Honeycomb Seals - Improve the efficiency of aero engines

How big is the fuel consumption of an airplane? For example, the Boeing 747 has a fuel consumption of about 12 liters per kilometer. From Hong Kong to London, it consumes a total of 116 000 liters (98 tons) of gasoline. The fuel consumption is amazing! In order to save high fuel costs, the engineering community invented the Honeycomb Seal Ring, a component that is widely used in the aviation industry to improve engine efficiency. Measuring this type of sealing ring with a honeycomb structure is a new challenge for the industry. Hong Kong-based HAESL - Hong Kong Aero Engine Repair Service Co., Ltd., located in the heart of the Asia Pacific region, successfully solved this problem; its new SRMS (Seal Ring Measurement System) optical honeycomb seal ring inspection system, through Renishaw's high performance The TONiCTM series of linear and circular encoders provide precise and reliable position feedback.

Mr. Liu Jianhua is a senior engineer who has been at HAESL for nearly 20 years; SRMS is a system jointly developed by HAESL and the Hong Kong Polytechnic University (PolyU), which revolutionized the way the industry measures honeycomb sealing rings. In the past, HAESL used vernier calipers for manual inspection. Manual inspection is not only time-consuming, but also relies on the technology and experience of the inspectors.

With the SRMS system, not only is the detection efficiency increased by 50%, but human error is reduced and the results are more consistent.

Honeycomb seal ring

Honeycomb seal ring

The honeycomb sealing ring is installed in the annular groove around the center of the shaft on the inner wall of the engine. It is mainly used to seal the radial gap between the rotating blades and the inner wall of the engine to reduce air leakage, thereby improving engine efficiency and reducing fuel consumption. When the aircraft is flying at high altitude, the engine material expands due to the temperature rise, and the honeycomb sealing ring just protects it: it provides a wearable layer to ensure that the blade does not rub against the inner wall of the engine. The size of the honeycomb group holes on the seal depends on the size of the rotating blades, ranging from 0.8 mm to 3 mm in diameter and 13 mm in depth.

HAESL engine repair shop

Reliable performance

Mr. Wu Yijun, the chief designer of the SRMS system, explained: “The integrated optical probe, roller screw, servo motor and turntable form a high-precision, reliable and maintenance-free inspection system. Unlike traditional probe systems, SRMS uses non- Contact optical inspection technology can effectively solve the most common problems encountered when measuring honeycomb sealing rings. The choice of Renishaw stems from our trust in its products. The successful cooperation projects in the past have made us deeply in the Renishaw grating. Understand that Renisau is guaranteed both in terms of product quality and performance. The Renishaw TONiC grating series has excellent anti-fouling capability, compact readhead design and easy installation, giving us full flexibility in system design. The two sets of TONiC gratings are mounted on the linear axis of the XY platform of the SRMS system. Thanks to the full support of Renishaw, the performance of the SRMS system is fully utilized."

SRMS Optical Honeycomb Seal Ring Detection System

Mr. Wu continued: “The positioning system of the turntable for the sealing ring has a decisive influence on the test results. We compared several different brands of gratings and found that the Renishaw grating has a high cost performance. In order to ensure that the turntable is in Runtime fluency and stability, the grating must provide low subdivision error, in this respect TONiC undoubtedly outstanding performance." Renishaw TONiC RESM circular grating system provides +/- 30 nm ultra-low subdivision error, resolution of 86.4 M CPR is sufficient for many high-end industrial applications. The low quality and low moment of inertia design of the circular grating enhances the system accuracy and dynamic performance, and the readhead uses a low noise (jitter) optical filtering system to further improve the stability of the position control.

Application of TONiC in optical honeycomb sealing ring detection system

Easy to install

All Renishaw's round encoders feature a patented tapered mounting that reduces installation errors and simplifies system integration. Mr. Wu said: “The taper mounting method is a major feature of Renishaw encoders, which greatly reduces the time and labor costs we use to correct shaft eccentricity.” In addition, each Renishaw reading head is equipped with LED mounting lights eliminate the need for an oscilloscope and other complex mounting aids, which greatly speeds up installation.

controlling software

Innovative design

SRMS is a high-precision optical inspection system that allows the operator to select the desired inspection items through the control panel, including the roundness, flatness, and PCD (Pitch Circle Diameter) hole diameter of the honeycomb seal ring (for installation). The system consists of three modules: the turntable, the main console and the integrated optical probe and software console.

Mr. Wu explained how SRMS works: “The integrated optical probe has a built-in high-precision 3R laser displacement sensor and an industrial camera that moves linearly on the XY stage of the main console. The laser displacement sensor measures the outer diameter of the seal ring and The inner diameter, the camera is used to capture the PCD hole image and remotely monitor the position of the LDS laser point. The optical technology makes the detection accuracy significantly improved, which is not provided by the traditional contact probe."

Optical honeycomb sealing ring detection system structure

During the test, the operator first places the honeycomb seal ring on the turntable. With an automatic calibration center function on the software, the placement error can be less than +/- 2 mm. Once you have selected the seal ring model from the database, you can begin the measurement. The probe stops at a pre-programmed position and collects displacement data between the honeycomb seal ring and the probe during rotation. The data of each point collected is sent to the software for analysis and calculation together with the corresponding angular position data provided by the Renishaw TONiC circular grating to obtain the test results.

Improve machine stability

In addition to Renishaw's gratings, HAESL also uses the Renishaw QC10 ballbar system to benchmark and track machine performance. The QC10 ballbar system quickly diagnoses problems with machine tools and sources of error that can cause these problems, allowing users to make preventive maintenance in advance, reducing the time wasted by failures and increasing the yield of the workpiece. Mr. Liu said: "We are currently actively considering upgrading the existing QC10 ballbar system to Renishaw's latest QC20-W series. The new system has more powerful features, such as Bluetooth wireless transmission technology, 'partial arc' Test and one-time setup for 3 flat tests."

The HAESL coordinate measuring machine also uses the Renishaw TP200 touch probe, which is equipped with a PH10 motorized head for part inspection. Mr. Liu said: “Detection is an indispensable procedure in the aviation industry. Renishaw is a global leader in the field of CMM probes and is undoubtedly our first choice.