Lock plate arrangement

Abstract

In gas turbine engines it is found that leaked coolant flow through the lock plates 28, 29, 50, 60 can be used to insulate the rotor surfaces 33, 34 from the effects of hot gas ingestion. In order to enhance this effect chutes 39, 59, 69 are provided to guide the leakage airflow adjacent to the lock plate such that the ingested hot gas flow is prevented from coming into contact with the surfaces of the lock plate and other cavity surfaces 33, 34 to improve cooling effect. The chutes 39, 59, 69 create apertures 40, 53 which can be of dimensions to ensure that there is a high ratio between width and depth of the coolant flow 32 again facilitating heat exchange and cooling efficiency.

1 . A lock plate for a blade mounting assembly within a gas turbine engine, the lock plate characterised by being integrally shaped to form a chute for direct outward marginal flow across the lock plate for presentation of a coolant flow substantially in alignment with the lock plate.  
   
   
       2 . A plate as claimed in  claim 1  wherein the chute is formed in an end of the lock plate.  
   
   
       3 . A plate as claimed in  claim 1  wherein the chute is formed intermediately between ends of the lock plate.  
   
   
       4 . A plate as claimed in  claim 1  wherein the chute is formed by a slot shaped within the width of the lock plate.  
   
   
       5 . A plate as claimed in  claim 1  wherein the chute extends substantially across the width of the lock plate.  
   
   
       6 . A plate as claimed in  claim 1  wherein the chute varies in dimensions dependent upon temperature.  
   
   
       7 . A plate as claimed in  claim 1  wherein the lock plate is formed by casting or moulding or machining.  
   
   
       8 . A plate as claimed in  claim 1  wherein the lock plate incorporates spacer protrusions upon at least one end in order to provide regulation of spacing between adjacent lock plates in use.  
   
   
       9 . A lock plate mounting arrangement for a gas turbine engine, the engine comprising a plurality of blades secured by lock plates in a mounting whereby there is a coolant leakage flow in use and an ingested hot gas flow about the blades by the operational function of the blades, the arrangement characterised by the lock plates associated with the mounting for the plurality of turbine blades, being as claimed in any preceding claim, and the chute being arranged to present the coolant flow adjacent the lock plates for insulating the rotor surfaces from the effects of hot gas ingestion.  
   
   
       10 . An arrangement as claimed in  claim 9  wherein the plurality of lock plates are provided in alignment about a mounting disc to form a circumferential barrier.  
   
   
       11 . An arrangement as claimed in  claim 9  wherein the chute is configured to minimise the effect of the ingressed hot gas flow by retaining the coolant flow adjacent to the rotor surfaces.  
   
   
       12 . An arrangement as claimed in  claim 9  wherein the chute extends over an edge of an adjacent lock plate.  
   
   
       13 . A gas turbine engine incorporating a lock plate as claimed in  claim 1.