Cooled component, casting core and method for the manufacture of the same

TECHNICAL FIELD

The present invention relates to the field of the art of gas turbines. It relates to a cooled component for gas turbines according to the preamble of Claim 1.

One such component is in the form of a turbine blade, for example from document GB-A-2202907 is known.

The invention further relates to a casting core for the manufacture of such a Component and a process for producing such a component.

STATE OF THE ART

The efficiency of gas turbines, which closely matches the height of the inlet temperature related to the hot combustion gases and for the sake of efficient Fuel economy and efficiency should be as high, is made material-technical reasons in particular extent dependent on efficient Use of the cooling air as a refrigerant usually the compressor stage is removed. The operational reliability and REMAIN except the gas turbine condition sufficient cooling of the thermally highly stressed turbine components and silo equipment, including in particular the inlet-side guide vanes and rotor blades of the first turbine stages include. Cooling can take be effected in different ways, eg by means of internal cooling (cooling the component by circulating cooling air in the inside) and / or by means of Film cooling (generating a cooling air film by suitably arranged outlet openings on the loaded outer side of the component).

A known method for efficient internal cooling is a "cyclone" (Or "vortex chamber" in GB-A-2202907). In such a "cyclone" is an elongated cooling channel with mostly circular or elliptical cross-section through a series of cooling air opens tangentially Anspeisebohrungen applied. The cooling air flowing forms a vortex in the cooling channel, the order the longitudinal axis of the channel and rotated and the high speed Turbulence in the edge region a particularly effective cooling of the duct wall and thus the cooled component causes.

In Fig. 1 is a simplified perspective view of a turbine blade 10 reproduced with such a known cyclone cooling. The turbine blade 10 is shown "transparent", so that the inner Cavities and channels can be identified as solid lines. The Turbine blade 10 has a leading edge ( "leading edge") 13 and a trailing edge ( "Trailing edge") 14, which between each longitudinally of the blade the blade root 11 and the blade tip 12 extend. The special Training of the blade root 11 for fixing the blade to the rotor and to Supplying the blade with cooling air, as described for example in US-A-4,293,275 or US-A-5,002,460 discloses 1 is in Fig. for the sake of Simplification is not reproduced.

For internal cooling of the turbine blade 10 is carried from the blade root 11 ago a not shown connecting channel cooling air into a longitudinally extending coolant channel 15 is fed (vertical arrows in Fig. 1). Parallel the coolant channel 15 and parallel to the to be cooled, particularly thermally loaded front edge 13 of the turbine blade 10 extends, a cylindrical cooling duct 16, which forms the cyclone. From coolant channel 15 is directed a number of transverse Anspeisebohrungen 17 to the cooling channel 16 and ends there in about tangentially. The tangentially through the Anspeisebohrungen 17 into the cooling channel 16 cooling air flowing (horizontal arrows in Fig. 1) forms an over the Channel extending pegs, the heat from the surrounding channel wall receives. The heated cooling air enters either end face from the cooling channel 16 from, or - as shown in the GB-A-2,202,907 - by tangential outlets in Form of bores or slots. Other facilities for internal cooling, the simultaneously serve for film cooling and / or with the trailing edge 14 in compound are, are omitted in FIG. 1 for simplicity.

The effect of the cyclone cooling depends mainly from the energiser (Boundary conditions, location and cross-sections of Anspeisebohrungen, etc.). Required are Anspeisebohrungen 17 with a bore diameter, the is smaller than half the hydraulic diameter of the cooling channel (cyclone) 16th Since a turbine blade 10 of the type shown in Fig. 1 by a conventionally Metal casting method is produced, must be for the training of the coolant passage 15, the cooling channel 16 and the two connecting Anspeisebohrungen 17 a corresponding multiply connected casting core are used. Weaknesses of such a casting core are due to the above-mentioned diameter condition comparatively thin connecting webs, which the cast when form later Anspeisebohrungen. At this point, it can therefore easily become a Nibs come who represents the success of the font in question.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a gas turbine component of the aforementioned structuring the nature so that the occurrence of core fractures during casting effectively restricted and the achieved during casting application rate significantly is improved.

The object is solved by the totality of the features of claim 1. The core of the invention, by a suitable design of the whole the Anspeisebohrungen the stiffness of the associated casting core to improve without compliance with the prescribed diameter conditions to give up the Anspeisebohrungen. This is done by the Anspeisebohrungen predominantly have a bore diameter, the is smaller than half the hydraulic diameter of the cooling channel, and that in order to Improving the application rate during the casting of the component selected Anspeisebohrungen have a bore diameter which is larger than the half the hydraulic diameter of the cooling channel.

According to a first preferred embodiment of the component according to the invention are selected Anspeisebohrungen respectively at the ends of the cooling channel arranged, in particular, the lowest and highest Anspeisebohrung are used as selected Anspeisebohrung. This may over the entire inner region of the cooling channel of the desired cooling air vortex practically unhindered form and its maximum cooling action unfold.

If the component, for example a turbine blade, particularly long, but it may in View of the stability of the core be advantageous if other according to a Embodiment, in addition in the middle region of the cooling channel selected Anspeisebohrungen are provided.

The inventive casting core for the production of such a component, which Casting core comprises a first duct part for forming the coolant passage, and a second duct part for forming the cooling channel comprises, as well as a plurality of Connecting webs which extend between the two channel members transversely and serve to form the Anspeisebohrungen, characterized in that the Connecting webs predominantly have an outside diameter smaller is than half the hydraulic diameter of the cooling channel, and that selected The connecting webs have an outside diameter which is greater than half the hydraulic diameter of the cooling channel.

Preferably, the selected connecting webs are each connected to the ends of the placed second channel part, in particular the bottom and the top Connecting web are used as selected connecting web.

The inventive method for manufacturing a component according to the invention by means of a metal casting process is characterized in that a according to the invention the casting core is used.

Further embodiments result from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

The invention is below with reference to exemplary embodiments in conjunction be explained in more detail with the drawings. Show it<dl tsize="6"><dt>Fig. 1</dt><dd>in a simplified perspective side view of a turbine blade presently known internal cooling of the leading edge by a so-called cyclone; </dd><dt>FIG. 2</dt><dd>perspective side view of a stiffened casting core for Producing a representation comparable to FIG. 1 Turbine blade according to a preferred embodiment of the invention; and</dd><dt>Fig. 3</dt><dd>in a comparable to FIG. 1 representation with the casting core produced from FIG. 2, the turbine blade.</dd></dl>

WAYS OF IMPLEMENTING THE INVENTION

In Fig. 3 as an exemplary embodiment of an internally cooled gas turbine component comparable to Fig. 1 turbine blade 10 'is played back according to the invention. Like parts of the turbine blade 10 'are the same reference numerals provided, as in the turbine blade 10 of FIG. 1. Also, in the turbine blade 10 'of the coolant channel 15 and the cooling channel 16 by a superposed series of Anspeisebohrungen 17 or 25, .., 27 connected. The majority of Anspeisebohrungen, namely the Anspeisebohrungen 17, meet the diameter produces the characteristic of a cyclone criterion namely that its bore diameter is smaller than half the hydraulic Diameter of the cooling channel 16. Few selected Anspeisebohrungen, namely the Anspeisebohrungen 25, 26 and 27 have a bore diameter , which is by way of derogation larger than half the hydraulic diameter of the cooling channel 16. By these selected Anspeisebohrungen 25, .., 27 may - as explained below - the application rate in the preparation of the blades can be significantly increased.

For the manufacture of the turbine blade 10 'by means of a metal casting process is a cast core 18 of the type shown in Fig. 2 required. The casting core 18 comprises a first channel part 19, the need for forming the coolant channel 15 is, and a second channel portion 20 for the formation of the cooling channel 16 responsible is. Both channel portions 19 and 20 are by a number of superimposed arranged connecting webs 21 and 22, .., 24 which in each case a having circular cross section. The plurality of connecting webs, namely "Thin" connecting webs 21, are used to form the Anspeisebohrungen that satisfy the above-mentioned "cyclone criterion" in terms of diameter. Only a few selected connecting webs, that the connecting webs 22, 23 and 24, are "thicker" formed and so reinforce the connection between the core parts 19 and 20 and thus the mechanical rigidity of the casting core 18 as a whole.

If the cooling channel 16 and the second channel part 20 is not very long, it is enough perfectly from which two outer connecting bars 22 and 24 as selected form connecting webs with enlarged cross-section. In this way may be virtually over the entire length of the cooling channel 16 of the cooling air vortex undisturbed form, because there the "cyclone criterion" is satisfied. For longer cooling channels 16 and channel members 20, it may be expedient and advantageous, individual selected connecting webs 26 provide in the central region, to the casting core 18 there to make stiffer.

The diameter of the selected Anspeisebohrungen 25, .., 27 or the selected Connecting webs 22, .., 24 is in each case greater than the chosen Half hydraulic diameter. be How big the diameter actually is, depends largely on the geometry of the casting core and the casting and has to be determined in each individual case.

LIST OF REFERENCE NUMBERS

<dl tsize="8" compact="compact"><dt>10,10 '</dt><dd>turbine blade</dd><dt>11</dt><dd>blade root</dd><dt>12</dt><dd>blade tip</dd><dt>13</dt><dd>leading edge</dd><dt>14</dt><dd>trailing edge</dd><dt>15</dt><dd>Coolant channel </dd><dt>16</dt><dd>Cooling channel (cyclone)</dd><dt>17</dt><dd>Anspeisebohrung</dd><dt>18</dt><dd>casting core</dd><dt>19,20</dt><dd>Channel part (casting core)</dd><dt>21</dt><dd>connecting web</dd><dt>22, .., 24</dt><dd>selected connecting web</dd><dt>25, .., 27</dt><dd>selected Anspeisebohrung</dd></dl>