Engine wash optimisation

Abstract

The present invention provides a method of optimising engine wash event scheduling. An underlying deterioration gradient and a total deterioration gradient are determined. A number of engine wash events, x, are set. Engine deterioration for x engine wash events is calculated. The washed engine cost of engine deterioration for x engine wash events is calculated. The calculation of engine deterioration is iterated for different x to optimise the number of engine wash events with respect to the cost of engine deterioration. Advantageously the method systematically optimises scheduling of wash events taking into account the underlying deterioration of the engine which cannot be recovered by engine washing and the cost of the engine wash events.

1 . A method of optimising engine wash event scheduling comprising:
 a) determining an underlying deterioration gradient;   b) determining a total deterioration gradient;   c) setting a number of engine wash events, x;   d) calculating engine deterioration for x engine wash events;   e) calculating the washed engine cost of engine deterioration for x engine wash events; and   f) iterating steps c) and d) for different x to optimise the number of engine wash events with respect to the cost of engine deterioration.   
     
     
         2 . A method as claimed in  claim 1  wherein step 1a) comprises steps of:
 a) in a fuel flow data series, identifying engine wash events; 
 b) for each data subset between consecutive engine wash events, identifying: a minimum point being a post-engine wash event fuel flow; a maximum point being a pre-engine wash event fuel flow; and a gradient-therebetween; and 
 c) calculating the underlying deterioration gradient by averaging the gradients between each adjacent pair of minimum points in the data series. 
 
     
     
         3 . A method as claimed in  claim 1  wherein step 1b) comprises steps of:
 a) in a fuel flow data series, identifying engine wash events; 
 b) for each data subset between consecutive engine wash events, identifying: a minimum point being a post-engine wash event fuel flow; a maximum point being a pre-engine wash event fuel flow; and a gradient therebetween; and 
 c) calculating a total deterioration gradient by averaging the gradients of all the data subsets. 
 
     
     
         4 . A method as claimed in  claim 2  wherein identifying engine wash events comprises identifying discontinuities in the data. 
     
     
         5 . A method as claimed in  claim 2  wherein identifying engine wash events comprises comparing the data to known engine wash event times. 
     
     
         6 . A method as claimed in  claim 1  wherein step 1d) comprises steps of:
 a) setting x engine wash events and sub-dividing the time by x to give x time segments; 
 b) for each time segment:
 i. calculating a segment underlying deterioration by integrating the underlying deterioration gradient by the time segment length; 
 ii. calculating a segment total deterioration by integrating the total deterioration gradient by the time segment length; 
 iii. subtracting the segment underlying deterioration from the segment total deterioration to give the segment deterioration; and 
 
 c) summing the segment deteriorations to give the engine deterioration. 
 
     
     
         7 . A method as claimed in  claim 6  wherein step 6a) comprises multiplying the segment time length by an utilisation factor. 
     
     
         8 . A method as claimed in  claim 1  wherein step 1e) comprises steps of:
 a) multiplying the engine deterioration by a pre-determined cost multiplier to give the cost of engine deterioration for x engine wash events; and 
 b) adding the cost of x engine washes to the cost of engine deterioration for x engine wash events to give a washed engine cost. 
 
     
     
         9 . A method as claimed in  claim 1  wherein a further step between steps 1e) and 1f) comprises:
 subtracting the washed engine deterioration cost from an engine deterioration cost where x=0 to give a washed cost saving. 
 
     
     
         10 . A method as claimed in  claim 9  wherein step 1f) comprises optimising the number of engine wash events with respect to the washed cost saving. 
     
     
         11 . A computer program having instructions adapted to carry out the method according to  claim 1 . 
     
     
         12 . A computer readable medium, having a computer program recorded thereon, wherein the computer program is adapted to make the computer execute the method according to  claim 1 . 
     
     
         13 . A computer program comprising the computer readable medium as claimed in  claim 1 .