Patent Publication Number: US-8534122-B2

Title: Airflow testing method and system for multiple cavity blades and vanes

Description:
BACKGROUND 
     The present disclosure relates to a method and a system for performing airflow testing on multiple cavity turbine engine components such as blades and vanes. 
     The existing airflow testing method for multiple cavity blade and vanes requires independent flow testing of each cavity while blocking others. This is achieved by using multiple seals with part specific sealing configurations. Each seal allows air to flow to one passage. All other passages on the root bottom of the blade or vane being tested are blocked. Typically, the sealing is done at the root bottom surface interface of the blade or vane. Upstream of the bottom surface interface, air is supplied to a seal using one channel. For example, if one considers a blade with three passages, i.e. trailing edge (TE), middle cavity (MC), and leading edge (LE) passages, in order to complete the TE total flow test, a TE seal is needed to block the MC and LE passages and leave only the TE passage unobstructed. To complete all three flows using the existing airflow testing method, three independent set ups and three seals are needed. For every set up change, an operator must perform system diagnostics and actual parts testing. The diagnostic testing is time consuming and consists of a seal restriction test, a part leak test, and a master part test. As a result, for a blade with three cavities, three independent set ups need to be performed and a single batch of parts need to be tested three times for TE, MC, and LE passages. Thus, the existing system has long cycle times and allows parts processing in batches only. It is not possible to test a single piece flow. 
     In addition to total flow, a P-Tap testing of specific holes is required. The existing method uses manual P-Tap probes. This manual method has some deficiencies in accuracy, productivity, and ergonomic problems. 
     SUMMARY 
     Accordingly, it is desirable to have an airflow testing method and system which enables total flow testing of blades and vanes with multiple cavities using a single set up. 
     In accordance with the present disclosure, there is provided a system for airflow testing a turbine engine component having multiple cavities which broadly comprises a test fixture having means for supporting a turbine engine component to be tested and means for sequentially allowing a pressurized fluid to flow through each of the multiple cavities in the turbine engine component. 
     In accordance with the present disclosure, there is provided a method for airflow testing a turbine engine component having at least two cavities which broadly comprises the steps of providing a test fixture having a sliding element with one hole and a solid portion; positioning the turbine engine component within the test fixture; sequentially allowing a pressurized fluid to flow through each of the multiple cavities in the turbine engine component; and the sequentially allowing step comprising moving the sliding element so that the one hole is aligned with a first one of the cavities and the solid portion blocks at least a second one of the cavities. 
     Other details of the airflow testing method and system for multiple cavity blades and vanes are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a test fixture used in a method for airflow testing multiple cavity turbine engine components; 
         FIG. 2  is a sectional view of a portion of the test fixture of  FIG. 1 ; 
         FIG. 3  is an opposite side perspective view of the test fixture of  FIG. 1 ; and 
         FIG. 4  is a flow chart showing the steps of the airflow testing method. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, there is provided herein a method and a system for airflow testing a turbine engine component having at least two cavities, such as a blade or a vane used in a turbine engine. 
     The airflow testing system described herein enables total flow testing of turbine engine components with multiple cavities or passages using a single set up. This can be achieved by opening air flow to one of the cavities and blocking other cavities in the turbine engine component upstream of the turbine engine component&#39;s root bottom surface interface. In this system, the seal is provided with multiple openings and air is supplied to the seal using separate passages. Each of the passages is connected to the corresponding cavities on the turbine engine component&#39;s root bottom. Thus, when a three cavity component has a seal with trailing edge, middle cavity, and leading edge openings, each of the three openings is connected to separate passages. Thus, the trailing edge passage total flow is conducted by letting air through the trailing edge passage only and blocking the middle cavity and leading edge passages. The sequence of opening and closing the corresponding passages allows for components with multiple passages to be tested in one set-up without any process changeover. 
     The airflow testing system described herein also allows for automatic P-Tap testing using probes that are targeted to specific cooling film holes in an airfoil portion of the turbine engine component. The probes may be engaged automatically after the total flow is stabilized. 
     The entire sequence of individual cavities total flow and the corresponding P-Tap testing of the cooling film holes may be controlled by software and may be performed without operator interference. 
     Referring now to  FIG. 1  of the drawings, there is shown a test fixture  10  for holding a turbine engine component  12  having multiple cavities or passages, such as a blade or vane. The fixture  10  is provided with a first module  27  having a slot  14  for receiving a root portion  16  of the turbine engine component  12 . If desired, the slot  14  may have side walls  18  and  20  configured to mate with the shape of the sidewalls of the root portion  16 . 
     The turbine engine component  12  may have multiple cavities or passages as shown in  FIG. 2 . For example, the multiple cavities or passages may include a leading edge passage  22 , a middle cavity passage  24 , and a trailing edge passage  26 . The first module  27  has individual and separate passages  28 ,  30 , and  32  which align with the passages  22 ,  24 , and  26  respectively. An insert  34 , which acts a seal, may be positioned between the root portion  16  of the turbine engine component  10  and the first module  27 . The insert  34  may be formed from any suitable seal material such as a polymer material. The insert  34  has three individual and separate holes  36 ,  38 , and  40  which align with the aforementioned passages  22 ,  24 , and  26  and  28 ,  30 , and  32 . As shown in  FIG. 2 , the fixture  10  also has a second module  42  which communicates with a source  43  of a pressurized fluid, such as pressurized air, via conduit  44 . A sliding element  46  is positioned between the first module  27  and the second module  42 . The sliding element  46  is provided with a single hole  48  which can be aligned with one of the passages  28 ,  30 , and  32  and consequently with one of the passages  22 ,  24 , and  26 . The remainder of the sliding element  46  is solid for blocking the flow of the pressurized fluid to the others of the passages  28 ,  30 , and  32  and the passages  22 ,  24 , and  26 . 
     The sliding element  46  is reciprocably movable in a direction  50  parallel to a longer side of the root portion  16  of the turbine engine component  12 . By aligning the hole  48  in the sliding element  46  with one of the passageways  28 ,  30 , and  32 , pressurized fluid may be delivered to only one of the passageways  22 ,  24 , and  26  in the turbine engine component  12 . The solid portions of the sliding element  46  block the remaining passages  28 ,  30 , and  32  in the first module  27  and thus the remaining ones of the passages  22 ,  24 , and  26  in the turbine engine component  12 . After one has completed the testing of one of the passages  22 ,  24 , and  26 , the sliding element  46  may be moved so that the hole  48  is aligned with another one of the passages  28 ,  30 , and  32  so that a different one of the passages  22 ,  24 , and  26  can be tested. The sliding element  46  may be moved manually if desired, or automatically via an actuator  47  such as a linear motion actuator. By operating the sliding element  46  in this manner, the passages  22 ,  24 , and  26  may be sequentially tested in any desired order. 
     Software controls may be used to align the hole  48  with the passages  22 ,  24 , and  26  in the turbine engine component  12 . The software may also be used to select sonic nozzles to be used during the test and may also be used to engage the automatic P-Tap probes  72 ,  76 , and  78 . As will be discussed hereinafter, the P-tap probes  72 ,  76 , and  78  may be targeted to specific cooling film holes in an airfoil portion  58  of the turbine engine component  12 . The P-tap probes  72 ,  76  and  78  each have a flexible tip which comes into contact with a particular cooling film hole on the airfoil portion of the turbine engine component  12 . The opposite end of each P-tap probe  72 ,  76 , and  78  is connected to a processor (not shown) that detects the pressure sensed by the probes  72 ,  76  and  78  and outputs a result. 
     Referring now to  FIG. 1 , there is shown a holder  60  mounted to an upper surface  62  of the fixture  10 . The holder  60  has a base plate  64 , a support member  66  integrally formed with the base plate  64 , and an annular support  68  integrally formed with the support member  66 . The annular support  68  has an aperture  70  into which a targeted P-tap probe  72  may be inserted. The P-tap probe  72  may be secured to the holder  60  using any suitable means known in the art. The P-tap probe  72  is preferably targeted towards a cooling film home at the leading edge  74  of the turbine engine component  12 . 
     Referring now to  FIG. 3 , there is shown a holding system  80  for targeted P-tap probes  76  and  78 . The targeted P-tap probe  76  is targeted at a mid chord portion  77  of the turbine engine component  12 , while the targeted P-tap probe  78  is targeted at the trailing edge  79  of the turbine engine component  12 . 
     The holding system  80  includes a base plate  82  which is mounted to a surface  84  of the fixture  10 . The holding system  80  includes an upright web  86  which is integrally formed with the base plate  82 . The web  86  includes an arm  88  to which an annular holder  90  is integrally formed. The annular holder  90  is aligned at an angle with respect to the web  86  so that when the P-tap probe  76  is inserted in the aperture  92  and mounted to the holder  90 , it is pointed at the mid chord portion  77 . The web  86  further has an integrally formed angled portion  94  to which another annular holder  96  is joined. The annular holder  96  has an aperture  98  which is aligned so that when the P-tap probe  78  is inserted in the aperture  98  and is joined to the holder  96 , the probe  78  is pointed at the trailing edge  79  of the turbine engine component  12 . 
     Referring now to  FIG. 4 , the method for performing the airflow test of the turbine engine component  12  comprises in step  120 , providing the test fixture  10  having the sliding element  46  with the hole  48  and the solid portion. In step  122 , the turbine engine component  12  to be test is positioned within the test fixture  10 . Thereafter, in step  124 , the sliding element  46  is positioned so that the hole is aligned with one of the passages  22 ,  24 , and  26  of the turbine engine component  12 . Pressurized fluid is then allowed to flow into the open one of the passages  22 ,  24 , and  26 . In step  126 , when the flow is stabilized, one of the P-tap probes  72 ,  76  and  78  may be automatically moved into contact with a selected one of the cooling film holes. In step  128 , the pressure level of the selected cooling film hole is recorded when the pressure readings for the selected cooling film hole is stable. Thereafter, the sequence of steps  124 ,  126 , and  128  is repeated for each of the remaining passages  22 ,  24 , and  26  in the turbine engine component  12 . 
     There are a number of advantages to the airflow testing method and system. For example, the set up time is reduced by allowing multiple airflow passages on a blade to be tested with a single set up, rather than requiring many separate set ups. Further there is a cycle time reduction because the static probe testing under the method described herein is performed automatically by energizing P-tap probes to specific holes after the total pressure is stabilized, rather than performing the testing using manual probes. Still further, quality assurance may be improved by enabling the testing to be performed without operator interference. Yet further, the advantages include ergonomic advantages in that manual P-Tap probe testing and multiple tooling set ups are not needed. 
     There has been provided in accordance with the instant disclosure an airflow testing method and system for multiple cavity turbine engine components. While the airflow testing method and system have been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims.