adapted to vary the inlet section of the secondary fluid, the injection section of the primary fluid and the ejection section of the ejection channel. In fact, the secondary fluid is introduced into the supply channel by an inlet device

350 having an opening 351 with variable section. The input device is screwed and unscrewed on the body of the supply channel 311 by means of a thread 352. This screwing (or unscrewing) is controlled by a means of modification of the input section, to namely the actuator 353. This actuator 353 is itself controlled by the processing means 321. As shown in arrow B, the action of this actuator 353 makes it possible to vary the inlet section of the secondary fluid.

Correspondingly, an actuator 354 for varying the ejection section of the device allows the screwing or unscrewing of an output device 356 via a thread 357. As shown by arrow C, the action of this actuator 354 makes it possible to vary the ejection section.

As before, the actuator 354 is controlled by the processing means 321. An actuator 355 making it possible to vary the injection section of the primary fluid in the supply channel 311 is also provided.

The primary fluid Fp is introduced into the supply channel 311 passing through a minimum section 358 called the neck section of the flow, this section varying through the actuator 355.

This neck is created (FIG. 7), on the one hand, by an annular bulge 359 of the wall of the supply channel 311 and, on the other hand, by a displaceable element 360 placed in the upstream part 311a of the channel. brought 311 and opposite the annular bulge 359.

By sliding along the arrow D of the element 360, the section of the neck 358 of primary fluid supply is variable. Sliding takes place by screwing and unscrewing the movable element 360 in the supply channel 311 by means of the thread 361.

It will be noted that the introduction of the primary fluid Fp into the supply channel 311 takes place parallel to the longitudinal axis A of the device. This injection is carried out around the entire circumference of the inlet channel and near the walls. This injection is called parieto-annular injection. As shown in FIG. 7, the respective shapes of the body 370 of the supply channel 311 and of the displaceable element 360 which faces it constitute an annular diverging convergent nozzle. Said annular diverging convergent nozzle, supplied with primary fluid by an annular section 371, therefore has a neck 358 and an outlet section 372 whose respective surfaces can vary when the actuator 355 drives the element 360 in translation. In the converging part from said nozzle, the primary fluid undergoes subsonic acceleration until reaching the sonic speed at said neck 358. In the divergent part of said nozzle, the primary fluid undergoes supersonic acceleration. In operation, the primary fluid supply pressure must be sufficient so that, taking into account the value of the surface of the injection section 372, the ejection of said primary fluid into the supply channel is supersonic and at a static pressure higher than that of said secondary fluid in section 373 of element 360. Indeed, it then creates on the outlet lips 374 of element 360 an expansion beam and a turbulent wake capable of promoting the exchange of energy between said primary and secondary fluids. In addition, the parietal injection following a convergent / diverging annular nozzle makes it possible, on the one hand, to increase the energy exchange surface between said primary and secondary fluids and, on the other hand, to obtain in the plane d input 375 (FIG. 6) of said distributor 317 has an optimum speed profile characterized in that the local average speed is all the more important as it is located near the head of the blades 318 of said distributor 317.

Such a dimensional and functional arrangement of a convergent / divergent nozzle at the level of the injection of the primary fluid can be generalized to all the injections of primary fluid, whatever the variant considered.

Such a device makes it possible, by acting on the dimensions of the primary and secondary fluid intake channels and on the dimension of the ejection channel, to vary the nominal operating point of the turbine.

Of course, all of the actuators 353, 354, 355 are controlled by the processing means 321. Another variant of the ejection device consists in producing a channel ejection channel leading the fluid from the outlet plane of the turbine. towards the level of the secondary fluid intake and thus allowing part of the ejected fluid to be recycled into the device.

The advantage of the device according to the invention, whatever the variant of embodiment chosen, resides in the fact that the torque delivered is significant for low rotational speeds and that the power delivered is comparable to that of existing turbines.

Now, blades will be described which can be used in each of the variants described above. However, to facilitate understanding of this description, we first recall the definitions of the main terms used:

- The leading edge of a blade is the portion of the curve located at the upstream end of said blade and which receives the flow.

- The trailing edge of a blade is the portion of the curve located at the downstream end of said blade and which sees the flow escape. - A blade consists of a so-called pressure surface and a so-called surface surface; these two surfaces intersect along the trailing edge and leading edge lines.

- A profile of a vane is the closed curve resulting from the intersection of the intrado and extrado surfaces with a cylindrical surface having as its axis that of the hub carrying the vane.

- The chord of a profile is the line segment joining on a blade profile the points of the trailing edge and the leading edge.

- A leading edge angle is the angle made by a straight line tangent to the profile at the point of the leading edge with the direction of the axis of said hub.

- A trailing edge angle is the angle made by a straight line tangent to the profile at the point of the trailing edge with the direction of the hub axis.

- The thickness of a profile at a given point on the lower surface is the length of the line segment delimited by said point on the lower surface and the point of the upper surface defined by the intersection of the upper surface with a straight line perpendicular to the lower surface at this point of the lower surface.

- The foot of a blade is the part of the blade adjoining the hub.

- The head of a blade is the part of the blade furthest from the hub.

The blades are described with reference to FIG. 2, but could just as easily be used with the variants shown in FIGS. 3 to 6. The turbine 12 (FIG. 8) is constituted by a cylindrical hub on which blades 18 which are circularly distributed are disposed radially. These blades are identical for the same turbine. The leading edge angles are constant along the leading edge for all the blades of the same turbine, the same for the trailing edge angles. The profile chord is constant for all the profiles of all the blades of the same turbine. The thickness of a profile is constant, except in the immediate vicinity of the trailing edge and the leading edge.

As a variant, the thickness of the profiles of a blade increases from head to foot of the blade in order to take into account the increasing mechanical stresses from head to foot of the blade.

It will thus be noted that the blades have a constant chord, a constant thickness along a cylindrical section having as axis that of said turbine, constant leading edge angles, constant trailing edge angles, curved surfaces of intrado and upper surface generated by a conical surface whose apex is the point of intersection of the axis of said turbine with the planes, perpendicular to the axis of said turbine, of inlet for the upstream part and outlet for the downstream part, and the apex angle of which is a function of the leading edge angle for the upstream part and the trailing edge angle for the downstream part.

Such blades are simple to produce (machining, molding, etc.) and inexpensive. In addition, such blades have the advantage, when the speed of the turbine increases, of also increasing the speed of the flow in the inter-blade channel. From a certain value of said flow speed, expansion and recompression significantly degrade the flow in the inter-vane channel. This results in a phenomenon of self-limitation of the free speed.

It will be noted that, thanks to the speeds of relatively low rotation (from 0 to 60,000 rpm), simple and common turbine suspension bearings can be used.

One of the advantages of the present invention is its lightness, its silent operation, its reliability. In addition, simple, inexpensive transmissions on the market can be easily adapted to such a turbine, for driving tools between 0 and 60,000 rpm. Of course, the present invention is not limited to the embodiments chosen and encompasses any variant within the reach of ordinary skill in the art. In particular, it is possible as a variant to produce at the level of the ejection planes of the device a pressure lower than the general level of pressure prevailing in the environment external to the device. The nominal power level of the device then does not vary significantly; on the other hand the mass flow injected decreases appreciably, this phenomenon characterizing the introduction of a second source of energy materialized by the depression at the outlet of the ejection channel, to the detriment of the source of energy defined by the primary fluid under pressure ; however, the precision of the control of the speed of rotation of the turbine by action on the pressure Pp of injection of the primary fluid decreases.

Claims

1 / - Method for driving a turbine in rotation (12, 112, 212, 312), said turbine being connected to an upstream supply channel (11, 111, 211, 311) of fluid and to a downstream channel (13, 113, 213, 313) of ejection, said method being characterized in that it consists in: injecting a primary fluid Fp, having a pressure Pp, a speed Vp and a determined mass flow dmp, into the channel d '' fluid intake, - simultaneously admitting a secondary fluid Fs into the fluid supply channel, this secondary fluid having a pressure ps and a speed vs lower than those of the primary fluid, and a mass flow rate Dms, - mixing the primary fluids Fp and secondary Fs in the supply channel (11, 111, 211, 311) and direct the fluid mixture to the turbine, this mixture having a mass flow rate equal to the sum (dmp + Dms) of the mass flow rates of the primary fluids and secondary, - drive the turbine in rotation by the passage of the fluid mixture over s blades (18, 118, 218, 318) of this turbine and

- eject the fluid mixture by means of the fluid ejection channel. 2 / - Method according to claim 1 for driving a turbine in rotation at a variable set speed, characterized in that it also consists in:

- continuously measure a quantity representative of the actual rotation speed ω of the turbine,

- compare this actual rotation speed with the set rotation speed,

- continuously modify one or more flow parameters so that the nominal operating point of the turbine corresponds to the set operating point.

3 / - Method according to claim 1 or 2, characterized in that it consists in determining the nominal operating point by:

- modifying an intake section (351) of the secondary fluid in the supply channel and / or by - modifying an injection section (358) of the primary fluid in the supply channel and / or

- modifying a section of the fluid ejection channel.

4 / - Method according to one of the preceding claims, characterized in that the primary fluid Fp is injected axially into the supply channel (11, 111, 211, 311).

5 / - Method according to one of claims 1 or 3, characterized in that the primary fluid Fp is injected parietally into the supply channel (11, 111, 211, 311).

6 / - Method according to one of claims 1 to 3, characterized in that the primary fluid Fp is injected so that the mixture of primary and secondary fluids is driven in a helical movement.

7 / - Method according to claim 6, characterized in that the helical movement is parietal.

8 / - Method according to one of claims 1 to 3, characterized in that the primary fluid is injected into the supply channel annularly.

9 / - Method according to one of the preceding claims, characterized in that it consists in carrying out a flow of liquid at a speed such that the flow is little or not disturbed. 10 / - Method according to one of the preceding claims, characterized in that a primary fluid Fp is used having a speed at an injection section (372) clearly supersonic before introduction into the supply channel (311 ). 11 / - Method according to claim 10, characterized in that it consists in mixing the primary and secondary fluids by means of expansion waves created by the primary supersonic fluid in the vicinity of its introduction into the inlet channel.

12 / - Method according to one of the preceding claims, characterized in that it further consists in calibrating angles α and β of the fluid mixture in an inlet plane of the turbine.

13 / - Method according to one of the preceding claims, characterized in that a quantity representative of the speed of rotation ω of the turbine is measured by measuring the static pressure upstream and downstream of the turbine (12, 112, 212 , 312).

14 / - Method according to one of the preceding claims, characterized in that it further comprises increasing the speed of the mixed fluids by passing it through a converging channel (16, 116, 216, 316) upstream of the turbine (12, 112, 212, 312).

15 / - Turbine device implementing the method according to one of claims 1 to 14, said device comprising, inside a body having generally a symmetry of revolution, an upstream channel (11, 111, 211, 311) for supplying fluid, a turbine (12, 112, 212, 312) and a downstream channel (13, 113, 213, 313) for ejecting fluid, said device being characterized in that it further comprises :

means for injecting (14, 114, 214, 314) a primary fluid Fp into the fluid supply channel, said primary fluid having a determined pressure, speed and mass flow rate dmp,

means for admitting a secondary fluid Fs into the fluid supply channel, this secondary fluid having a pressure and a speed lower than that of the primary fluid, and a mass flow rate Dms, and

- mixing means (11, 111, 211, 311) of the primary and secondary fluids adapted to give the mixed fluids a mass flow rate equal to the sum of the mass flow rates of the primary and secondary fluids and to direct this mixture towards the turbine and thus drive it in rotation.

16 / - Device according to claim 15, characterized in that it is adapted to drive the turbine at a variable set speed, said device further comprising control and regulation means (50) comprising: - measurement means (19) of a magnitude representative of the speed of rotation ω of the turbine,

- acquisition means (20) of the measured rotation speed,

processing means (21) adapted to compare the measured rotation speed with a set rotation speed,

actuators (51) adapted to regulate (21) functional and / or dimensional parameters of the flow in order to make the measured value of the rotation speed coincide with the set value of this speed, and

- a stop valve (22).

17 / - Device according to claim 15 or 16, characterized in that the injection means (14) is an injector having a nozzle.

18 / - Device according to claim 15 or 16, characterized in that the injection means (114,

214) comprises at least one pipe (130, 230) adapted to introduce the primary fluid along the wall of the supply channel.

19 / - Device according to claim 15 or 16, characterized in that the injection means (11) comprises at least one pipe (130) of inclination given α relative to an axis A of the supply channel and inclination β relative to an axis F of this supply channel, this pipe (130) being adapted to introduce the mixture of primary fluid Fp and secondary Fs into the supply channel according to a helical trajectory.

20 / - Device according to claim 15 or 16, characterized in that the injection means (314) is constituted by an annular space inside the supply channel, said annular space having a convergent section, a section of variable neck (358) and a divergent section.

21 / - Device according to one of claims 15 to 20, characterized in that the ejection channel (13, 113, 213, 313) is oriented radially and / or axially.

22 / - Device according to one of claims 15 to 21, characterized in that the measurement means consist of at least two sensors (19) adapted to measure the static pressures prevailing upstream and / or downstream of the turbine.

23 / - Device according to one of claims 15 to 22, characterized in that it further comprises:

- an actuator (355) adapted to vary the injection section of the primary fluid and / or

- an actuator (353) adapted to vary the intake section of the secondary fluid and / or

- An actuator (354) adapted to vary the ejection section of the fluid mixture. 24 / - Device according to claim 23, characterized in that each actuator (353, 354, 355) is controlled by the processing means (21).

25 / - Device according to one of the preceding claims, characterized in that the axis of rotation of the turbine consists of a mandrel rod (160) of a tool (180) driven by the turbine.

26 / - Device according to one of the preceding claims, characterized in that the turbine and / or an upstream distributor are provided with blades having a constant cord, a constant thickness along a cylindrical section having as axis that of said turbine, constant leading edge angles, constant trailing edge angles, curved lower and upper surfaces generated by a conical surface whose apex is the point of intersection of the axis of said turbine with the planes, perpendicular at the axis of said turbine, inlet for the upstream part and outlet for the downstream part, and the apex angle of which is a function of the leading edge angle for the upstream part and the trailing edge angle for the downstream part.